Patent Publication Number: US-9893897-B2

Title: Encrypted data inspection in a network environment

Description:
RELATED APPLICATION 
     This Application is a continuation (and claims the benefit under 35 U.S.C. § 120) of U.S. application Ser. No. 13/656,406, filed Oct. 19, 2012, entitled “ENCRYPTED DATA INSPECTION IN A NETWORK ENVIRONMENT,” Inventors Xiaoning Li, et al. The disclosure of the prior application is considered part of (and is incorporated in its entirety by reference in) the disclosure of this application. 
    
    
     TECHNICAL FIELD 
     This disclosure relates in general to the field of network security and, more particularly, to inspecting encrypted data in a network environment. 
     BACKGROUND 
     The field of network security has become increasingly important in today&#39;s society. The Internet has enabled interconnection of different computer networks all over the world. However, the Internet has also presented many opportunities for malicious operators to exploit these networks. Certain types of malicious software (e.g., bots) can be configured to receive commands from a remote operator once the software has infected a host computer. The software can be instructed to perform any number of malicious actions, such as sending out spam or malicious emails from the host computer, stealing sensitive information from a business or individual associated with the host computer, propagating to other host computers, and/or assisting with distributed denial of service attacks. In addition, the malicious operator can sell or otherwise give access to other malicious operators, thereby escalating the exploitation of the host computers. Thus, the ability to effectively protect and maintain stable computers and systems continues to present significant challenges for component manufacturers, system designers, and network operators. 
     Enterprise environments deploy numerous network management tools, including firewalls, network intrusion detection/prevention (NIDS/NIPS) systems, traffic shapers, and other systems. A number of these systems rely on inspection of network traffic in order to provide a wide array of services, including the detection/prevention of malware propagation, ensuring corporate intellectual property is not leaked outside well defined enterprise boundaries, as well as general auditing and network management functions. Network traffic may also be encrypted using protocols such as Secure Sockets Layer (SSL)/Transport Layer Security (TLS). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To provide a more complete understanding of the present disclosure and features and advantages thereof, reference is made to the following description, taken in conjunction with the accompanying figures, wherein like reference numerals represent like parts, in which: 
         FIG. 1  is a simplified block diagram of a network environment in which a firewall may intercept a network flow in accordance with an embodiment; 
         FIG. 2  is an example illustration of a network environment  200  in accordance with an embodiment; 
         FIG. 3  is an illustration of a network environment with SSL/TLS handshake communications in accordance with an embodiment; 
         FIG. 4  is a block diagram of a network environment  400  for SSL/TLS in accordance with an advantageous embodiment; 
         FIG. 5  is an illustration of a security module as a proxy in accordance with an illustrative embodiment; 
         FIG. 6  is an illustration of a data diagram in accordance with an embodiment; 
         FIG. 7  is a simplified flowchart illustrating a process for extracting a shared secret using a shared library in accordance with an embodiment; 
         FIG. 8  is a simplified flowchart illustrating a process for extracting a shared secret from a memory space in accordance with an embodiment; 
         FIG. 9  is a simplified flowchart illustrating a process for analyzing an encrypted network flow in accordance with an embodiment; 
         FIG. 10  also illustrates a memory coupled to processor in accordance with an embodiment; and 
         FIG. 11  illustrates a computing system that is arranged in a point-to-point (PtP) configuration according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Example Embodiments 
     Turning to  FIG. 1 ,  FIG. 1  is a simplified block diagram of a network environment in which a firewall may intercept a network flow in accordance with an embodiment. In the embodiment illustrated in  FIG. 1 , network environment  100  can include Internet  102 , client  104 , a firewall  106 , a policy server  108 , a mail server  110 , and a web server  112 . In general, client  104  may be any type of termination node in a network connection, including but not limited to a desktop computer, a server, a laptop, a mobile device, a mobile telephone, or any other type of device that can receive or establish a connection with another node, such as mail server  110  or web server  112 . Firewall  106  may control communications between client  104  and other nodes attached to Internet  102  or another network, such as by blocking unauthorized access while permitting authorized communications. In some instances, firewall  106  may be coupled to or integrated with an intrusion prevention system, network access control device, web gateway, email gateway, mobile device, or any other type of gateway between Internet  102  and client  104 . Moreover, the location of firewall  106  in the routing topology close to user client  104  is arbitrary. 
     Policy server  108  may be coupled to or integrated with firewall  106 , and may be used to manage client  104  and to administer and distribute network policies. Thus, in this example embodiment, client  104  may communicate with servers attached to Internet  102 , such as mail server  110  or web server  112 , by establishing a connection through firewall  106  if permitted by policies implemented in firewall  106  and managed by policy server  108 . 
     Each of the elements of  FIG. 1  may couple to one another through simple interfaces or through any other suitable connection (wired or wireless), which provides a viable pathway for network communications. Additionally, any one or more of these elements may be combined or removed from the architecture based on particular configuration needs. Network environment  100  may include a configuration capable of transmission control protocol/Internet protocol (TCP/IP) communications for the transmission or reception of packets in a network. Network environment  100  may also operate in conjunction with a user datagram protocol/IP (UDP/IP) or any other suitable protocol where appropriate and based on particular needs. 
     For purposes of illustrating the techniques for providing network security in example embodiments, it is important to understand the activities occurring within a given network. The following foundational information may be viewed as a basis from which the present disclosure may be properly explained. Such information is offered earnestly for purposes of explanation only and, accordingly, should not be construed in any way to limit the broad scope of the present disclosure and its potential applications. 
     Typical network environments used in organizations and by individuals include the ability to communicate electronically with other networks using the Internet, for example, to access web pages hosted on servers connected to the Internet, to send or receive electronic mail (i.e., email) messages, or to exchange files. However, malicious users continue to develop new tactics for using the Internet to spread malware and to gain access to confidential information. Malware generally includes any software designed to access and/or control a computer without the informed consent of the computer owner, and is most commonly used as a label for any hostile, intrusive, or annoying software such as a computer virus, bot, spyware, adware, etc. Once compromised, malware may subvert a host and use it for malicious activity, such as spamming or information theft. Malware also typically includes one or more propagation vectors that enable it to spread within an organization&#39;s network or across other networks to other organizations or individuals. Common propagation vectors include exploiting known vulnerabilities on hosts within the local network and sending emails having a malicious program attached or providing malicious links within the emails. 
     For purposes of illustrating some example techniques of a security module and an extraction module, it is important to understand a man-in-the-middle (MITM) technique. One or more embodiments recognize and take into account that some embodiments for screening SSL (or TLS) traffic in security devices use MITM techniques: the security device terminates the SSL connection using a certificate that spoofs the destination, then proxies the data to the destination over a second SSL connection. The user can see this spoofing, and either ignores it explicitly for each connection, or sets his machine to trust the security device so the warning goes away. 
     MITM is expensive for the security device to implement, because it needs to decrypt and re-encrypt all traffic. Also, MITM requires the security device to perform expensive public-key cryptography operations on each connection being screened. 
     An additional problem with MITM is that the user does not get a true SSL authentication of the target web site (server). This is a key benefit of SSL security, but the user only knows that the security device is reached, and not the web site that has really been accessed. This deficiency can be exploited by attackers who using phishing emails to direct users to sites that look like trusted sites, but are really out to exploit them. 
     Additionally, the different embodiments of this disclosure recognize and take into account a situation where a trusted client is communicating with an untrusted server; the network device terminates and re-establishes an SSL/TLS session between two communicating endpoints. This is also often referred to as a break-make connection. The trusted client is provisioned with a certificate of the network device/domain and accepts this in the secure session setup process, even though it is communicating with an endpoint beyond the network appliance (e.g. a banking website). In practice, this session is terminated at the network appliance, which instantiates a second, separate session to the ultimate endpoint, on behalf of the client. This mechanism allows the network appliance to get visibility to the TLS traffic, as it is a ‘man-in-the-middle’ for the secure communication channel. This approach results in a burden on the network appliance, as it needs to proxy connections for every client/session, hence needs to manage resources for all of these proxy connections. This situation adds significant overhead to the network appliance. 
     Also, the different embodiments of this disclosure recognize and take into account another situation where an untrusted client is communicating with a trusted server, the network appliance gets access (in some OOB manner) to the trusted server&#39;s certificate, including the public/private key pair (e.g. RSA keys) used for authenticating the SSL/TLS session. Because of the SSL/TLS operation, where the client sends a pre-master secret to the server, encrypted with the public key of the server, the network appliance is able to capture/decrypt this information en route and snoop on the SSL/TLS handshake. This allows the network appliance to independently compute the SSL/TLS session keys and thereafter decrypt the encrypted communication between the two endpoints. However, this situation relies upon ownership of the server private key, and does not apply in the common situation of an organization that seeks to protect multiple users with client machines that are connecting to multiple servers on the Internet, by provisioning a security device, such as Intrusion Protection or Firewall. 
     The different embodiments of this disclosure recognize and take into account: enterprises have pressing need to scan SSL/TLS traffic; malware inspection; data loss protection; MITM techniques already in use; MITM fakes both authentication and encryption; user sees forged certificate, trust is compromised; annoyance factor when a user either sees a warning message for every connection, or never knows whether trust is real. 
     One or more embodiments of this disclosure provide a novel approach which simplifies visibility into encrypted network streams, as well as alleviating large overheads on the network devices. 
       FIG. 2  is an example illustration of a network environment  200  in accordance with an embodiment. In an aspect of this disclosure, network environment  200  is includes a client  202 , a firewall  204 , and a server  206 . Network environment  200  may be one example of network environment  100  as shown in  FIG. 1 . In an embodiment, network environment  200  may include an encryption protocol session  208  that operates between client  202 , firewall  204 , and server  206 . Encryption protocol session  208  may further include network flow  210 , targeted data  211 , and shared secret  212 . Server  206  may further include certificate of authority  214 . Firewall  204  may further include security module  220 , which in turn may include a network flow copy  222  and an unencrypted network flow  224 . Client  202  may further include trust list  216 , extraction module  230 , shared library  232 , and application  234 . 
     In an embodiment of this disclosure, server  206  includes certificate of authority  214 . Certificate of authority  214  may be an entity that issues digital certificates. The digital certificate certifies the ownership of a public key by the named subject of the certificate. This allows client  202  to rely upon signatures or assertions made by the private key that corresponds to the public key that is certified. In this model of trust relationships, certificate of authority  214  is a trusted third party that is trusted by both server  206  and client  202  upon the certificate. On client  202 , trust list  216  may be maintained. Trust list  216  may include the digital certificates that client  202  trusts. 
     In one or more embodiments, encryption protocol session  208  operates between client  202 , firewall  204 , and server  206 . Encryption protocol session  208  includes a network flow  210 . Network flow  210  is an encrypted flow of data that operates in both directions between client  202  and server  206 . Firewall  204  may intercept network flow  210  for inspection and analysis. In an embodiment, the protocols used for encryption protocol session  208  (secure communications) may be transport layer security (TLS) or its predecessor, secure sockets layer (SSL). These protocols are cryptographic protocols that provide communication security over the Internet. These protocols may also be used interchangeably in this disclosure. TLS and SSL encrypt the segments of network connections at the application layer for the transport layer, using asymmetric cryptography for key exchange, symmetric cryptography for confidentiality, and message authentication codes for message integrity. 
     Client  202  and server  206  may also maintain a shared secret  212  (e.g., a password, key, etc.) for authentication of data in network flow  210 . Shared secret  212  may be configured during encryption protocol session  208 . Shared secret  212  may be a value that is shared, and known, between client  202  and server  206 . In an embodiment, for example, shared secret  212  may be a master secret or session keys as used in SSL/TLS. Session keys may be a session context and may include an initialization vector, crypto algorithm being used, etc., as well as just the session key. A session context may contain necessary cryptographic information to de-capsulate the payload (e.g. encryption/integrity/compression algorithms, associated keys, key sizes, Initialization vectors, etc.) In contrast, a public/private asymmetric key structure is not shared between client  202  and server  206  because each party has different keys. 
     Extraction module  230  is configured to extract shared secret  212  from client  202 . In particular, extraction module  230  may extract the master secret, pre-master secret, hash-based message authentication code (HMAC), and/or session keys. Extraction module  230  may be loaded onto client  202 , or in other embodiments, may be a separate module with access to client  202 . 
     In an embodiment, extraction module  230  may load shared library  232  into application  234 . This allows extraction module  230  access to encryption protocol session  208  through application  234  to identify shared secret  212 . Shared library  232  may be a shared library or shared object is a file that is intended to be shared by executable files and further shared objects files. Shared library  232  may be, for example, a dynamic link library (DLL). Application  234  may be a process that is communicating with server  206  through encryption protocol session  208 . Application  234  may be, for example, a web browser. 
     In another embodiment, extraction module  230  may be configured to monitor network flow  210  at a network layer and detect the progress of a network handshake, such as the SSL initial handshake, and so determine the point in time when memory space  231  of application  234  may contain the shared secret  212  for the encrypted connection being negotiated. Extraction module  230  may be configured to open the memory space  231  of the process running the application  234 , for example, by using debugging system calls to access the process memory of a target process on the same computer system in Microsoft®, Windows®, or Linux®. Extraction module  230  may also be configured to search memory space  231  to identify shared secret  212 . 
     Extraction module  230  is configured to send shared secret  212  to security module  220 . The path of transmission to security module  220  may also be a secured channel. 
     With shared secret  212 , security module  220  may be able to decrypt network flow  210  using the same encryption/decryption process as client  202  and server  206  are using. Security module  220  may operate in different modes of operation. 
     In one embodiment, security module  220  may be configured to copy network flow  210  to create network flow copy  222 . Network flow copy  222  may then be decrypted without affected network flow  210  to create unencrypted network flow  224 . In some embodiments, security module  220  may delay network flow  210  to wait for shared secret  212  from encryption module  230 , have time to decrypt network flow copy  222 , modify network flow  210 , inspect unencrypted network flow  224  for security issues, or any other suitable reason for delaying. In other embodiments, security module  220  does not delay network flow  210  and may only copy network flow  210 . 
     In an embodiment, security module  220  may be configured to scan network flow  210  and/or network flow copy  222  (once decrypted and as unencrypted network flow  224 ) for targeted data  211 . Targeted data  211  may contain data that security module  220  is looking for such as, for example, hostile, intrusive, or annoying software such as a computer virus, bot, spyware, adware. Targeted data  211  may be malware. 
     In operational terminology, and in one particular embodiment, an illustration of a TLS or SSL connection may begin as follows: during a negotiation phase client  202  sends a message specifying the highest TLS protocol version it supports, a random number, a list of suggested cipher suites, and suggested compression methods. A cipher suite is a named combination of authentication, encryption, and message authentication code (MAC) algorithms used to negotiate the security settings for a network connection using the TLS or SSL network protocols. Also, if client  202  is attempting to perform a resumed handshake, it may send a session ID. 
     In response, server  206  responds with a message containing the chosen protocol version, another random number, a selected cipher suite, and a selected compression method from the choices offered by the client. To confirm or allow resumed session, server  206  may send the same session ID. To start a new session, server  206  may send a new session ID. Also, client  202  may respond with another message, which may contain a pre master secret, public key, or nothing. The pre master secret is encrypted using the public key of the server certificate. Client  202  and server  206  then use the random numbers and the pre master secret to compute a common secret, called the “master secret”. All other key data for this connection is derived from this master secret. The master secret may be used to make session keys for each communication session between client  202  and server  206 . The pre master secret, master secret, and session keys are all examples of shared secret  212 . 
     One or more embodiments provide extraction module  230 , also referred to as a trusted agent, on client  202  that monitors SSL/TLS connections and is able to intercept certain, well defined, application programming interfaces (APIs) to directly extract the master secret, pre-master secret, and/or the session key. Extraction module  230  on client  202  may perform the extraction of shared secret  212 . This information is securely shared to security module  220 , a trusted and authorized network appliance, via a secure out-of-band (OOB) channel. In other embodiments, the information is shared via a non-secure channel. This allows security module  220  to decrypt encryption protocol session  208 , SSL/TLS communication, and get visibility into network flow  210 . 
     In operational terminology, and in particular, one embodiment, extraction module  208 , special software, on client  202 , the user workstation, searches out shared secret  212 , the SSL key, as each encryption protocol session  208  is established. Discovery protocols then transmit shared secret  212  securely to security module  220 . Client  202  establishes the SSL connection end-to-end, with full authentication of the target site, but security module  220  can still scan the connection to protect client  202 . 
     In addition, shared secret  212  may shared with security module  230  only after a public-key handshake occurs, so security module  230  can decrypt the session using a single symmetric decryption per data item. This process is faster than MITM. 
     One or more embodiments of this disclosure (1) preserves end-to-end authentication and that it can be used for passive connections to the network, (2) alleviate overhead on a security module to store state for every single connection, where a second, independent SSL/TLS connection must be constructed in order to get visibility into the encrypted traffic streams, and (3) are compatible with the user of client-side certificates in SSL (not supported in MITM). 
     The embodiments of this disclosure provide a client based approach to extract the SSL/TLS master secret and/or session keys and sharing these with authorized security modules using a separate secure channel. The embodiments also enable scanning of the network flow without removing the ability of the client to perform end-to-end authentication and in a way that is very efficient for the security devices (IPS, Firewall, security module) to implement. 
     The embodiments of this disclosure provide a system to decrypt encryption protocol sessions (SSL/TLS sessions) without compromising client trust. The embodiments provide: SSL Handshake is passed on without change; original certificate, original CA trust; extraction module shares session key with security module; key is a short-lived credential, affects only this session; decryption can also be faster than MITM; decryption can also support SSL mutual authentication client-side and server authentication; and can support passive mode inspection of traffic. 
     The embodiments also provide: the security device can also be used in a proxy environment, where proxy may need to modify the SSL plaintext; authentication and trust are still end-to-end; connection starts in “inspection mode”, where all data is pass-through; If proxy needs to change plaintext (e.g., modifying a URL, removing an attachment), connection switches to “proxy mode”. In one or more of the embodiments, a crypto state is divided between host and server. The client decrypt state is copied to become the initial server encrypt state. The server decrypt state is copied to become the initial client encrypt state. The security device both decrypts and re-encrypts SSL data, using the separate states. SSL plaintext can be modified in between these steps. The crypto states within the proxy diverge between received state and re-encrypt state once the proxy modifies plaintext. Once re-encryption starts, it continues until the connection terminates. 
     The security module may use SSL key information to decrypt/verify SSL session information and inspect SSL packets in further for malware detection or data loss protection. 
     One or more embodiments of this disclosure provide for modifying the SSL/TLS handshake in order to change the SSL parameters that can be negotiated. In such embodiments, the Initialization Vector (IV) must also be derived to allow the modification of the SSL/TLS FINISH handshake message. This may be accomplished by using the master secret as the shared secret. In another embodiment, the IV may directly be extracted by the extraction module and shared with the security module, in the same manner as sharing the SSL/TLS session key. 
     In an embodiment, a handshake may be rewritten as follows:
         For the ServerHello/ClientHello by:
           A) Limiting the list of the cipher suites in the Hello to an approved list;   B) Changing the list of cipher suites in the ClientHello to an approved list;   C) Changing the selected cipher suite in the ServerHello to one in an approved list;   D) Changing the random data from a client/server to a more secure source; and   E) Not allowing session resumption by removing the session from the Client Hello.   
           For the ClientCertificate by:
           A) Supplying one or more Client Certificates;   B) Replacing one or more Client Certificates; and   C) Removing one or more Client Certificates.   
           For the ClientKeyExchange by changing the random data from a client/server to a more secure source.       

     In one example implementation, client  202  and/or firewall  204  are network elements, which are meant to encompass network appliances, servers, routers, switches, gateways, bridges, load balancers, processors, modules, or any other suitable device, component, element, or object operable to exchange information in a network environment. Network elements may include any suitable hardware, software, components, modules, or objects that facilitate the operations thereof, as well as suitable interfaces for receiving, transmitting, and/or otherwise communicating data or information in a network environment. This may be inclusive of appropriate algorithms and communication protocols that allow for the effective exchange of data or information. However, user client  202  may be distinguished from other network elements, as they tend to serve as a terminal point for a network connection, in contrast to a gateway or router that tends to serve as an intermediate point in a network connection. Client  202  may also be representative of wireless network nodes, such as a smartphone, or other similar telecommunications devices. 
     In regards to the internal structure associated with network environment  200 , each of client  202  and/or firewall  204  can include memory elements for storing information to be used in the operations outlined herein. Each of client  202  and/or firewall  204  may keep information in any suitable memory element (e.g., random access memory (RAM), read-only memory (ROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), application specific integrated circuit (ASIC), etc.), software, hardware, or in any other suitable component, device, element, or object where appropriate and based on particular needs. Any of the memory items discussed herein (e.g., memory elements  250  and  252 ) should be construed as being encompassed within the broad term ‘memory element.’ The information being used, tracked, sent, or received by client  202  and/or firewall  204  could be provided in any database, register, queue, table, cache, control list, or other storage structure, all of which can be referenced at any suitable timeframe. Any such storage options may be included within the broad term ‘memory element’ as used herein. 
     In certain example implementations, the functions outlined herein may be implemented by logic encoded in one or more tangible media (e.g., embedded logic provided in an ASIC, digital signal processor (DSP) instructions, software (potentially inclusive of object code and source code) to be executed by a processor, or other similar machine, etc.), which may be inclusive of non-transitory media. In some of these instances, memory elements can store data used for the operations described herein. This includes the memory elements being able to store software, logic, code, or processor instructions that are executed to carry out the activities described herein. 
     In one example implementation, client  202  and/or firewall  204  may include software modules (e.g., extraction module  230  and/or security module  220 ) to achieve, or to foster, operations as outlined herein. In other embodiments, such operations may be carried out by hardware, implemented externally to these elements, or included in some other network device to achieve the intended functionality. Alternatively, these elements may include software (or reciprocating software) that can coordinate in order to achieve the operations, as outlined herein. In still other embodiments, one or all of these devices may include any suitable algorithms, hardware, software, components, modules, interfaces, or objects that facilitate the operations thereof. 
     Additionally, each of use client  202  and/or firewall  204  may include a processor  260  and  262  that can execute software or an algorithm to perform activities as discussed herein. A processor can execute any type of instructions associated with the data to achieve the operations detailed herein. In one example, the processors could transform an element or an article (e.g., data) from one state or thing to another state or thing. In another example, the activities outlined herein may be implemented with fixed logic or programmable logic (e.g., software/computer instructions executed by a processor) and the elements identified herein could be some type of a programmable processor, programmable digital logic (e.g., a field programmable gate array (FPGA), an EPROM, an EEPROM) or an ASIC that includes digital logic, software, code, electronic instructions, or any suitable combination thereof. Any of the potential processing elements, modules, and machines described herein should be construed as being encompassed within the broad term ‘processor.’ 
       FIG. 3  is an illustration of a network environment with SSL/TLS handshake communications in accordance with an embodiment. Network environment  300  includes client  302 , firewall  304 , and server  306 . Furthermore, client  202  includes extraction module  308 , firewall  304  includes security module  310  to perform security inspection  316 , and server  306  includes server certificate  312 . 
     Server certificate  312  may be on example of certificate of authority  214  in  FIG. 2 . Server certificate  312  may be passed through to client  202 . Client  202  may store server certificate  312  in real certificate authority trust  314 . Real certificate authority trust  314  may be one example of trust list  216  in  FIG. 2 . 
     Network environment  300  also includes messages  320 - 336 . Messages  320 - 336  may be messages included as part of a handshake for an SSL/TLS session. An SSL/TLS session may be one example of encryption protocol session  208  in  FIG. 2 . 
     Messages  320  and  322  may be initial messages that include a ClientHello and a ServerHello. Firewall  304  may allow message  320  to pass through. Even though message  320  and  322  are labeled separately, they contain the same information. 
     Messages  324  and  326  may be server  306  sending client  302 , server certificate  312 . Firewall  304  also passes through these messages. Even though message  324  and  326  are labeled separately, they contain the same information. By passing through server certificate  312 , client  302  can confirm that communications are coming from server  306 . 
     Messages  328  and  330  are the finishing messages for negotiation. Even though message  324  and  326  are labeled separately, they contain the same information. In other embodiments, if security module  310  wants to select the cipher suite, security module  310  may alter messages  328  and/or  330 . In this case, they may not be the same. 
     Message  332  may be when extraction module  308  sends a shared secret to security module  310 . Message  332  may also be a secure message. 
     Messages  334  and  336  may represent the network flow. These messages show the data that is passed through firewall  306 . In one or more embodiments, firewall  306  allow these message to pass through, in other embodiments firewall  306  may go between messages  334  and  336 . In the later situation, firewall  306  may delay, terminate, or modify messages  334  and  336 . 
       FIG. 4  is a block diagram of a network environment  400  for SSL/TLS in accordance with an advantageous embodiment. Network environment  400  includes client  402 , firewall  404 , and server  406 . Furthermore, client  202  includes extraction module  408  and firewall  304  includes security module  310 . Client  402  may be one example of client  202  as shown in  FIG. 2 . Firewall  404  may be one example of firewall  204  as shown in  FIG. 2 . Server  406  may be one example of server  206  as shown in  FIG. 2 . 
     Client  202  further includes application  412  and operating system (OS)  414 . Application  412  may be a process that initiates an encryption protocol session with server  406 . Application  412  may be loaded into operating system  414  that handles the actual transmission of data to server  406 . 
     Extraction module  408  may extract a shared secret from operating system  414  and/or application  412 . Extraction module performs key sharing to send the shared secret (SSL session key or master secret) to security module  410 . This allows security module to perform decryption  416  on the network flow between operating system  414  and server  406 . The network flow may be SSL/TLS encrypted traffic. 
       FIG. 5  is an illustration of a security module as a proxy in accordance with an illustrative embodiment. A network environment  502  may include a network flow  504 , a security module  506 , a client decrypt state  508 , a server decrypt state  510 , a client encrypt state  512 , and a server encrypt state  514 . 
     Security module  506  in part (a) of  FIG. 5  may be a proxy in inspection mode. When in inspection mode security module  506  is copying and decrypting network flow  504 . Security module  506  uses client decrypt state  508  to decrypt network flow  504  coming from a client and server decrypt state  510  to decrypt network flow  504  coming from a server. 
     In part (b) of  FIG. 5 , security module  502  is transitioning into proxy mode. Security module  506  may take client decrypt state  508  to create server encrypt state  514  and take server decrypt state  510  to create client encrypt state  512 . In addition to decrypting like in part (a) in inspection mode, security module  506  can also encrypt in proxy mode in part (c). 
     In part (c), security module  506  is in between network flow  504 . During proxy mode, security module  506  may pass through, decrypt/encrypt, terminate, and/or modify network flow  504 . To modify network flow  504 , security module may decrypt as before in part (a), but then use client encrypt state  512  and/or server encrypt state  514  to also encrypt network flow  504 . In an embodiment, once security module begins modifying network flow  504 , security module  506  may encrypt/decrypt the rest of network flow  504  for the rest of the encryption protocol (SSL/TLS) session. 
       FIG. 6  is an illustration of a data diagram in accordance with an embodiment. Data diagram  600  shows a typical SSL/TLS data structures. Data diagram  600  includes data structures  602 - 616 . 
     The extraction module may inspect a target application memory and address related data structures  602 - 616  with API hooks or signature based scanning. The client may be protected by other security services to protect sensitive SSL key information before it is sent to a security module via a secure OOB channel. 
     In an embodiment, a decrypt path might be Wininet.dll including CFSM:RunworkItem, CFSM:Run, CFSM:SecureReceive, ICSECURESOCKET::RECEIVE_FSM, ICSecuresocket::DecryptData, and ICSecuresocket::DecryptData. Then, Sspiceli.dll, which includes DecryptMessage and LsaunsealMessage. Then Schannel.dll, which includes SpunsealMessage, SslUnsealMessageStream, TlsDecryptHandler, and TlsDecryptMessag. Then, Ncrypt.dll, which includes SslDecryptpacket, SPSslDecryptPacket, and TlsDecryptPacket. Then, Bcrypt.dll, which includes BcryptDecrypt. Then, Bcryptprimitives.dll, which includes MSCryptDecrypt, MSBlockDecrypt, and AescbcDecrypt. 
     In an embodiment, a function may be a DecryptMessage( ) Function. This function may be used as follows:
         SECURITY_STATUS SEC_Entry   DecryptMessage(_in PCtxtHandle phContext,_inout PSecBufferDesc pMessage,_in ULONG MessageSeqNo,_out PULONG pfQOP).   CtxtHandle may be additional context information   CtxtHandle may access LSA_SEC_HANDLE by CtxtHandle {Void*P_vtable; LSA_SEC_HANDLE usercontext; . . . }   With LSA_SEC_HANDLE, NCRYPT_KEY_HANDLE may be accessed. CSslContext includes Cipher ID, ReadKey, WriteKey, and SessionID.   With NCRYPT_KEY_HANDLE, BCRYPT_KEY_HANDLE may be accessed. SSL_KEY_HANDLE may include hmac_key and bcrypt_key handle.   With BCRYPT_KEY_HANDLE, the shared secret (session key) may be obtained.   MSCRYPT_SYMMKEY_HANDLE includes the session key and the round key.       

       FIG. 7  is a simplified flowchart illustrating a process for extracting a shared secret using a shared library in accordance with an embodiment. A flow  700  may be a process that operates during and/or before an encryption protocol session. At  710 , an extraction module loads the shared library into an application. At  720 , the extraction module identifies any cryptographic structures in the application. At  730 , the extraction module hooks the cryptographic structures with extraction functions. Responsive to the cryptographic structures being called, at  740 , the execution module executes the extraction functions to identify the shared secret. At  750 , the extraction module extracts the shared secret. After  750 , the extraction module may securely transmit the shared secret to a security module. 
     In operational terms, and specifically one embodiment, an extraction module injects DLL into a process space of the application (e.g. web browser). To do this, the extraction module: uses GetProcessAddress to find the LoadLibrary function Kernel32.dll; places the string with the path to the injected DLL into the web browser process space via the VirtualAllocEx and WriteProcessMemory; and invokes the CreateRemoteThread to launch a thread in the web browser process space using the LoadLibrary as the thread method, passing the string allocated in above as the only argument. Then, the injected DLL: pre-loads the SCHANNEL.DLL into the process space; finds the base of the crypto data structures; and hooks the crypto functions of SCHANNEL.DLL with custom functions. Next, when the application requests crypto functions, the hooked functions are called which then: call the original SCHANNEL functions; inspect the data structure found above for the crypto key material, it may also find the master secret as well; and return the values returned by the original SCHANNEL functions. 
       FIG. 8  is a simplified flowchart illustrating a process for extracting a shared secret from a memory space in accordance with an embodiment. A flow  800  may be a process that operates during and/or before an encryption protocol session. At  810 , an extraction module monitors a network flow at a network layer. The extraction module is searching for an initiation of a handshake for the encryption protocol session. 
     At  820 , the extraction module identifies the initiation of the handshake of the encryption protocol session. Responsive to identifying the initiation, at  830 , the extraction module opens the memory space of a process initiating the encrypted protocol session. In one or more embodiments, the process may be an application. 
     At  840 , the extraction module identifies a shared secret in the encryption protocol session within the memory space of the process. At  850 , the extraction module extracts the shared secret. After  850 , the extraction module may transmit the shared secret to a security module. 
     In operational terms, and in particular, one embodiment, an extraction module may hook into TCP streams looking for ClientHello messages. When a ClientHello message is found, and until the key material for the session is found, all TLS messages are inspected. The SessionID is extracted for the ServerHello message. Before and after each packet is processed by the inspected process the process is queried via the EnumProcessModules and ReadProcessMemory to: find if SCHANNEL.DLL is loaded; find the base of the crypto data structures in SCHANNEL.DLL; and find the key material for the session id found in the ServerHello message, it may also find the pre-master and/or master secret as well. Once the key material is found the key material is sent to a security module. This process may be extended to find the key material in  FIG. 7 , including those that are statically linked, by searching the process space for the proper data structures. 
       FIG. 9  is a simplified flowchart illustrating a process for analyzing an encrypted network flow in accordance with an embodiment. A flow  900  may be a process that operates during an encryption protocol session. At  902 , a security module monitors the encrypted network flow between a first node and a second node, the network flow initiated from the first node. In an embodiment, the first node may be a client and the second node may be a server. The encrypted network flow travels both ways between the first node and the second node. 
     At  904 , the security module duplicates the encrypted network flow to form a copy of the encrypted network flow. At  906 , the security module decrypts the copy of the encrypted network flow using a shared secret. The shared secret associated with the first node and the second node. Both the first node and the second node know the shared secret. In an embodiment, the first node provides the shared secret. By knowing the shared secret, the security module can decrypt the network flow without interfering with the network flow. 
     At  908 , the security module scans the network flow copy for targeted data. Targeted data may be data that is targeted by the client, user, security module, firewall, security software, policy server, or other entity. 
     Additionally, in one or more embodiments, an extraction module may extract the shared secret from the first node before  902 . Additionally, in one or more embodiments, the security module may delay the encrypted network flow and forward the encrypted network flow as part of monitoring at  902 . In that embodiment, the security module would delay forwarding to give time to scan the copy of the network flow. Responsive to identifying targeted data in the network flow copy, the security module may terminate the encrypted network flow. 
       FIG. 10  also illustrates a memory  1002  coupled to processor  1000  in accordance with an embodiment. Memory  1002  may be any of a wide variety of memories (including various layers of memory hierarchy) as are known or otherwise available to those of skill in the art. The memory  1002  may include code  1004 , which may be one or more instructions, to be executed by processor  1000 . Processor  1000  follows a program sequence of instructions indicated by code  1004 . Each instruction enters a front-end logic  1006  and is processed by one or more decoders  1008 . The decoder may generate as its output a micro operation such as a fixed width micro operation in a predefined format, or may generate other instructions, microinstructions, or control signals that reflect the original code instruction. Front-end logic  1006  also includes register renaming logic  1010  and scheduling logic  1012 , which generally allocate resources and queue the operation corresponding to the convert instruction for execution. 
     Processor  1000  is shown including execution logic  1014  having a set of execution units  1016 - 1  through  1016 -N. Some embodiments may include a number of execution units dedicated to specific functions or sets of functions. Other embodiments may include only one execution unit or one execution unit that can perform a particular function. Execution logic  1014  performs the operations specified by code instructions. 
     After completion of execution of the operations specified by the code instructions, back-end logic  1018  retires the instructions of code  1004 . In one embodiment, processor  1000  allows out of order execution but requires in order retirement of instructions. Retirement logic  1020  may take a variety of forms as known to those of skill in the art (e.g., re-order buffers or the like). In this manner, processor  1000  is transformed during execution of code  1004 , at least in terms of the output generated by the decoder, hardware registers and tables utilized by register renaming logic  1010 , and any registers (not shown) modified by execution logic  1014 . 
     Although not illustrated in  FIG. 10 , a processing element may include other elements on a chip with processor  1000 . For example, a processing element may include memory control logic along with processor  1000 . The processing element may include I/O control logic and/or may include I/O control logic integrated with memory control logic. The processing element may also include one or more caches. 
       FIG. 11  illustrates a computing system  1100  that is arranged in a point-to-point (PtP) configuration according to an embodiment. In particular,  FIG. 11  shows a system where processors, memory, and input/output devices are interconnected by a number of point-to-point interfaces. 
     As illustrated in  FIG. 11 , system  1100  may include several processors, of which only two, processors  1102  and  1104 , are shown for clarity. Processors  1102  and  1104  may each include a set of cores  1103  and  1105  to execute multiple processes of a program. Processors  1102  and  1104  may also each include integrated memory controller logic (MC)  1106  and  1108  to communicate with memories  1110  and  1112 . The memories  1110  and/or  1112  may store various data such as those discussed with reference to memory  1112 . In alternative embodiments, memory controller logic  1106  and  1108  may be discrete logic separate from processors  1102  and  1104 . 
     Processors  1102  and  1104  may be any type of a processor such as those discussed with reference to processor  102  of  FIG. 1 . Processors  1102  and  1104  may exchange data via a point-to-point (PtP) interface  1114  using point-to-point interface circuits  1116  and  1118 , respectively. Processors  1102  and  1104  may each exchange data with a chipset  1120  via individual point-to-point interfaces  1122  and  1124  using point-to-point interface circuits  1126 ,  1128 ,  1130 , and  1132 . Chipset  1120  may also exchange data with a high-performance graphics circuit  1134  via a high-performance graphics interface  1136 , using an interface circuit  1137 , which could be a PtP interface circuit. In alternative embodiments, any or all of the PtP links illustrated in  FIG. 11  could be implemented as a multi-drop bus rather than a PtP link. 
     At least one embodiment, as disclosed herein, may be provided within the processors  1102  and  1104 . Other embodiments, however, may exist in other circuits, logic units, or devices within the system  1100  of  FIG. 11 . Furthermore, other embodiments may be distributed throughout several circuits, logic units, or devices illustrated in  FIG. 11 . 
     Chipset  1120  may be in communication with a bus  1140  via an interface circuit  1141 . Bus  1140  may have one or more devices that communicate over it, such as a bus bridge  1142  and I/O devices  1143 . Via a bus  1144 , bus bridge  1143  may be in communication with other devices such as a keyboard/mouse  1145  (or other input device such as a touch screen, for example), communication devices  1146  (such as modems, network interface devices, or other types of communication devices that may communicate through a computer network), audio I/O device  1147 , and/or a data storage device  1148 . Data storage device  1148  may store code  1149  that may be executed by processors  1102  and/or  1104 . In alternative embodiments, any portions of the bus architectures could be implemented with one or more PtP links. 
     The computer systems depicted in  FIGS. 10 and 11  are schematic illustrations of embodiments of computing systems that may be utilized to implement various embodiments discussed herein. It will be appreciated that various components of the systems depicted in  FIGS. 10 and 11  may be combined in a system-on-a-chip (SoC) architecture or in any other suitable configuration. For example, embodiments disclosed herein can be incorporated into systems such as, for example, mobile devices such as smart cellular telephones, tablet computers, personal digital assistants, portable gaming devices, etc. It will be appreciated that these mobile devices may be provided with SoC architectures in at least some embodiments. 
     Note that in certain example implementations, the security module and extraction module functions outlined herein may be implemented by logic encoded in one or more tangible media (e.g., embedded logic provided in an application specific integrated circuit (ASIC), digital signal processor (DSP) instructions, software (potentially inclusive of object code and source code) to be executed by a processor, or other similar machine, etc.). In some of these instances, a memory element can store data used for the operations described herein. This includes the memory element being able to store software, logic, code, or processor instructions that are executed to carry out the activities described in this Specification. A processor can execute any type of instructions associated with the data to achieve the operations detailed herein in this Specification. In one example, the processor could transform an element or an article (e.g., data) from one state or thing to another state or thing. In another example, the activities outlined herein may be implemented with fixed logic or programmable logic (e.g., software/computer instructions executed by a processor) and the elements identified herein could be some type of a programmable processor, programmable digital logic (e.g., FPGA, EPROM, EEPROM) or an ASIC that includes digital logic, software, code, electronic instructions, or any suitable combination thereof. 
     In one example implementation, the security module and extraction module may include software in order to achieve the security activities outlined herein. The security module and extraction module can include memory elements for storing information to be used in achieving the security activities, as discussed herein. Additionally, the security module and extraction module may include a processor that can execute software or an algorithm to perform the security activities, as disclosed in this Specification. These devices may further keep information in any suitable memory element (random access memory (RAM), ROM, EPROM, EEPROM, ASIC, etc.), software, hardware, or in any other suitable component, device, element, or object where appropriate and based on particular needs. Additionally, the security module and extraction module can be software, hardware, firmware or a combination thereof. Any of the memory items discussed herein (e.g., databases, tables, trees, caches, etc.) should be construed as being encompassed within the broad term ‘memory element.’ Similarly, any of the potential processing elements, modules, and machines described in this Specification should be construed as being encompassed within the broad term ‘processor.’ 
     Note that with the example provided above, as well as numerous other examples provided herein, interaction might be described in terms of two, three, or four elements. However, this has been done for purposes of clarity and example only. In certain cases, it may be easier to describe one or more of the functionalities of a given set of flows by only referencing a limited number of elements. It should be appreciated that the security module and extraction module (and their teachings) are readily scalable and can accommodate a large number of components, as well as more complicated/sophisticated arrangements and configurations. Accordingly, the examples provided should not limit the scope or inhibit the broad teachings of the security module and extraction module as potentially applied to a myriad of other architectures. 
     It is also important to note that the operations in the preceding flow diagrams illustrate only some of the possible scenarios and patterns that may be executed by, or within, a security module and extraction module. Some of these operations may be deleted or removed where appropriate, or may be modified or changed considerably without departing from the scope of the present disclosure. In addition, a number of these operations have been described as being executed concurrently with, or in parallel to, one or more additional operations. However, the timing of these operations may be altered considerably. The preceding operational flows have been offered for purposes of example and discussion. A security module and an extraction module provide substantial flexibility in that any suitable arrangements, chronologies, configurations, and timing mechanisms may be provided without departing from the teachings of the present disclosure. 
     Although the present disclosure has been described in detail with reference to particular arrangements and configurations, these example configurations and arrangements may be changed significantly without departing from the scope of the present disclosure. 
     The following examples pertain to embodiments in accordance with this Specification. One or more embodiments may provide a method for analyzing an encrypted network flow. The method may include: monitoring the encrypted network flow between a first node and a second node, the network flow initiated from the first node; duplicating the encrypted network flow to form a copy of the encrypted network flow; decrypting the copy of the encrypted network flow using a shared secret, the shared secret associated with the first node and the second node; and scanning the network flow copy for targeted data. 
     An example of an embodiment further comprises extracting the shared secret from the first node. 
     An example of an embodiment further comprises delaying the encrypted network flow; and forwarding the encrypted network flow. 
     An example of an embodiment further comprises, responsive to identifying targeted data in the network flow copy, terminating the encrypted network flow. 
     An example of an embodiment further comprises, responsive to identifying targeted data in the network flow copy, decrypting the encrypted network flow before forwarding using the shared secret; modifying the unencrypted network flow to remove the targeted data; and encrypting a modified network flow using the shared secret; and forwarding the modified network flow. 
     An example of an embodiment further comprises, wherein extracting the shared secret from the first node comprises: loading a shared library into an application on the first node, wherein the application is accessing the encrypted protocol session, and wherein the shared library allows access to an encryption protocol session through the application; and identifying the shared secret in the encryption protocol session. 
     An example of an embodiment further comprises, wherein extracting the shared secret from the first node comprises: monitoring a network flow at a network layer; identifying an initiation of a handshake of an encryption protocol session; responsive to identifying the initiation, opening a memory space of a process initiating the encrypted protocol session; and identifying the shared secret in the encryption protocol session within the memory space of the process. 
     An example of an embodiment comprises that the shared secret is at least one of a master secret, pre-master secret, session context. As used herein, the phrase “at least one of” may mean any one or combination of the list. For example, at least one of A, B, and C could mean A, B, or C, or any combination thereof. 
     An example of an embodiment further comprises limiting a number of encryption methods used to encrypt a network flow between the first node and the second node. 
     One or more embodiments provide a method, apparatus, and/or machine accessible storage medium for extracting a shared secret from a first node. The method includes loading a shared library into an application on the first node, wherein the application is accessing the encrypted protocol session, and wherein the shared library allows access to an encryption protocol session through the application; and identifying the shared secret in the encryption protocol session. 
     One or more embodiments provide a method, apparatus, and/or machine accessible storage medium for extracting a shared secret from a first node. The method includes monitoring a network flow at a network layer; identifying an initiation of a handshake of an encryption protocol session; responsive to identifying the initiation, opening a memory space of a process initiating the encrypted protocol session; and identifying the shared secret in the encryption protocol session within the memory space of the process. 
     An example of an embodiment further comprises extracting the shared secret from the memory space of the process. 
     An example of an embodiment further comprises sending the shared secret to a security module. 
     One or more embodiments provide an apparatus. The apparatus comprising a security module configured to monitor the encrypted network flow between a first node and a second node, the network flow initiated from the first node; duplicate the encrypted network flow to form a copy of the encrypted network flow; decrypt the copy of the encrypted network flow using a shared secret, the shared secret associated with the first node and the second node; and scan the network flow copy for targeted data. 
     An example of an embodiment further comprises an extraction module configured to extract the shared secret from the first node. 
     An example of an embodiment further comprises, wherein the security module is further configured to: delay the encrypted network flow; and forward the encrypted network flow. 
     An example of an embodiment further comprises, wherein the security module is further configured to: responsive to identifying targeted data in the network flow copy, terminate the encrypted network flow. 
     An example of an embodiment further comprises, wherein the security module is further configured to: responsive to identifying targeted data in the network flow copy, decrypt the encrypted network flow before forwarding using the shared secret; modify the unencrypted network flow to remove the targeted data; encrypt a modified network flow using the shared secret; and forward the modified network flow. 
     An example of an embodiment further comprises, wherein the extraction module being configured to extract the shared secret from the first node comprises the extraction module being configured to: load a shared library into an application on the first node, wherein the application is accessing the encrypted protocol session, and wherein the shared library allows access to an encryption protocol session through the application; and identify the shared secret in the encryption protocol session. 
     An example of an embodiment further comprises, wherein the extraction module being configured to extract the shared secret from the first node comprises the extraction module being configured to: monitor a network flow at a network layer; identify an initiation of a handshake of an encryption protocol session; responsive to identifying the initiation, open a memory space of a process initiating the encrypted protocol session; and identify the shared secret in the encryption protocol session within the memory space of the process. 
     An example of an embodiment further comprises, wherein the shared secret is at least one of a master secret, pre-master secret, session context. 
     An example of an embodiment further comprises, wherein the security module is further configured to: limit a number of encryption methods used to encrypt a network flow between the first node and the second node. 
     One or more embodiments provide at least one machine accessible storage medium having instructions stored thereon for analyzing an encrypted network flow, the instructions when executed on a machine, cause the machine to: monitor the encrypted network flow between a first node and a second node, the network flow initiated from the first node; duplicate the encrypted network flow to form a copy of the encrypted network flow; decrypt the copy of the encrypted network flow using a shared secret, the shared secret associated with the first node and the second node; and scan the network flow copy for targeted data. 
     An example of an embodiment further comprises instructions, when executed on the machine, cause the machine to: extract the shared secret from the first node. 
     An example of an embodiment further comprises instructions, when executed on the machine, cause the machine to: delay the encrypted network flow; and forward the encrypted network flow. 
     An example of an embodiment further comprises instructions, when executed on the machine, cause the machine to: responsive to identifying targeted data in the network flow copy, terminate the encrypted network flow. 
     An example of an embodiment further comprises instructions, when executed on the machine, cause the machine to: responsive to identifying targeted data in the network flow copy, decrypt the encrypted network flow before forwarding using the shared secret; modify the unencrypted network flow to remove the targeted data; and encrypt a modified network flow using the shared secret; and forward the modified network flow. 
     An example of an embodiment further comprises, wherein the instructions, when executed on the machine, cause the machine to extract the shared secret from the first node, further comprises instructions, when executed on the machine, cause the machine to: load a shared library into an application on the first node, wherein the application is accessing the encrypted protocol session, and wherein the shared library allows access to an encryption protocol session through the application; and identify the shared secret in the encryption protocol session. 
     An example of an embodiment further comprises, wherein the instructions, when executed on the machine, cause the machine to extract the shared secret from the first node, further comprises instructions, when executed on the machine, cause the machine to: monitor a network flow at a network layer; identify an initiation of a handshake of an encryption protocol session; responsive to identifying the initiation, open a memory space of a process initiating the encrypted protocol session; and identify the shared secret in the encryption protocol session within the memory space of the process. 
     An example of an embodiment further comprises, wherein the shared secret is at least one of a master secret, pre-master secret, session context. 
     An example of an embodiment further comprises instructions, when executed on the machine, cause the machine to limit a number of encryption methods used to encrypt a network flow between the first node and the second node.