Foiling a document exploit attack

1. A computer-controlled method, comprising:

using a processor and a computer-readable memory storing computer program code that when executed, foils a document exploit attack that attempts to extract malware code from within a document stored on the compute, by

monitoring the computer in order to detect repeated function calls made by a given process in respect of the same function but different file descriptors; and

in the event that such repeated function calls are detected or the number of such repeated function calls exceeds some threshold, terminating the process that initiated the function calls.

2. A method as claimed in claim 1 , wherein the step of monitoring the computer comprises hooking the function calls at the computer.

3. A method as claimed in claim 1 , wherein the computer is monitored to detect repeated function calls where the file descriptors are values that increment or decrement in sequence.

4. A method as claimed in claim 1 , wherein the repeated function calls to be detected are failed function calls.

5. A method as claimed in claim 1 , wherein the computer is running a Microsoft® Windows® operating system and said function calls are GetFileSize function calls.

6. A method as claimed in claim 1 , wherein the computer is running a Linux® operating system and said function calls are fstat function calls.

7. A method as claimed in claim 1 , wherein the method further comprises quarantining or deleting the document containing the exploit after the process has been terminated.

8. A non-transitory computer readable medium storing a computer program which, when run on a computer, causes the computer to:

use a processor and a computer-readable memory storing computer program code that when executed, foils a document exploit attack that attempts to extract malware code from within a document stored on the computer, by

monitoring itself in order to detect repeated function calls made by a given process in respect of the same function but different file descriptors; and

in the event that such repeated function calls are detected or the number of such repeated function calls exceeds some threshold, terminating the process that initiated the function calls.

9. A computer program product comprising a non-transitory computer-readable storage medium bearing computer program code for use with a computer, the computer program code comprising:

code for monitoring the computer in order to detect repeated function calls made by a given process in respect of the same function but different file descriptors; and

code for terminating the process that initiated the function calls in the event that such repeated function calls are detected or the number of such repeated function calls exceeds some threshold;

wherein a processor and a computer-readable memory storing the computer program code are used such that when the computer program code is executed, a document exploit attack that attempts to extract malware code from within a document stored on the computer is foiled.

10. A computer system comprising:

one or more processors; and

one or more computer-readable memories storing computer program code,

the one or more processors being configured to execute the computer program code to cause the computer system at least to:

use the processor and the computer-readable memory storing computer program code such that when executed, a document exploit attack that attempts to extract malware code from within a document stored on the computer is foiled, by

monitoring itself in order to detect repeated function calls made by a given process in respect of the same function but different file descriptors; and

in the event that such repeated function calls are detected or the number of such repeated function calls exceeds some threshold, terminating the process that initiated the function calls.

11. A computer system as claimed in claim 10 , wherein the repeated function calls to be detected have file descriptor values that increment or decrement in sequence.

12. A computer system as claimed in claim 10 , wherein the repeated function calls to be detected are failed function calls.

13. A computer system as claimed in claim 10 , wherein the computer system is running a Microsoft® Windows® operating system and said function calls are GetFileSize function calls.

14. A computer system as claimed in claim 10 , wherein the computer system is running a Linux® operating system and said function calls are fstat function calls.

15. A computer system as claimed in claim 10 , wherein the one or more processors are configured to execute the computer program code to further cause the computer system to quarantine or delete the document containing the exploit after the process has been terminated.