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Problems with syscall filtering technologies on Linux



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-filtering.html

Cheers
Chris