Winmerge plugin

Author: David Zimmer
Date: 01.24.14 - 6:18am

I got thinking a little more about using the winmerge plugin for disasm diffing again last night and had a few simple ideas that panned out really well.

So I was aggressively cutting the asm down to just the base instruction, order, and any new lines from where labels were. With an extra 5 minutes of coding I was able to get the match with a less aggressive filter. The full logic is:
If InStr(tmp(i), "[") > 0 Then baseCmd = baseCmd & "[]"
If InStr(tmp(i), "+") > 0 Then baseCmd = baseCmd & "+"
If InStr(tmp(i), "-") > 0 Then baseCmd = baseCmd & "-"
If InStr(tmp(i), "*") > 0 Then baseCmd = baseCmd & "*"
If ExtractConstant(tmp(i), x) Then baseCmd = baseCmd & x
Ridiculously simple, but leaves enough information in for diffutils to work much better. I also added in a slightly more complex parser as well that standardizes the asm back closer to the generic assembler mnemonics for the instructions (eg reg32, reg16 etc). Both are included in the latest build. It is interesting to test how simple is sufficient. (anyone can make a complex system, elegance is in simplicity)

I also had another idea. I wanted two more things out of my Winmerge plugin. I wanted it to be able to house multiple filters, configurable externally, and I wanted it to contain a debug interface where you could watch the data transformations and edit them manually if need be.

Both of these were also really easily added. The filter selection is based on a registry key setting set in IDACompare, and for the debug UI, All i had to do is show a form modally which pauses WinMerge and displays the data letting the user view/edit the data in real time.

When they hit continue, it goes back and WinMerge continues. Super slick.

I love that WinMerge used COM for its plugins. Below is a screen shot of the debug UI showing the signature based standardization.

(click for larger image)

The resulting diff below shows the same problem section from the last post now showing the correct results.

(click for larger image)

Sometimes its amazing what 5 minutes of coding can do :)

Comments: (1)

On 01.27.14 - 12:36am Dave wrote:
Even there there is no way to automatically configure WinMerge to apply the prediffer automatically, It turned out to be pretty easy to do it externally.
AppActivate "WinMerge - [a.idacompare - b.idacompare]"
SendKeys "%p"       //send alt-p to select plugin menu
SendKeys "{DOWN 4}" //down arrow 4x
SendKeys "{RIGHT}"  //right arrow 1x
SendKeys "{DOWN 2}" //down arrow 2x
SendKeys vbCr       //enter

Leave Comment:
Email: (not shown)
Message: (Required)
Math Question: 84 + 26 = ? followed by the letter: P 

About Me
More Blogs
Main Site
Posts: (year)
2024 (1)
     vbdec backstory
2023 (4)
     Yara Workbench Automation
     VS linker versions
     IDA decompiler comments
2022 (5)
     VB6 Implements
     VB6 Stubs BS
     VB6 TypeInfo
     VB6 VTable Layout
     Yara isPCode rule
2021 (2)
     VB6 Gosub
2020 (5)
     AutoIT versions
     IDA JScript 2
     Using VB6 Obj files from C
     Yara Corrupt Imports
     Yara Undefined values
2019 (6)
     Yara WorkBench
     vb6 API and call backs
     UConnect Disable Cell Modem
2017 (5)
     IDA python over IPC
     dns wildcard blocking
     64bit IDA Plugins
     anterior lines
     misc news/updates
2016 (4)
     KANAL Mod
     Decoders again
     CDO.Message Breakpoints
     SysAnalyzer Updates
2015 (5)
     SysAnalyzer and Site Updates
     crazy decoder
     ida js w/dbg
     flash patching #2
     JS Graphing
2014 (5)
     Delphi IDA Plugin
     scdbg IDA integration
     API Hash Database
     Winmerge plugin
     IDACompare Updates
2013 (9)
     Guest Post @ hexblog
     TCP Stream Reassembly
     SysAnalyzer Updates
     Apilogger Video
     Shellcode2Exe trainer
     scdbg updates
     IDA Javascript w/IDE
     Rop Analysis II
     scdbg vrs ROP
2012 (13)
     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
2011 (19)
     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
2010 (11)
     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
2009 (1)
     GPG Automation