Abstract:
A technique for defining a system with enhanced trust is disclosed, in which an immediate contact is made with the user on the enhanced trust system when a compromise is first detected. The service contacts the compromised user and asks for confirmation of the results. As a result, the true user on the enhanced trust machine is able to preclude a login or preclude a password change. In a first embodiment of the invention, an enhanced trust machine is a machine where the user is currently logged in at the time that the less trusted machine attempts a login. A second embodiment of the invention comprehends an enhanced trust machine where the user has logged in repeatedly over a course of numerous weeks, as compared with a lesser trusted machine that the user has never logged into before and which is now asking for a change of the password.

Description:
[0001]     This application is a continuation of U.S. patent application Ser. No. 10/323,230, filed Dec. 18, 2002 (Attorney Docket No. AOL0028). 
     
    
     FILED OF THE INVENTION  
       [0002]     The invention relates to computer security. More particularly, the invention relates to a trusted communication channel to combat user name/password theft.  
       BACKGROUND OF THE INVENTION  
       [0003]     Discussion of the Prior Art  
         [0004]     Malicious individuals employ various schemes to steal user name and password pairs from real users in the computer system. A common scenario for such theft is to “spoof” an official page of a system and lure a user into entering a user name and password into the system. The attacker then logs in and changes the compromised password to preclude use thereof by the true user, and ensure completion of the theft. In some cases, the attacker must immediately use the stolen password, for example where there is a time sensitive component, such as a Secure ID component.  
         [0005]      FIG. 1  is a schematic flow diagram that shows a user  10  logged in to a system  12  (as indicated by numeric designator ( 1 )). A malicious individual  18  generates a message  14 , for example indicating to the user  10  that they might win a corporate incentive and that details with regard to the incentive are provided at a website, e.g. “go to xyz.” The message is provided to the user  10  as indicated on  FIG. 1  by the numeric designator ( 2 ).  
         [0006]     The user follows the link, as indicated on  FIG. 1  by the numeric designator ( 3 ). At the end of the link, there is a page  16  which the user had been lead to believe is within the company system, i.e. which is a trusted page, but which is in fact an outside, i.e. untrusted, page. The user is asked to type in the user name and/or password to verify that they are entitled to receive the reward promised at the site. Unwittingly, the user enters this information and the malicious individual is thereafter able to capture the user&#39;s name and password, as indicated on  FIG. 1  by the numeric designator ( 4 ). Thereafter, the malicious individual can log into the system, change the user&#39;s password, and steal information from the account. This is indicated on  FIG. 1  by the numeric designator ( 5 ).  
         [0007]     It would be advantageous to provide a technique for using a trusted communication channel to combat user name/password theft.  
       SUMMARY OF THE INVENTION  
       [0008]     The invention provides a technique for defining a system with enhanced trust. In one embodiment of the invention, an immediate contact is made with the user on the enhanced trust system when a compromise is first detected, e.g. when there is a second log in attempt from another location. Using trusted communications channels, the service can often contact the compromised user and ask for confirmation of the results, i.e. to change password or login, from a reduced trust machine. As a result, even if an attacker steals a password, the true user on the enhanced trust machine is able to preclude a login or preclude a password change. In each case, if the user of the enhanced trust machine does not respond within some short period of time, then a less trusted machine can be allowed to proceed.  
         [0009]     The invention comprehends an enhanced trust machine, which is a machine where the user is currently logged in at the time that the second, less trusted machine attempts a login. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0010]      FIG. 1  is a schematic flow diagram showing a technique that is used to “spoof” a user name and password;  
         [0011]      FIG. 2  is a flow diagram showing a technique for using enhanced trust to combat user name and password theft according to a first embodiment of the invention; and  
         [0012]      FIG. 3  is a flow diagram showing a system for using enhanced trust to combat user name and password theft according to a second embodiment of invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]     In general, for security, there are three classes of identification; 
        What you have;     What you know; and     What you are.        
 
         [0017]     Examples of the first item include possession of a specific piece of hardware; the second item is exemplified by a password; and the third item is a biometric indicator, such as fingerprint or voiceprint. The invention operates with the assumption that a machine that is used extensively by a user is tagged as a machine that has enhanced trust. For example, if a user comes to their workstation everyday and uses the same machine, then the system develops experience with regard to the user&#39;s work patterns and expects that that machine is used by the user. Thus, the trust of the user being at that machine is enhanced. In the preferred embodiment of the invention, this is done by recording the number of times the given user has logged in from a given machine, and storing evidence of that history locally, possibly signed by a service to preclude forgery. At a minimum, the fact that a machine has a current active login assures that the machine is relatively more trusted than a machine that has neither a current, nor prior login by a given user. Specifically, the invention tags machines to create an additional “what you have” to add to the current password “what you know.” Modern authentication theory suggests that two out of these three classes of identification are needed for significant assurance of identity. The invention recognizes this aspect of security theory and uses the concept of tagging and verification to prevent forged authentication, such as stolen passwords.  
         [0018]     It is difficult, if not almost impossible, to prevent spoofing of official pages, for example where innocent victims are lured into supplying user names and passwords. One aspect of the invention uses the provisions of online services, such as AOL&#39;s AIM service, to make an immediate machine-to-human connection to the most likely valid user. The fact that many companies use a time-varying password generation scheme, such as secure ID, to generate a random number as a function of the time and day, provides assurance that an attacker must immediately use a compromised password. However, the invention is also useful in other password generation schemes. Because most passwords are comprised while the users are still online, the invention takes advantage of the fact that it is possible to reach the online user.  
         [0019]     With credit cards, charges that are exceptional in nature often induce a credit card agency to contact the person directly for additional authentication. In this invention, instant messaging technology is used as the contact mechanism. One embodiment of the invention uses current and prior login history to establish a pattern of actions, i.e. experience, and detects suspicious logins and password changes. The public key system commonly known as PGP (Pretty Good Privacy) uses a history of communications to establish a trust relationship with a person and the person&#39;s key. Thus, PGP includes the notion of basing trust on history. However, the invention herein recognizes that experiential information may be applied to password authentication and, when combined with machine tagging such as writing signed logs to a disk to identify a relative trust of a piece of hardware, that a ability to prevent spoofing of a system is provided. The result of this sort of defense almost completely precludes theft of internal passwords. It also gives the company employing such a system a rapid notification about such theft attempts, which can then be applied to attempt to blockade further efforts. For example, attempts to use stolen accounts from related blocks of IP addresses machines are then implicitly listed as being untrustworthy.  
         [0020]     Thus, the invention comprises technology for defining a machine as being a machine having enhanced trust, wherein a messaging technology is used to make immediate contact with the user on the enhanced trust system. Using such communications channels, the invention provides a mechanism that can contact the compromised user and ask for confirmation for results, i.e. to change a password or even to login, with regard to a reduced trust machine. Thus, even if an attacker steals a password, the true user on the enhanced trust machine is able to preclude a login or preclude a password change. In each case, if the user on the enhanced trust machine does not respond within some short period of time, then a less trusted machine is allowed to proceed, should this be desired.  
         [0021]     The invention presently comprises an enhanced trust machine, which is a machine where the user is currently logged in at the time a second, less trusted machine attempts a login.  
         [0022]      FIG. 2  is a flow diagram of a preferred embodiment of the invention in which a user is logged into a system ( 100 ). If a second login attempt is made ( 102 ), then the system sends an Instant Message to the user logged in at the first, enhanced trust location ( 104 ) to verify that the second login is authorized ( 106 ). If the user of the enhanced trust machine confirms that the user of the less trusted machine is properly permitted to login, for example by retyping a password, or typing a special password, then the less trusted machine is allowed to login ( 110 ). Likewise, if there is a timeout, indicating that the user logged in at the initial machine is not responding, for example because they have walked away from the machine and are now walking to another location, then the user is typically allowed to login as well. If the user responds to the instant message that there is no permission or no desire to login at the second, less trusted machine, then second login is refused ( 108 ). In this case, the second machine may be added to a filter list which blocks the machine or gives rise to an investigation the machine as having a suspicious IP address ( 112 ).  
         [0023]      FIG. 3  is a flow diagram which shows an alternative embodiment of the invention in which the concept of trust is based upon experience. In  FIG. 3 , a user is logged in ( 100 ) when a second login attempt is made ( 102 ). In this case, the system looks to see if the user action is consistent with system experience ( 200 ). For example, the system may determine that the machine at which the user is currently logged in is one that the user has used everyday over a period of time and that is therefor a trusted machine, while the second login attempt is being made from a less trusted machine, i.e. a machine from which the user has never logged in before. It may be that the user is in fact logging in from the second machine legitimately. In such case, the mechanism outlined in connection with  FIG. 2  above can be applied, in which the system sends an instant message to the user at the first login to verify that the second login should be permitted ( 104 ). Thereafter, the mechanism is applied as set forth, for example in  FIG. 2  ( 204 ). If the user action is consistent with experience, then the second login is allowed ( 202 ).  
         [0024]     The concept of experiential trust can be based upon one or more of many factors, including the use of a particular machine over time by a user, the use of the system by the user within a particular geographic region, i.e. the user has never logged in outside of the United States, the use of a particular machine at given times of day, i.e. the user has never attempted to login at 4:00 AM, or any other relevant factors. The forgoing situations are provided by way of example, and those skilled in the art will appreciate the various other bases for experience may be incorporated into this system. Furthermore, while the invention is described in connection with the use of an instant messaging mechanism for notifying a user of a trusted machine that there is an attempt to access the system using a less trusted machine, those skilled in the art will appreciate that the mechanism need not be instant messaging, but could involve the use of any other channel, such as a pager, a telephone, or other messaging systems. A key point is that the user of the trusted machine is notified promptly that an attempt is being made to login at a remote location. Further, while the invention is described as providing notification to the user at a trusted machine when an attempt is made to change a password or login identification from an untrusted machine, the system may tolerate the use of an untrusted machine so long as no attempt is made to change the password or user name. In such case, any attempt to change the password or user name requires the use of some further evidence of trustworthiness at the less trusted machine, for example the user would have to provide a further password that had previously been entered into the system but which has not been previously used as part of the current session. Absent this further proof, an instant message is sent to the user at the trusted machine and the mechanism herein described is invoked.  
         [0025]     Although the invention is described herein with reference to the preferred embodiment, one skilled in the art will readily appreciate that other applications may be substituted for those set forth herein without departing from the spirit and scope of the present invention. Accordingly, the invention should only be limited by the claims included below.