Problems with syscall filtering technologies on Linux

2009.02.01
Credit: Chris Evans
Risk: High
Local: Yes
Remote: No
CWE: CWE-264

Hi, There's a trick which may permit the bypassing of policies in technologies which do syscall filtering on the Linux x86_64 kernel. The trick is made possible by the fact that the 32-bit and 64-bit kernel tables are different, combined with the fact that a 64-bit process can make a 32-bit syscall and visa versa. The syscall "number" check can get confused and permit a syscall it did not intend to. Advisory: http://scary.beasts.org/security/CESA-2009-001.html Blog post: http://scarybeastsecurity.blogspot.com/2009/01/bypassing-syscall-filteri ng.html Cheers Chris

References:

http://www.securityfocus.com/bid/33417
http://www.securityfocus.com/archive/1/archive/1/500377/100/0/threaded
http://www.citi.umich.edu/u/provos/systrace/
http://scarybeastsecurity.blogspot.com/2009/01/bypassing-syscall-filtering.html
http://scary.beasts.org/security/CESA-2009-001.html


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