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Immunity Debugger Buffer Overflow

By NCC Group Publication Archive

05 August 2015

Summary – 22.03.2011

Name: Immunity Debugger Buffer Overflow
Release Date: 22 March 2011
Reference: NGS00016
Discoverer: Paul Harrington
Vendor: Immunity Inc
Vendor Reference: Support #3171
Systems Affected: Windows
Risk: Low
Status: Fixed

TimeLine

Discovered: 28 October 2010
Released: 28 October 2010
Approved: 28 October 2010
Reported: 28 October 2010
Fixed:  6 December 2010
Published: 22 March 2011

Description

Immunity Debugger V1.73 contains a  buffer overflow vulnerability in its HTTP update mechanism

Technical Details

It is possible to spoof communications between the Immunity Debugger and its update servers at immunityinc.com.
By sending a specially crafted large HTTP reply it is possible to cause the Immunity Debugger to trigger the buffer overflow:

00487161  EB 02           JMP SHORT Immunity.00487165
00487163  8BD8            MOV EBX,EAX
00487165  8B83 2C060000   MOV EAX,DWORD PTR DS:[EBX+62C]    <— crash occurs here, EBX = 0x42424242
0048716B  85C0            TEST EAX,EAX

Care should be taken if using the Immunity Debugger as your JIT debugger not to get into a crash/debug/crash loop!
Various CPU Registers are overwritten, which could potentially result in remote code execution.

Fix Information