Posts Tagged ‘buffer overflow’

Exploiting Internet Explorer 7 – Case Study

4th August 2010

In this post we are going to take a vulnerability in Internet Explorer 6/7 that was exploited in a relatively stable manner and attempt to add the DEP bypassing ability. The main exploit for this vulnerability has been implemented as a metasploit module (“ms10_018_ie_behaviors” by moshe ben abu from rec-sec). It works well on the target platforms but it doesn’t bypass DEP (yet..).


Exploiting Internet Explorer 7 With Dot Net

4th August 2010

In this post we will demonstrate the method discussed by mark dowd and alex sotirov for bypassing DEP and ASLR on IE 6/7 running on a windows vista machine. This method is simple and useful. We will create a .NET ActiveX that will be loaded by IE. The ActiveX will be loaded into a fixed address and will be executable. To overcome the difficulties we need two things

  • To make the ActiveX load into a constant address by removing the IMAGE_DLL_CHARACTERISTICS_DYNAMIC_BASE
  • Select the image base we want.

The flag IMAGE_DLL_CHARACTERISTICS_DYNAMIC_BASE means that the ActiveX can be loaded at a dynamic address. Removing this flag will indicate that it can’t, and help solve the ASLR problem on IE. Once we bypassed ASLR we can select the image base we want. This way when we gain control over EIP we can jump directly to our shellcode.


OSX ROP Exploit – EvoCam Case Study

6th July 2010


OSX ROP exploit

This post follows on from my previous OS X exploit tutorial which demonstrated finding a buffer overflow in an OS X application and developing a working exploit for it. The technique used in that tutorial only worked on the previous incarnation of Apple’s OS X operating system known as Leopard (10.5.x).

I stupidly mentioned at the end of my previous post that future OS X exploit would likely rely on ROP based techniques in order to bypass non-executable memory protection and achieve code execution. I was then challenged by then Offensive Security team to produce a follow up post, so the obvious next port of call was to get my previous EvoCam exploit working on Snow Leopard.


Analyzing undocumented formats

28th June 2010

Exploit DatabaseUsually when I analyze a protocol or a file-format I spend a few hours or days mapping out targets. The first step towards really understanding what you’re dealing with is to really get to know your target.

  • Search for old vulnerabilities, find a common motive.
  • Attempt to find signatures of third party libraries. If found, check if they are indeed the last version
  • Map out the types of data that the application parses. (for example, on internet explorer you could attempt to attack jpg images, the java-script interpreter, and many other components that are being parsed by internet explorer or passed on to the operating system)