Saturday, May 11, 2013

MS12-076 Excel SerAuxErrBar Heap Overflow Vulnerability

There was a Heap Overflow vulnerability (CVE-2012-1885) in Excel while parsing SerAuxErrBar structure from xls (Excel's old binary format) files. So I decided to took on it (a little bit analysis). But I faced with reality that there is no public debugging symbols for Excel :( When I read advisory [1] I don't understand anything as always 'cause Microsoft only says "A remote code execution vulnerability exists in the way that Microsoft Excel handles specially crafted Excel files. An attacker who successfully exploited this vulnerability could take..". That's shit description :( Then I look for SerAuxErrBar structure and found something on MSDN that describes this structure [2]. But there was another question. "How one could create SerAuxErrBar structure?".

Thursday, April 11, 2013

Metasploit Framework ile Exploit Gelistirme Sunumu

Uzun bir sure sonra blog yaziyorum sanirim:) Gecenlerde Fatih Ozavci ile Ozgur Yazilim Gunleri 2013'te Metasploit Framework ile Exploit Gelistirme baslikli bir sunum gerceklestirdik. Metasploit Framework yapisi, exploiting (cok yuzeysel) ve ornek moduller uzerinden modul gelistirme konusunda bilgi aktarmaya calistik. Merak edenler icin sunum asagida.

 Ayrica umuyorum tekrar bir seyler yazarim buraya yakin zamanda.


Sunday, September 2, 2012

WebKit cssText NULL Ptr Deref

Just tested with Chrome 21.0.1180.89 m (latest version)

Crash moment:
0:000> r
eax=00000000 ebx=015ccfb0 ecx=00000000 edx=0014ea24 esi=01e00440 edi=01e44630
eip=58fcd2a8 esp=0014e8b0 ebp=0014e8b4 iopl=0         nv up ei pl nz na po nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00010202
58fcd2a8 8b4804          mov     ecx,dword ptr [eax+4] ds:002b:00000004=????????


Same bug in old release (19.0.1084.52)

Tuesday, August 28, 2012

CVE-2012-2760 Session Stealing in mod_auth_openid

As advisory describing, mod_auth_openid is vulnerable to session stealing. Because "Session ids are stored insecurely in /tmp/mod_auth_openid.db (default filename). The db is world readable and the session ids are stored unencrypted." [1]

Yes, this is important issue and file is accessible by local attackers. But more important issue is database file also accessible by remote attackers in some cases (For example, if application have some kind of arbitrary file download/access vulnerability like LFI) because file is located in tmp folder (apache can access tmp directory) and sqlite db is not encrypted.

SQLite is not supporting database file encryption but there are some external libraries that "provides transparent 256-bit AES encryption of database files". [2]

Dear mod_auth_openid developers, you should use database file encryption. :(


Wednesday, August 15, 2012

Uniform Binary Search Implementation in JavaScript

Uniform binary search is an optimization of the classic binary search algorithm invented by Donald Knuth and given in Knuth's The Art of Computer Programming. It uses a lookup table to update a single array index, rather than taking the midpoint of an upper and a lower bound on each iteration; therefore, it is optimized for architectures (such as Knuth's MIX) on which
  • a table lookup is generally faster than an addition and a shift, and 
  • many searches will be performed on the same array, or on several arrays of the same length

Just simply implemented in JS from original C source of Knuth's algorithm.

// target = [91, 97, 99, 101, 127, 129, 145]
// will found index of 127 via optimized bin search algo.

middle of target: 3
127 is bigger than 101
127 is less than 129
127 at index: 4