mandiant / mandiant/capa-rules

suggested rule improvements

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Description

btw, here's is a loose collection of things that bumped my while converting the rules to yara. none of them is really bad but they could be improved:

* lots of regexes contain .* which yara complains about because it slows down the search. had to convert them to {,1000}
* capa accepts "string: /com/exe4j/runtime/exe4jcontroller/i" without escaping the inner slashes
* there were several regexes like e.g. string: /A09E667F3BCC908B/i which could be perfectly done with string search but there's no way to ignore casing on strings.

_Originally posted by @ruppde in https://github.com/fireeye/capa-rules/issues/384#issuecomment-842685775_

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Review the three concerns described in the issue: unbounded regex patterns, unescaped inner slashes, and case-insensitive literal strings. First determine which capa rule files and YARA conversion behavior are involved; done would require a specific, agreed scope and validation that the affected rules remain equivalent and performant.

Written by the indexing model from the issue text.

Assessment

Domain
reverse-engineering
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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