patch-diff-analyzer

Binary patch analysis identifies security-relevant changes by decompiling unpatched and patched binaries, then generating diffs to reveal what was modified. This Skill automates the comparison workflow using jadx, jd-cli, CFR, or ilspycmd to expose source code or IL from Java JARs and .NET DLLs, producing patch-analysis.diff and changed-files.txt for vulnerability analysis.

The Skill integrates jadx, jd-cli, and CFR for Java JAR decompilation, and ilspycmd for .NET DLLs and EXEs. It applies the appropriate decompiler based on binary type, then generates diffs between decompiled versions to expose security changes across commits or releases.

Yes. The Skill handles Java JARs via jadx, jd-cli, or CFR, and .NET DLLs/EXEs via ilspycmd. Set up separate git workflows per binary type, tag unpatched and patched versions, and run analyze-diff.sh to generate patch reports for both platforms.

Create a workspace, decompile the unpatched binary into decompiled/, commit and tag as 'unpatched', then decompile the patched binary, commit and tag as 'patched'. Running analyze-diff.sh generates patch-analysis.diff and changed-files.txt showing all security-relevant modifications between versions.

The Skill generates patch-analysis.diff, which shows line-by-line differences between decompiled versions, and changed-files.txt, which lists all modified files. These outputs enable rapid identification and documentation of security changes for vulnerability assessment.

Git is required. The Skill uses git tags ('unpatched' and 'patched') to organize decompiled source versions and generate diffs. The git-based workflow ensures repeatable, version-controlled binary analysis for security patch comparison.