Exploit writing tutorial part 11 : Heap Spraying Demystified

A lot has been said and written already about heap spraying, but most of the existing documentation and whitepapers focus on IE7 or older versions.
Although there are a number of public exploits available that target IE8, the exact technique to do so has not been really documented in detail.
Of course, you can probably derive how it works by looking at those public exploits.

With this tutorial, I’m going to provide you with a full and detailed overview on what heap spraying is, and how to use it on old and newer platforms.
I’ll start with some “ancient” techniques (or classic techniques if you will) that can be used on IE6 and IE7.
We’ll also look at heap spraying for non-browser applications.
Next, we’ll talk about precision heap spraying, which is a requirement to make DEP bypass exploits work on IE8.
I’ll finish this tutorial with sharing some of my own research on getting reliable heap spraying to work on IE9.
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WoW64 Egghunter

Traditional Egghunter An Egghunter is nothing more than an assembly routine to find shellcode somewhere in memory. We typically deploy an Egghunter when there is no more room in our buffer that we can use to initially redirect EIP to. If we are able to load our shellcode elsewhere in process memory, the Egghunter will […]

Metasploit Bounty – the Good, the Bad and the Ugly

On June 14, 2011 HD Moore announced the Metasploit Bounty contest, offering a cash incentive for specific vulnerabilities to be submitted as modules in the Metasploit Framework. Titled “30 exploits, $5000 in 5 weeks”, a post on the Rapid7 blog lists the 30 “bounties” selected by the MSF team, waiting for someone to claim and submit a working exploit module.
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Universal DEP/ASLR bypass with msvcr71.dll and

Over the last few weeks, there has been some commotion about a universal DEP/ASLR bypass routine using ROP gadgets from msvcr71.dll (written by Immunity Inc) and the fact that it might have been copied into an exploit submitted to Metasploit as part of the Metasploit bounty.

I’m not going to make any statements about this, but the ROP routine itself looks pretty slick.
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Exploit writing tutorial part 10 : Chaining DEP with ROP – the Rubik’s[TM] Cube

About 3 months after finishing my previous exploit writing related tutorial, I finally found some time and fresh energy to start writing a new article.
In the previous tutorials, I have explained the basics of stack based overflows and how they can lead to arbitrary code execution. I discussed direct RET overflows, SEH based exploits, Unicode and other character restrictions, the use of debugger plugins to speed up exploit development, how to bypass common memory protection mechanisms and how to write your own shellcode.
While the first tutorials were really written to learn the basics about exploit development, starting from scratch (targeting people without any knowledge about exploit development) you have most likely discovered that the more recent tutorials continue to build on those basics and require solid knowledge of asm, creative thinking, and some experience with exploit writing in general.
Today’s tutorial is no different. I will continue to build upon everything we have seen and learned in the previous tutorials. Today I will talk about ROP and how it can be used to bypass DEP (and ASLR)…
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Exploit writing tutorial part 6 : Bypassing Stack Cookies, SafeSeh, SEHOP, HW DEP and ASLR

Introduction In all previous tutorials in this Exploit writing tutorial series, we have looked at building exploits that would work on Windows XP / 2003 server. The success of all of these exploits (whether they are based on direct ret overwrite or exception handler structure overwrites) are based on the fact that a reliable return […]

Exploit writing tutorial part 3 : SEH Based Exploits

In the first 2 parts of the exploit writing tutorial series, I have discussed how a classic stack buffer overflow works and how you can build a reliable exploit by using various techniques to jump to the shellcode.  The example we have used allowed us to directly overwrite EIP and we had a pretty large […]

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