Fancy Return Address

Author: David Zimmer
Date: 08.17.10 - 5:31am

So a while back I am working on determining if I can get controlled memory execution for a memory corruption issue. There is an off by one in a sub function that is overwriting stack memory one byte at a time each time the sub function is called from the parent. The sub function also makes use of a function pointer which as it turns out is one of the first things you start to control as memory gets corrupted.

This makes for an interesting exploit development cycle because the function pointer you are controlling is activley in use and you can only control 1 byte at a time. This means you have to potentially come up 3 valid return addresses, within a limited predefined range and get it to return back to the original function without crashing so the next byte overwrite can occur on schedule.

(The first byte a return address has to be within 0xFF bytes of the default pointer, second within 0xFFFF etc.)

Turned out a usable address combination did exist to pull off code execution for this particular version of the application, but talk about pulling teeth!

Anyway..something reminded me of that today and it was an interesting case so figured i would share.

Comments: (0)

Leave Comment:
Email: (not shown)
Message: (Required)
Math Question: 89 + 60 = ? followed by the letter: G 

About Me
More Blogs
Main Site
Yara WorkBench
vbdec dbg updates
vb6 PCode NOP
vb6 API and call backs
how pcode works Pt1
Reversing PCode Args
VB6 PCode Disassembly
VB6 PCode Debugger
UConnect Disable Cell Modem
IDA python over IPC
dns wildcard blocking
64bit IDA Plugins
anterior lines
misc news/updates
Decoders again
CDO.Message Breakpoints
SysAnalyzer Updates
SysAnalyzer and Site Updates
crazy decoder
ida js w/dbg
flash patching #2
JS Graphing
packet reassembly
Delphi IDA Plugin
scdbg IDA integration
API Hash Database
Winmerge plugin
IDACompare Updates
Guest Post @ hexblog
TCP Stream Reassembly
SysAnalyzer Updates
Apilogger Video
Shellcode2Exe trainer
scdbg updates
IDA Javascript w/IDE
Rop Analysis II
scdbg vrs ROP
flash patching
x64 Hooks
micro hook
jmp api+5 *2
SysAnalyzer Updates
InjDll runtime config
C# Asm/Dsm Library
Shellcode Hook Detection
Updates II
Java Hacking
Windows 8
Win7 x64
Graphing ideas
.Net Hacking
Old iDefense Releases
hll shellcode
ActionScript Tips
-patch fu
scdbg ordinal lookup
scdbg -api mode
Peb Module Lists
scdbg vrs Process Injection
GetProcAddress Scanner
scdbg fopen mode
scdbg findsc mode
scdbg MemMonitor
demo shellcodes
scdbg download
api hashs redux
Api hash gen
Retro XSS Chat Codes
Exe as DLL
Olly Plugins
Debugging Explorer
Attach to hidden process
JS Refactoring
Asm and Shellcode in CSharp
Fancy Return Address
PDF Stream Dumper
Malcode Call API by Hash
WinDbg Cheat Sheet
GPG Automation