Abstract:
A method, system and apparatus for detecting and preventing content distribution site impersonation. In this regard, a method for detecting and preventing content distribution site spoofing can include the steps of loading a markup language document and a corresponding digital signature for processing and ensuring that the digital signature originates from a pre-specified source of the markup language document incorporated within the markup language document. The method further can include the steps of dynamically computing a hash value for the markup language document and comparing the dynamically computed hash value to a hash value encrypted within the digital signature. Finally, the method can include the step of detecting content distribution site spoofing either if the digital signature does not originate from the pre-specified source, or if the dynamically computed hash value does not match the hash value encrypted within the digital signature.

Description:
BACKGROUND OF THE INVENTION 
     1. Statement of the Technical Field 
     The present invention relates to the field of data communications security and encryption and more particularly to signing and validating network distributable content. 
     2. Description of the Related Art 
     Malicious computer users, commonly referred to as “hackers”, have grown bolder each day, adding to their growing repertory of hacking exploits while leveraging new combinations of old exploits to create new threats of ever increasing sophistication. Each new threat generally attempts to perpetrate an on-line fraud of which the computing public is to remain unaware. One type of on-line scam which has become prevalent involves the creation and wide-scale distribution of an electronic message (e-mail) that appears to the casual user to have originated from a trusted party. 
     Typically, the message within the email can demand that the recipient select a hyperlink within the e-mail, or can cajole the recipient into selecting the hyperlink. Unbeknownst to the recipient, the hyperlink can lead to a content distribution site such as a Web site designed to obtain personal and confidential information. As an alternative, the message can ask the recipient to “re-enter” personal information such as a user identifier, password, credit card number or account number. As yet another alternative, the e-mail message can threaten to terminate the e-mail account of the recipient, assign the recipient a bad credit rating, or charge the credit card of the recipient unless the recipient provides certain personally identifying information. 
     As it will be apparent to the skilled artisan, the foregoing e-mail scam represents a confidence game having the sole purpose of persuading recipients to voluntarily provide personal information which later can be used for various fraudulent purposes. As noted, the hyperlink in the e-mail message typically directs the e-mail message recipient to a hacker-operated content distribution site which impersonates a content distribution site of a trusted party known and expected by the recipient. Non-email schemes for directing a victim to a hacker-operated content distribution site also are known and include Web advertising, search engine stuffing, “bogus” news or discussion group postings, or even an innocuous-appearing security site created by the hacker helpfully purporting to direct the user to an official bug-fix site. 
     Central to the hacker scam is the ability of the hacker to convincingly impersonate the trusted content distribution site. The degree of realism depends upon the specific techniques used by the hacker, as well as the gullibility of the user. The effectiveness of the sham also can vary with the version, patch level, and configuration settings of a content browser. Several variations exist in respect to this scam. For instance, in one variation, a complete copy of a Web site can be created and hosted at a different Web site controlled by the hacker. The link to the spoof Web site can be constructed to appear as if the link refers to the legitimate site, though critical portions of the link will cause the misdirection of the link to the hacker controlled site. In another variation, the spoof content distribution site can be hosted at a domain which is but a misspelled derivative of the actual content distribution site. 
     U.S. patent application Publication No. 2002/0124172 to Manahan for METHOD AND APPARATUS FOR SIGNING AND VALIDATING WEB PAGES (hereinafter, “Manahan”) addresses the general problem of spoofing a Web site. In the Manahan publication, a Web page can be digitally signed using a private key to provide a digital signature. The Web page, digital signature and a digital certificate can be transmitted to the Web content browser of an end user which can use the digital certificate and digital signature to verify the content of the Web page. Nevertheless, the technology of the Manahan publication cannot account for the spoofing of the Web site itself from which the content originates. 
     Notably, the technology disclosed in the Manahan publication protects the integrity of the content, but does nothing to assure that the content is delivered from a known server. That is, in the Manahan publication, if signed content simply is copied intact and re-hosted on a different server controlled by a hacker, that server will distribute the original content and signature, which the user&#39;s browser will verify as being correct. In this situation the user&#39;s browser will not detect the danger that any personal information entered in response to the spoofed content is placed into the hands of an untrusted party, rather than the content owner who signed the content. In other words, where a victim inadvertently visits a spoofed Web site, the Manahan arrangement will be ineffective to protect the victim from the scam. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the deficiencies of the art in respect to content distribution site spoofing and provides a novel and non-obvious method, system and apparatus for detecting and preventing content distribution site impersonation. In this regard, a method for detecting and preventing content distribution site spoofing can include the steps of loading a markup language document and a corresponding digital signature for processing and ensuring that the digital signature originates from a pre-specified source of the markup language document incorporated within the markup language document. 
     The method further can include the steps of dynamically computing a hash value for the markup language document and comparing the dynamically computed hash value to a hash value encrypted within the digital signature. Finally, the method can include the step of detecting content distribution site spoofing either if the digital signature does not originate from the pre-specified source, or if the dynamically computed hash value does not match the hash value encrypted within the digital signature. 
     The loading step can include the step of extracting the digital signature from the markup language document. Also, the ensuring step can include the step of comparing a domain for the digital signature to a domain embedded in a field in the markup language document to ensure that the digital signature originates from the embedded domain. Notably, the method additionally can include the step of further ensuring that the markup language document originates from a host server at the pre-specified source. Similarly, the method additionally can include the step of further ensuring that the markup language document originates from a host server at the embedded domain. Finally, the method additionally can include the steps of extracting at least one Internet Protocol address from the markup language document and ensuring that the markup language document originates from a host server having an Internet Protocol address included among the extracted Internet Protocol addresses. 
     In a preferred aspect of the invention, an embedded slogan can be retrieved from a digital certificate associated with the markup language document. Subsequently, the markup language document can be modified to render the embedded slogan near a portion of the markup language document referencing a pre-specified slogan. In this way, to the extent that the slogan is not rendered near the portion of the markup language document referencing the pre-specified slogan, it will be visually apparent to the end user that the markup language document may have been spoofed. In any case, responsive to detecting content distribution site spoofing, the markup language document can be modified to render a warning message. 
     Additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The aspects of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. The embodiments illustrated herein are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown, wherein: 
         FIG. 1  is a schematic illustration of a system, method and apparatus for detecting and preventing content distribution site spoofing; 
         FIG. 2  is a block diagram illustrating a markup language document configured for use in the content distribution site spoofing detection and prevention system of  FIG. 1 ; and, 
         FIG. 3  is a flow chart illustrating a process for detecting and preventing content distribution site spoofing in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is a method, system and apparatus for detecting and preventing content distribution site spoofing. In accordance with the present invention, a markup language document such as those distributed through content distribution sites such as Web sites can be digitally signed prior to transmission to a content consumer. Additionally, a source address can be embedded in the markup language document which corresponds to the source of the markup language document. Upon receipt of the digitally signed markup language document, the content consumer can process both the digital signature and the embedded source address to confirm the integrity and validity of the markup language document. Failing validation, a warning indicator perceptible by a human sense, such as sight or sound, can be rendered as part of or in association with the content to warn the content consumer of possible site spoofing. 
     In more particular illustration of the foregoing inventive arrangement,  FIG. 1  is a schematic illustration of a system, method and apparatus for detecting and preventing content distribution site spoofing. As shown in  FIG. 1 , a content distribution site  110  can be configured to deliver content to one or more content consumers  130  over a data communications network  120 . The content distribution site  110 , for example a Web site or other markup language distribution site, can include a content server  115  configured to respond to content requests from content consumers  130  by retrieving requested content and transmitting the requested content over the data communications network  120  to the requesting content consumers  130 . The content consumers  130 , in turn, can include a content browser  160  configured for rendering requested content for presentation to an end user in a manner perceptible to one or more human senses. 
     The content server  115  can be coupled to or can include server-side page security logic  135  programmed to configure a markup language document  125  for use in detecting and preventing content distribution site spoofing. In this regard, the server-side page security logic  135  can insert in the markup language document  125  one or more fields of security information, including addressing data  155  which can identify the address or identity of the content distribution site  110 . For instance, the addressing data  155  can include a domain associated with the content distribution site  110 , or one or more Internet protocol addresses associated with the content distribution site  110 . The markup language document  125  further can include a reference to a certificate of authenticity as well as a source slogan (not shown) indicative of the source of the markup language document  125 . 
     In more particular illustration,  FIG. 2  is a block diagram depicting a markup language document which has been configured for use in the Web site spoofing detection and prevention system of  FIG. 1 . The markup language document  200  can include markup language annotated content  250  so that the content  250  can be rendered by a content browser. Within the markup language document  200 , however, one or more additional fields can be embedded so as to provide enhanced security for combating content distribution site spoofing. 
     Specifically, the expected domain name  210  of the host server for the markup language document  200  can be specified, as can one or more associated Internet Protocol addresses  220  of one or more host servers for the markup language document. Moreover, a digital certificate  240  can be included which can refer to the authentic source of the markup language document  200 . Finally, a digital signature  230  can be included which can be an encrypted form of a hash value produced for the content of the markup language document  200  (excluding the digital signature  230  and digital certificate  240 ). In this way, page security logic coupled to or included within a content browser can be programmed to extract the foregoing fields  210 ,  220 ,  230 ,  240  to confirm the integrity of the content and source of the markup language document  200 . 
     In this regard, returning now to  FIG. 1 , when preparing a markup language document  125  for distribution to requesting content consumers  130 , the server-side page security logic  135  can compute a hash value  140  for the markup language document  125 . The computed hash  140  further can be encrypted using a private key  145  associated with the content distribution site  110  and certificate  240  to produce a digital signature  150  for the markup language document  125 . Accordingly, when requested by a content consumer  130 , the content server  115  can forward to the requesting content consumer  130  each of the markup language document  125 , the generated digital signature  150  and the addressing information  155  embedded in the markup language document  125 . This addressing information  155  should match the source address field in the headers of data packets that carry the markup language document  125  over network  120 . 
     Each of the content consumers  130  which have been configured for use in the Web site spoofing and detection system can include a content browser  160  coupled to or containing complementary client-side page security logic  165 . The client-side page security logic  165  can compute a dynamic hash value  175  for a received markup language document  125 . The client-side page security logic  165  further can retrieve a public key  170  associated with the private key  145  used to compute the digital signature  150  for content  125  through information provided by a certificate authority  190  which process is well-known in the art. The public key  170  can be used to decrypt the digital signature  150  to retrieve the computed hash  140 . 
     The client-side page security logic  165  can compare the computed hash  140  to the dynamic hash  175  to verify the integrity of the content of the markup language document  125 . Additionally, the client-side page security logic  165  can ensure that the source of the markup language document  125  matches the addressing data  155  embedded in the markup language document  125 . If the integrity of the markup language document  125  can be determined by the client-side page security logic  165 , a sensory indicator  180  can be rendered within or in association with the markup language document  125 . 
     Moreover, as an added measure an embedded source slogan (not shown) can be extracted from the markup language document  125  and rendered within or in association with the markup language document  125  to match a specified source slogan incorporated as part of the markup language document  125 . To the extent that the specified source slogan does not match the embedded source slogan (not shown) at the time of rendering the markup language document  125  in the content browser  160 , it will be apparent to the end user that the integrity of the markup language document  125  has been compromised. Alternatively the source slogan can be a markup language fragment, and the markup language document  125  can contain incomplete markup to be completed by insertion of the markup language fragment, such that if the proper fragment is not inserted, the markup rendering will be defective in a manner that is readily apparent to the user of content browser  160 . In this way, an optimal selection of blatant sensory cues can be provided to the end user within the markup language document  125  to combat content distribution site spoofing. 
     In further illustration,  FIG. 3  is a flow chart illustrating the exemplary operation of the client-side page security logic. Though the flow chart includes a specific combination of remedial and prophylactic measures for detecting and preventing the spoofing of a content distribution site, the invention is not so limited to the precise arrangement reflected by the flow chart of  FIG. 3 . Rather, the skilled artisan will recognize any number effective combinations of measures which can be utilized in furtherance of the detection and prevention of content distribution site spoofing. As such, the scope of the present invention is best reflected in the language of the claims rather than in the exemplary embodiment illustrated herein. 
     Referring to  FIG. 3  and beginning in block  305 , a markup language document can be received for processing the client content browser. In block  310 , the domain name included in the markup language document can be extracted and compared to the domain name of the host server from which the markup language document had been retrieved. If in decision block  315  a match cannot be confirmed, in block  385  the markup language document can be rendered with a prominently positioned invalidity message, such as “WARNING—The Authenticity Of This Document CANNOT Be Confirmed.” Notably, the message can be posted as part of the rendered content, or as a separate document in a separate window or frame in the content browser. 
     Returning to decision block  315 , if a match can be confirmed, in decision block  320  the markup language document can be inspected to determine if one or more Internet Protocol addresses have been embedded in the markup language document. If so, in decision block  325  the Internet Protocol address of the host server which provided the markup language document (typically obtained from the source address field in the transport header of data packets carrying the markup language) can be compared to one or more of the embedded addresses seeking a match. As before, if a match cannot be confirmed, in block  385  the markup language document can be rendered with a prominently positioned invalidity message. Otherwise, the process can continue in decision block  330 . 
     In decision block  330 , the markup language document can be inspected to determine if a certificate has been embedded in the markup language document. If so, in block  335  the domain name to which the certificate has been issued can be compared to the domain name field embedded in the markup language document. If in decision block  340  the domain name cannot be matched, an invalidity message can be rendered in block  385 . Returning to decision block  330 , if a certificate has not been embedded in the markup language document, a certificate can be retrieved from a third party certificate authority or public directory server in block  345  by passing the embedded domain name to the third party certificate authority or public directory server. 
     In either case, in decision block  350  it can be determined if the certificate trust chain is OK and that the certificate has not been self-signed by the source of the markup language document. If so, an invalidity message can be rendered in block  385 . Otherwise, in block  355 , a hash value can be computed for the markup language document excluding the digital certificate field and digital signature field of the markup language document. In block  360  the digital signature can be decrypted using the public key specified by the certificate. In decision block  365 , if the hash within the decrypted signature does not match the computed hash, again an invalidity message can be rendered in block  385 . Otherwise, a validity message can be rendered in block  370 . 
     Notably, to discourage hackers from exploiting the client-side page security logic by re-signing content with hacker originated certificates, the certificate field of the markup language document can include an embedded source slogan such as a trade phrase which the certificate authority can verify at the time of certificate issuance. Consequently, in block  375  the trade phrase can be inserted in place of the document signature markup and the markup language document itself can include the trade phrase so that any inconsistency will be recognizable when, in block  380 , the document markup is rendered in the content browser to produce the page. Alternatively the source slogan can be a markup language fragment designed to complete an incomplete markup language document, that when absent or incorrect results in an obvious defective rendering, and when present and correct results in completion and a perceptually correct rendering. The source slogan as yet another alternative can be an image or a portion of an image, that when correctly combined with the markup language document yields an image (such as a trademark) certified by a certificate authority at the time of certificate issuance, or when absent yields an obviously defective rendering of the image. 
     The present invention can be realized in hardware, software, or a combination of hardware and software. An implementation of the method and system of the present invention can be realized in a centralized fashion in one computer system, or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system, or other apparatus adapted for carrying out the methods described herein, is suited to perform the functions described herein. 
     A typical combination of hardware and software could be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein. The present invention can also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which, when loaded in a computer system is able to carry out these methods. 
     Computer program or application in the present context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following a) conversion to another language, code or notation; b) reproduction in a different material form. Significantly, this invention can be embodied in other specific forms without departing from the spirit or essential attributes thereof, and accordingly, reference should be had to the following claims, rather than to the foregoing specification, as indicating the scope of the invention.