mandiant / mandiant/capa-rules
rule idea: zlib fast inflate
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- Avg merge
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- Merged PRs (30d)
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Description
see source: https://github.com/madler/zlib/blob/master/contrib/masmx86/inffas32.asm
I've seen this code used in shellcode; we can hit on the hard-coded strings or the assembly itself.
strings:
- `Fast decoding Code from Chris Anderson`
- `invalid literal/length code`
- `invalid distance code`
- `invalid distance too far back`
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reading contrib/masmx86/inffas32.asm from the linked zlib source and compare its assembly and listed strings with existing capa rules. Done means adding a rule for the zlib fast-inflate implementation and validating that it matches the intended code without relying only on incidental strings.
Written by the indexing model from the issue text.
Assessment
- Domain
- reverse-engineering, security
- Issue type
- Feature
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100