Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 1 of 17
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`Exhibit 2
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`

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`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 2 of 17
`Casesv7evoseso-vHA DocemTLTA0TAA
`
`US008141154B2
`
`US 8,141,154 B2
`(10) Patent No:
`a2) United States Patent
`Gruzmanetal.
`(45) Date of Patent:
`Mar.20, 2012
`
`
`2001/0005889 Al*
`2002/0116635 Al
`2004/0133796 Al
`2004/0153644 Al
`2004/0158729 Al
`2005/0108562 Al
`2005/0149749 Al*
`2006/0015940 Al
`2006/0161981 Al
`2007/0016948 Al
`* cited by examiner
`
`6/2001 Albrecht ........ 713/201
`
`8/2002 Sheymov...
`726/24
` 8/2004 McCorkendale et al. .... 713/156
`7/2004 Cohen etal. wo...
`w 726/24
`
`
`
`8/2004 SZOL vce 713/190
`726/23
`.
`5/2005 Khazan etal.
`
`. 713/200
`..
`7/2005 Van Brabant
`
`wa 726/22
`...
`1/2006 Zamir ctal.
`....
`w 726/22
`7/2006 Shethetal.
`
`1/2007 _Dubrovsky etal.
`............ 726/22
`
`Primary Examiner — Ponnoreay Pich
`(74) Attorney, Agent, or Firm — Dawn-Marie Bey; King &
`Spalding LLP
`
`ABSTRACT
`(57)
`A method for protecting a client computer from dynamically
`generated malicious content, including receiving ata gateway
`computer content being sent to a client computer for process-
`ing, the content including a call to an original function, and
`the call including an input, modifying the content at the
`gateway computer, including replacing the call to the original
`function with a correspondingcall to a substitute function, the
`substitute function being operational to send the input to a
`security computer for inspection, transmitting the modified
`content from the gateway computer to the client computer,
`processing the modified contentat the client computer, trans-
`milling the inputto the securily computer for inspection when
`the substitute function is invoked, determiningat the security
`computer whetherit is safe for the client computer to invoke
`the original function with the input, transmitting an indicator
`of whether it is safe for the client computer to invoke the
`original function with the input, from the security computer to
`the client computer, and invoking the original function at the
`client computer with the input, only if the indicator received
`from the security computer indicates that such invocation is
`sate. A system and a computer-readable storage medium are
`also described and claimed.
`
`12 Claims, 5 Drawing Sheets
`
`(54) SYSTEM AND METHOD FOR INSPECTING
`DYNAMICALLY GENERATED EXECUTABLE
`CODE
`
`(75)
`
`.
`Inventors: David Gruzman, Ramat Gan (IL);
`Yuval Ben-Itzhak, Tel Aviv (IL)
`:
`:
`Emi
`(73) Assignee: Finjan,Inc. (IL)
`(*) Notice:
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`US.C. 154(b) by 0 days.
`
`(21) Appl. No.: 12/814,584
`
`(22)
`(65)
`
`Filed:
`
`Jun. 14, 2010
`Prior Publication Data
`US 2010/0251373 Al
`Sep. 30, 2010
`
`(51)
`
`Int. Cl.
`(2006.01)
`GO6F 11/00
`(52) US. Ch we 726/22, 726/23; 726/24; 713/188
`(58) Field of Classification Search ..........0.0...0. None
`See application file for complete search history.
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`AAAA
`
`10/1994 Rosenthal 0.0... 726/24
`5,359,659
`10/1999
`. 726/23
`5,974,549
`
`11/1999
`. 726/13
`5,983,348
`
`7/2000
`. 726/24
`6,092,194
`
`. 726/23
`12/2000
`6,167,520 A
`
`Bl
`. 726/24
`8/2001
`6,272,641
`
` .» 7206/5
`Bl
`8/2005
`6,934,857
`w TLL/118
`11/2005
`6,965,968 B1
`
`B2
`« 717/146
`4/2007 Souloglouctal.
`.
`7,203,934
`
`10/2007 Bertmanetal. ......0.. 726/23
`7,287,279 B2
`
`12/2007 Ben-Itzhak ou... 726/24
`7,313,822 B2
`.......0000000.. TAT/174
`6/2010 Badenell
`7,739,682 B1*
`7,836,504 B2* 11/2010 Rayetal. ou. 726/24
`
`
`
`
`
`
`
`
`
`FINJAN-JN 002025
`
`
`
`ORIGINAL INCOMING
`CONTENT
`
`
`
` YBIAIQOWLMANI-INSLNOD
`
`
`MELLUWSNVELLAVAELLYS
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`Y3AIZOIYLNIMO
`
`INDICATOR TO CLIENT
`MODIFIED INPUT YOSSISONdLNSLNOS
`
`B COMPUTER OF SAFE INPUT
`
`
`
` 410
`“\ MODIFIED CONTENT,
`
`
`
`MOLOZAISNILN
`
` MBLUNSNVYLLNAND
`
`
`YBAISOSYAVMALYD
`
`
`
`INPUT, CLIENT ID
`
`
`
`405—+
`GATEWAY COMPUTER
`CLIENT COMPUTER
`
`
`
`

`

`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 3 of 17
`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 3 of 17
`
`U.S. Patent
`
`Mar.20, 2012
`
`Sheet 1 of 5
`
`US 8,141,154 B2
`
`
`
`
`145
`CONTENT PROCESSOR
`
`CLIENT RECEIVER
`
`ORIGINALCONTENT
`
`ORIGINALCONTENT
`
` ORIGINALCONTENT.
`
`
`
` GATEWAY TRANSMITTER
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` CONTENT PROCESSOR
`FIG.1(PRIORART)
`
`GATEWAY TRANSMITTER
`
`CONTENT INSPECTOR
`
`170
`
` =
`
`CONTENT INSPECTOR
`
`GATEWAY TRANSMITTER
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`GATEWAY RECEIVER
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`FINJAN-JN 002026
`
`

`

`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 4 of 17
`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 4 of 17
`
`U.S. Patent
`
`Mar.20, 2012
`
`Sheet 2 of 5
`
`US 8,141,154 B2
`
`CLIENT TRANSMITTER
`
`
` INPUT, CLIENT [D SECURITY RECEIVER
`
`
`DATABASEOFCLIENT
`
`SECURITYPOLICIES
` CONTENT PROCESSOR
`MODIFIER INPUT INSPECTOR INPUT
`
`
`
`
`
` MODIFIED INPUT
`
`
`SECURITY TRANSMITTER
`INDICATOR TO CLIENT
`
`COMPUTEROF SAFE iNFUT
`
`m=
`
`CONTENT MODIFIER
`
`
`
`
`GATEWAY RECEIVER CONTENT
`
`ORIGINALINCOMING
`
`220
`
`FIG.2
`
`FINJAN-JN 002027
`
`

`

`RECEIVE CONTENT FROM
`NETWORKINTENDED FOR CLIENT
`COMPUTER
`
`
`
`OF FUNCTION CALLS
`
`FUNCTION CALLS FOUND
`IN CONTENT?
`
`
`
`
`REPLACEORIGINAL FUNCTION
`
`CALLS IN CONTENT WITH
`SUBSTITUTE FUNCTION CALLS
`
`312
`
`316
`
`TRANSMIT CONTENT TO CUENT
`
`
`FOR PROCESSING
`
`
`
`320
`
`FROM CLIENT COMPUTER 340
`
` SCAN CONTENT FOR PRESENCE
`
`FUNCTION CALLS
`
`
`INSPECTION REPLACE ORIGINAL FUNCTION
`SUBSTITUTE FUNCTION CALLS
`
`
`RECEIVE SAFETY INDICATOR AND
`
`
`
`SCAN INPUT TO DETERMINE
`MODIFIED INPUT FROM SECURITY
`
`SECURITY PROFILE
`
`
`COMPUTER
`
`RETRIEVE SECURITY POLICY FOR
`INDICATOR = TRUE?
`CLIENT COMPUTER
`
`
`
`YES
`360
`WITH MODIFIED INPUT 364
`
`
`
`
`SET INDICATOR = TRUE
`
`
`ars
`
`
`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 5 of 17
`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 5 of 17
`
`U.S. Patent
`
`Mar.20, 2012
`
`Sheet 3 of 5
`
`US 8,141,154 B2
`
`je— GATEWAYCOMPUTER —|
`
`-~ CLIENTCOMPUTER —|
`
`RECEIVE CONTENT FROM
`GATEWAY COMPUTER
`
`| SECURITY COMPUTER —|
`
`RECEIVE INFUT AND CLIENTID
`
`CONTINUE TO PROCESS
`CONTENT
`
`SCAN INPUT FOR PRESENCE OF
`
`wa
`
`FUNCTION CALLS FOUND
`
` IN INPUT? INVOKE SUBSTITUTE FUNCTION
`
`TRANSMIT INPUT AND CUENT ID
`
`TO SECURITY COMPUTER FOR
`
`
`
`CALLS IN INPUT WITH
`
`352
`
`INVOKE ORIGINAL FUNCTION
`
`COMPARE CONTENT SECURITY
`
`PROFILE WITH CLIENT SECURITY
`POLICY
`
`SAFE FOR CLIENT TO INVOKE
`ORIGINAL FUNCTION WITH
`INPUT?
`YES
`
`368
`
`SET INDICATGR = FALSE
`
`TRANSMIT INDICATOR AND
`MODIFIED INPUT TO CLIENT
`COMPUTER
`
`
`FIG. 3
`
`FINJAN-JN 002028
`
`

`

`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 6 of 17
`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 6 of 17
`
`U.S. Patent
`
`Mar.20, 2012
`
`Sheet 4 of 5
`
`US 8,141,154 B2
`
`CLIENT TRANSMITTER
`
`CONTENT PROCESSOR
`
`
`
`CLIENTCOMPUTER
`
`CLIENT RECEIVER
`
`5
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`GATEWAY RECEIVER
`
`FIG.4
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`INPUT,CLIENT1D
`
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`
`
`
`GATEWAYCOMPUTER
`
`405
`
`
`
`ORIGINALINCOMING
`
`CONTENT
`
`420
`
`FINJAN-JN 002029
`
`

`

`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 7 of 17
`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 7 of 17
`
`U.S. Patent
`
`Mar.20, 2012
`
`Sheet 5 of 5
`
`US 8,141,154 B2
`
`— GATEWAY COMPUTER —
`
`j— CUENT COMPUTER —|
`
`RECEIVE CONTENT FROM
`NETWORK INTENDED FOR CLIENT
`COMPUTER
`
`+ PRESENCE OF FUNCTION CALLS
`
`SCAN CONTENTANPUT FOR
`
`
`FUNCTION GALLS FOUND?
`
`REPLACE ORIGINAL FUNCTION
`
`
`CALLS WITH SUBSTITUTE
`FUNCTION CALLS
`
`
`
`TRANSMIT CONTENT TO CENT
`RECEIVE GONTENT FROM
`
`FOR PROCESSING
`
`
`RECEIVE INPUT AND CLIENT ID
`CONTINUETO PROCESS
`
`FROM CUENT COMPUTER
`CONTENT
`
`
`
`
`SCAN INPUT TO OETERMINE
`INVOKE SUBSTITUTE FUNCTION
`
`SECURITY PROFILE
`
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`
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`GATEWAY COMPUTER
`
`
` 535)
`
`525
`
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`RETRIEVE SECURITY POLICY FOR
`CLIENT COMPUTER
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`
`
`
`TRANSMIT INPUT AND CLIENT ID
`TO GATEWAY COMPUTER FOR
`
`INSPECTION
`
`
`
`
`COMPARE CONTENT SECURITY
`
`PROFILE WITH CLIENT SECURITY
`POLICY
`
`
`
`SAFE FOR CLIENT TO INVOKE
`
`INDICATOR = TRUE?
`ORIGINAL FUNCTION WITH
`INPUT?
`
`INVOKE ORIGINAL FUNCTION
`WITH ENPUT
`
`
`RECEIVE SAFETY INDICATOR
`
`FROM GATEWAY COMPUTER
`
`
`
`SET INDICATOR = TRUE
`
`
`
`SET INDICATOR = FALSE
`
`
`
`TRANSMIT INDICATOR TO CLIENT
`COMPUTER
`
`
`FIG. 5
`
`FINJAN-JN 002030
`
`

`

`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 8 of 17
`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 8 of 17
`
`US 8,141,154 B2
`
`1
`SYSTEM AND METHOD FOR INSPECTING
`DYNAMICALLY GENERATED EXECUTABLE
`CODE
`
`
`
`FIELD OF THE INVENTION
`
`The present invention relates to computer security, and
`moreparticularly to protection against malicious code suchas
`computer viruses.
`
`BACKGROUNDOF THE INVENTION
`
`Computerviruses have been rampantfor over two decades
`now. Computer viruses generally come in the form of execut-
`able code that performs adverse operations, such as modify-
`ing a computer’s operating system orfile system, damaging a
`computer’s hardware or hardware interfaces, or automati-
`cally transmitting data from one computer to another. Gener-
`ally, computer viruses are generated by hackers willfully, in
`order to exploit computer vulnerabilities. However, viruses
`can also arise by accident due to bugs in software applica-
`tions.
`
`Originally computer viruses were transmitted as execut-
`able code inserted into files. As each new virus was discov-
`ered, a signature of the virus was collected by anti-virus
`companies and used from then on to detect the virus and
`protect computers against it. Users began routinely scanning
`their file systems using anti-virus software, which regularly
`updatedits signature database as each new virus was discov-
`ered.
`
`Such anti-virusprotection is referred to as “reactive”, since
`it can only protect in reactionto viruses that have already been
`discovered.
`
`
`
`With the advent ofthe Internet andtheabilityto run execut-
`able code such as scripts within Internet browsers, anew type
`of virus formed; namely, a virus that enters a computer over
`the Internet and not through the computer’s file system. Such
`Internet viruses can be embedded within web pages and other
`webcontent, and begin executing within an Internet browser
`as soon as they enter a computer. Routine file scans are not
`able to detect such viruses, and as a result more sophisticated
`anti-virus tools had to be developed.
`Two generic types of anti-virus applications that are cur-
`rently available to protect against such Internet viruses are (1)
`gateway security applications, and(ii) desktop security appli-
`cations. Gateway security applications shield web content
`before the content is delivered to its intended destination
`computer. Gateway security applications scan web content,
`and block the content from reaching the destination computer
`if the content is deemed by the security application to be
`potentially malicious. In distinction, desktop security appli-
`cations shield against web content after the content reachesits
`intended destination computer.
`Moreover, in addition to reactive anti-virus applications,
`that
`are based on databases of known virus signatures,
`recently “proactive” antivirus applications have been devel-
`oped. Proactive anti-virus protection uses a methodology
`knownas “behavioral analysis” to analyze computer content
`for the presence ofviruses. Behavioranalysis is used to auto-
`matically scan and parse executable content, in order to detect
`which computer operations the content may perform. As
`such, behavioral analysis can blockviruses that have not been
`previously detected and which do not have a signature on
`record, hence the name“proactive”.
`Assignee’s U.S. Pat. No. 6,092,194 entitled SYSTEM
`AND METHODFOR PROTECTING A COMPUTER AND
`A NETWORK FROM HOSTILE DOWNLOADABLES,the
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`contents of which are hereby incorporated by reference,
`describes gateway level behavioral analysis. Such behavioral
`analysis scans and parses content received at a gateway and
`generates a security profile for the content. A security profile
`is a general list or delineation of suspicious, or potentially
`malicious, operations that executable content may perform.
`The derived security profile is then compared with a security
`policy for the computer being protected,
`to determine
`whetheror not the content’s security profile violates the com-
`puter’s security policy. A security policy is a general set of
`simple or complex rules, that may be applied logically in
`series or in parallel, which determine whetheror not a specific
`operation is permitted or forbidden to be performed by the
`content on the computer being protected. Security policies are
`generally configurable, and set by an administrator of the
`computer that is being protected.
`Assignee’s U.S. Pat. No. 6,167,520 entitled SYSTEM
`AND METHODFOR PROTECTING A CLIENT DURING
`RUNTIME FROM HOSTILE DOWNLOADABLES, the
`contents of which are hereby incorporated by reference,
`describes desktop level behavioral analysis. Desktop level
`behavioral analysis is generally implemented during run-
`time, while a computer’s web browser is processing web
`content received over the Internet. As the content is being
`processed, desktop security applications monitor calls made
`to critical systems of the computer, such as the operating
`system, the file system and the network system. Desktop
`security applications use hooks to intercept calls made to
`operating system functions, and allow or block the calls as
`appropriate, based on the computer’s security policy.
`Each of the various anti-virus technologies, gateway vs.
`desktop, reactive vs. proactive, has its pros and cons. Reactive
`anti-virus protection is computationally simple and fast; pro-
`active virus protection is computationally intensive and
`slower. Reactive anti-virus protection cannot protect against
`new “first-time” viruses, and cannot protect a user if his
`signaturefile is out ofdate; proactive anti-virus protection can
`protect against new “first-time” viruses and do not require
`regular downloading of updated signature files. Gateway
`level protection keeps computer viruses at a greater distance
`froma local network ofcomputers; desktop level protection is
`more accurate. Desktop level protection is generally available
`in the consumer market for hackers to obtain, and is suscep-
`tible to reverse engineering; gateway level protection is not
`generally available to hackers.
`Reference is now made to FIG. 1, which is a simplified
`block diagram of prior art systems for blocking malicious
`content, as described hereinabove. The topmost system
`shown in FIG.1 illustrates a gateway level security applica-
`tion. The middle system shown in I'lG.1 illustrates a desktop
`level security application, and the bottom system shown in
`FIG.1 illustrates a combined gateway+desktop level security
`application.
`The topmost system shown in FIG.1 includes a gateway
`computer 105 that receives content from the Internet, the
`content intendedfor deliveryto a client computer 110. Gate-
`way computer 105 reccives the content over a communication
`channel 120, and pateway computer communicates with cli-
`ent computer 110 over a communication channel 125. Gate-
`way computer 105 includes a gateway receiver 135 and a
`gateway transmitter 140. Client computer 110 includes a
`client receiver 145. Client computer generally also has a
`client transmitter, which is not shown.
`Client computer 110 includes a content processor 170,
`suchas a conventional web browser, whichprocesses Internet
`content and renders it for interactive viewing on a display
`monitor. Such Internet content may be in the form of execut-
`
`FINJAN-JN 002031
`
`

`

`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 9 of 17
`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 9 of 17
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`US 8,141,154 B2
`
`4
`3
`tion, since the malicious JavaScript is not present in the con-
`able code, JavaScript, VBScript, Java applets, ActiveX con-
`tent prior to run-time. A content inspector will only detect the
`trols, which are supported by web browsers.
`presence ofa call to Document.write() with input text that is
`Gateway computer 105 includes a content inspector 174
`yet unknown.If such a content inspector were to blockall
`which may be reactive or proactive, or a combination of
`calls to Document.write( ) indiscriminately, then many harm-
`reactive and proactive. Incoming content is analyzed by con-
`less scripts will be blocked, since most of the time calls to
`tent inspector 174 before being transmittedto client computer
`Document.write( ) are made for dynamic display purposes
`110. If incoming content is deemed to be malicious, then
`only.
`gateway computer 105 preferably prevents the content from
`USS. Pat. Nos. 5,983,348 and 6,272,641, both to Ji, describe
`reaching client computer 110. Alternatively, gateway com-
`reactive client level content inspection, that modifies down-
`puter 105 may modily the content so as to renderit harmless,
`loaded executable code within a desktop level anti-virus
`and subsequently transmit the modified content to client com-
`application. However, such inspection can only protect
`puter 110.
`against static malicious content, and cannot protect against
`Content inspector 174 can be used to inspect incoming
`dynamically generated malicious content.
`content, on its way to client computer 110 as its destination,
`Desktop level run-time behavioral analysis has a chance of
`and also to inspect outgoing content, being sent from client
`shielding a client computer against dynamically generated
`computer 110 as its origin.
`malicious code, since such code will ultimately makeacall to
`The middle system shown in FIG. 1 includes a gateway
`an operating system function. However, desktop anti-virus
`computer 105 and a client computer 110, the client computer
`protection has a disadvantage ofbeing widely available to the
`110 including a content inspector 176. Content inspector 176
`hacker community, whichis always eager to find vulnerabili-
`may be a conventional Signature-based anti-virus applica-
`ties. In addition, desktop anti-virus protection has a disadvan-
`tion, or arun-time behavioral based application that monitors
`tage of requiring installation ofclient software.
`run-timecalls invoked by content processor 170 to operating
`As such, there is a need for a new form of behavioral
`system,file system and network system functions.
`analysis, which can shield computers from dynamically gen-
`The bottom system shownin FIG.1 includes botha content
`erated malicious code without running on the computeritself
`inspector 174 at gateway computer 105, and a content inspec-
`that is being shielded.
`tor 176 at client computer 110. Such a system can support
`conventional gateway level protection, desktop level protec-
`tion, reactive anti-virus protection and proactive anti-virus
`protection.
`Asthe hacker vs. anti-virus protection battle continues to
`wage, a newer lype of virus has sprung forward; namely,
`dynamically generated viruses. These viruses are themselves
`generated only at run-time, thus thwarting conventional reac-
`tive analysis and conventional gateway level proactive behav-
`ioral analysis. These viruses take advantage of features of
`dynamic HTML generation, such as executable code or
`scripts that are embedded within HTML pages, to generate
`themselves onthe fly at runtime.
`For example, consider the following portion of a standard
`HTMLpage:
`
`20
`
`30
`
`40
`
`SUMMARY OF THE DESCRIPTION
`
`The present invention concerns systems and methods for
`implementing new behavioral analysis technology. The new
`behavioral analysis technology affords protection against
`dynamically generated malicious code,in addition to conven-
`tional computer virusesthat are statically generated.
`The present invention operates through a security com-
`puter that is preferably remote from a client computerthat is
`being shielded while processing network content. During
`run-time, while processing the network content, but before
`the client computer invokes a function call that may poten-
`tially dynamically generate malicious code, the client com-
`puter passes the input to the function to the security computer
`for inspection, and suspends processing the network content
`pending a reply back from the security computer. Since the
`inputto the functionis being passed at run-time,it has already
`been dynamically generated andis thus readily inspected by
`a contentinspector. Referring to the example above, were the
`input to be passed to the security computerprior to run-time,
`it would take the form of indeterminate text; whereas the
`input passed during run-time takes the determinate form
`<SCRIPT>malicious JavaScript</SCRIPT>,
`which can readily be inspected. Upon receipt ofa reply from
`the security computer, the client computer resumes process-
`ing the network content, and knows whether to by-pass the
`function call invocation.
`To enable the client computerto pass function inputs to the
`security computer and suspendprocessing ofcontent pending
`replics from the security computer, the present invention
`operates by replacing original function calls with substitute
`function calls within the content, at a gateway computer, prior
`to the content being received at the client computer.
`The present invention also provides protection against
`arbitrarily many recursive levels of dynamic generation of
`malicious code, whereby such code is generated via a series
`of successive function calls, one within the next.
`By operating through the mediumofa security computer,
`the present invention overcomesthe disadvantages ofdesktop
`anti-virus applications, which are available to the hacker
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`FINJAN-JN 002032
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`<!DOCTYPE HTML PUBLIC *-//W3C//DTD HTML4.0
`Transitional//EN”>
`<HTML>
`<SCRIPT LANGUAGE="JavaScript”>
`document.write(“<h1>text that is generated at run-time</h1>"");
`</SCRIPT>
`<BODY>
`</BODY>
`</HTML>
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`The text within the <SCRIPT> tags is JavaScript, and
`includes a call to the standard function document.write( ),
`which generates dynamic HTMI.. In the example above, the :
`function document.write( ) is used to generate HTML header
`text, with a text string that is generated at run-time. If the text
`string generated at run-time is of the form
`<SCRIPT>malicious JavaScript</SCRIPT>
`then the document.write( ) function will insert malicious
`JavaScript into the HTMLpagethat is currently being ren-
`dered by a web browser. In turn, when the web browser
`processes the inserted text, it will perform malicious opera-
`tions to the client computer.
`Such dynamically generated malicious code cannot be
`detected by conventionalreactive content inspection and con-
`ventional gateway level behavioral analysis content inspec-
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`US 8,141,154 B2
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`community for exploit. Security applications embodying the
`present invention are concealed securely within managed
`computers.
`There is thus provided in accordance with a preferred
`embodimentofthe present invention a methodfor protecting
`aclient computer from dynamically generated malicious con-
`tent, including receiving at a gateway computer content being
`sent to a client computer for processing,the content including
`a call to an original function, and the call including an input,
`modifying the content at the gateway computer, including
`replacing the call to the original function with a correspond-
`ing call to a substitute function, the substitute function being
`operational to send the input to a security computer for
`inspection, transmitting the modified content from the gate-
`way computer to the client computer, processing the modified
`content at the client computer, transmitting the input to the
`security computer for inspection whenthe substitute function
`is invoked, determiningat the security computer whetherit is
`safe for the client computer to invoke the original function
`with the input, transmitting an indicator of whetherit is safe
`for the client computer to invoke the original function withthe
`input, from the security computerto the client computer, and
`invoking the original function at the client computer with the
`input, only if the indicator received from the security com-
`puter indicates that such invocationis safe.
`There is further provided in accordance with a preferred
`embodimentof the present invention a system for protecting
`aclient computer from dynamically generated malicious con-
`tent,
`including a gateway computer, including a gateway
`receiver for receiving content being sent to a client computer
`for processing, the content including a call to an original
`function, and the call including an input, a content modifier
`for modifying the received content byreplacing the call to the
`original function with a corresponding call to a substitute
`function, the substitute function being operational to send the
`input to a security computer for inspection, and a galeway
`transmitter for transmitting the modified content from the
`gateway computer to the client computer, a security com-
`puter, including a security receiver for receiving the input
`from the client computer, an input inspector for determining
`whetherit is safe for the client computerto invoke the original
`function with the input, and a security transmitter for trans-
`mitting an indicator ofthe determiningto the client computer,
`and a client computer communicating with the gateway com-
`puter and with the security computer,
`including a client
`receiver for receiving the modified content from the gateway
`computer, and for receiving the indicator from the security
`computer, a content processor for processing the modified
`content, and for invoking the original function only if the
`indicator indicates that such invocation is safe; and a client
`transmitter for transmitting the input to the security computer
`for inspection, when the substitute function is invoked.
`There is yet further provided in accordance with a preferred
`embodiment of the present invention a computer-readable
`storage medium storing program codefor causing at least one:
`computing device to receive content including a call to an
`original function, and thecall including an input, replace the
`call to the original function with a corresponding call to a
`substitute function, the substitute function being operational
`to send the input for inspection, thereby generating modified
`content, process the modified content, transmit the input for
`inspection, when the substitute function is invoked while
`processing the modified content, and suspend processing of
`the modified content, determine whetherit is safe to invoke
`the original function with the input, transmit an indicator of
`whetherit is safe for a computer to invoke the original func-
`tion with the input, and resume processing of the modified
`
`6
`content after receiving the indicator, and invoke the original
`function with the input only ifthe indicator indicates that such
`invocationis safe.
`There is additionally provided in accordance with a pre-
`ferred embodiment of the present invention a method for
`protecting a client computer from dynamically generated
`malicious content, including receiving content being sent toa
`client computer for processing, the content including a call to
`an original function, and the call including an input, modify-
`ing the content, including replacing the call to the original
`function with a correspondingcall to a substitute function, the
`substitute function being operational to send the input to a
`security computer for inspection, and transmitting the modi-
`fied content to the client computer for processing.
`There is moreover provided in accordance with a preferred
`embodimentofthe present invention a system for protecting
`aclient computer from dynamically generated malicious con-
`tent, including a receiver for receiving content being sent to a
`client computer for processing, the content including a call to
`an original function, andthe call including an input, a content
`modifier for modifying the received content by replacing the
`call to the original function with a corresponding call to a
`substitute function, the substitute function being operational
`to send the input to a security computer for inspection, and a
`transmitter for transmitting the modified contentto the client
`computer.
`There is further provided in accordance with a preferred
`embodiment of the present invention a computer-readable
`storage medium storing program code for causing a comput-
`ing device to receive content including a call to an original
`function, and thecall including an input, and replace the call
`to the original function with a correspondingcall to a substi-
`tute function, the substitute function being operational to send
`the input for inspection.
`There is yet further provided in accordance with a preferred
`embodimentof the present invention a method for protecting
`aclient computer from dynamically generated malicious con-
`tent, including receiving content being sent to a client com-
`puter for processing, the content including a call to an original
`function, and the call including an input, modifying the con-
`tent, including replacing thecall to the original function with
`a corresponding call to a substitute function, the substitute
`function being operational to send the input for inspection,
`transmitting the modified content to the client computer for
`processing, receiving the input from the client computer,
`determining whether it is safe for the client computer to
`invokethe original function with the input, and transmitting
`to the client computeran indicator of whetherit is safe for the
`client computerto invoke the original function with the input.
`There is additionally provided in accordance with a pre-
`ferred embodiment of the present invention a system for
`protecting a client computer from dynamically generated
`malicious content, including a receiver(i) for receiving con-
`tent being sent toa client computerfor processing, the content
`including a call to an original function, and the call including
`an input, and (ii) for receiving the input from the client com-
`puter, a content modificr for modifying the received content
`by replacing the call to the original function with a corre-
`sponding call to a substitute function, the substitute function
`being operational to send the input for inspection, an input
`inspector for determining whether it is safe for the client
`computer to invoke the original function with the input, and a
`transmitter (1) for transmitting the modified content to the
`client computer, and (11) for transmitting an indicator of the
`determining to the client computer.
`There is moreover provided in accordance with a preferred
`embodiment of the present invention a computer-readable
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`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 11 of 17
`Case 3:17-cv-05659-WHA Document 111-2 Filed 06/15/18 Page 11 of 17
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`US 8,141,154 B2
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`7
`storage mediumstoring program code for causing a comput-
`ing device to receive content including a call to an original
`function, and the call including an input, replace the call to the
`original function with a corresponding call to a substitute
`function, the substitute function being operational to send the
`input for inspection, and determine whetherit is safe for a
`computer to invoke the original function with the input.
`There is further provided in accordance with a preferred
`embodimentofthe present invention a methodfor protecting
`a computer from dynamically generated malicious content,
`including processing content received over a network, the
`contentincludinga call to a first function, and the call includ-
`ing an input, transmitting the input to a security computer for
`inspection, whenthefirst function is invoked, receiving from
`the security computer an indicator of whetherit is safe to
`invoke a second function with the input, and invoking the
`second function with the input, only if the indicator indicates
`that such invocationis safe.
`
`There is yet further provided in accordance with a preferred
`embodimentof the present invention a systemfor protecting
`a computer from dynamically generated malicious content,
`including a content processor (1) for processing content
`received over a network, the content including a call to a first
`function, and the call including an input, and (ii) for invoking
`a second function with the input, only if a security computer
`indicates that such invocationis safe, a transmitter for trans-
`mitting the input to the security computer for inspection,
`whenthefirst function is invoked, and a receiver for receiving
`an indicator from the security computer whether it is safe to
`invoke the second function with the input.
`There is a