Step-by-Step Tutorial: Analyzing Code Differences with HexCmp
When working with binary files, executable code, or compiled firmware, standard text-based comparison tools are useless. You need a dedicated binary comparison tool. HexCmp is a powerful utility that combines a hex editor and a file comparison engine. This tutorial will guide you through analyzing code differences using HexCmp. Prerequisites Before starting, ensure you have the following: A installed copy of HexCmp.
Two binary files to compare (e.g., two versions of a compiled program or a modified firmware file). Step 1: Load Your Files Launch HexCmp to see two empty parallel panels. Click File in the top menu. Select Open First… and choose your original binary file.
Click File again, select Open Second…, and choose your modified binary file.
Both files will load side-by-side in hex format with their ASCII representations on the right. Step 2: Configure the Comparison Settings
Before running the analysis, adjust your viewing preferences for better visibility. Go to Options > Settings.
Choose your Color Schema to highlight differences clearly (e.g., bright red for mismatches).
Set the Synchronous Scrolling option to “On” so both files move together. Step 3: Run the Comparison
HexCmp automatically analyzes files upon loading, but you can manually control the navigation.
Press F4 to find the very first difference between the files.
The software will instantly highlight the mismatched bytes in both panels.
Look at the bottom status bar to see the exact memory offset address of the difference. Step 4: Navigate and Interpret Differences
Analyzing code requires understanding what the changes mean.
Modified Bytes: If the byte length matches but values differ, a value or instruction was changed.
Missing/Inserted Bytes: If the hex addresses shift out of alignment, code was added or deleted.
Next Difference: Press F4 to jump forward to the next modification. Previous Difference: Press Shift + F4 to step backward. Step 5: Edit and Align Code (Optional)
If you are debugging or patching, you can edit code directly inside HexCmp.
Click directly on the byte you want to change in either panel. Type the new hex values.
If you need to realign shifted code, use the Insert Channels feature to push bytes down and restore parallel alignment. Go to File > Save to commit your patches. Step 6: Export the Results For documentation or version control, export your findings. Navigate to File > Generate Report. Select your desired format (Text or HTML).
Save the log, which maps out every single changed address and its before-and-after values. To help me tailor this guide, please let me know:
What type of files are you analyzing (e.g., malware samples, firmware, game ROMs)?
Are you looking to patch the code or just observe differences?
Do you need help interpreting specific hex values or assembly instructions? AI responses may include mistakes. Learn more
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