capa/doc/usage.md

capa usage

See capa -h for all supported arguments and usage examples.

tips and tricks

only run selected rules

Use the -t option to run rules with the given metadata value (see the rule fields rule.meta.*). For example, capa -t william.ballenthin@mandiant.com runs rules that reference Willi's email address (probably as the author), or capa -t communication runs rules with the namespace communication.

only analyze selected functions

Use the --restrict-to-functions option to extract capabilities from only a selected set of functions. This is useful for analyzing large functions and figuring out their capabilities and their address of occurance; for example: PEB access, RC4 encryption, etc.

To use this, you can copy the virtual addresses from your favorite disassembler and pass them to capa as follows: capa sample.exe --restrict-to-functions 0x4019C0,0x401CD0. If you add the -v option then capa will extract the interesting parts of a function for you.

only analyze selected processes

Use the --restrict-to-processes option to extract capabilities from only a selected set of processes. This is useful for filtering the noise generated from analyzing non-malicious processes that can be reported by some sandboxes, as well as reduce the execution time by not analyzing such processes in the first place.

To use this, you can pick the PIDs of the processes you are interested in from the sandbox-generated process tree (or from the sandbox-reported malware PID) and pass that to capa as follows: capa report.log --restrict-to-processes 3888,3214,4299. If you add the -v option then capa will tell you which threads perform what actions (encrypt/decrypt data, initiate a connection, etc.).

IDA Pro plugin: capa explorer

Please check out the capa explorer documentation.

save time by reusing .viv files

Set the environment variable CAPA_SAVE_WORKSPACE to instruct the underlying analysis engine to cache its intermediate results to the file system. For example, vivisect will create .viv files. Subsequently, capa may run faster when reprocessing the same input file. This is particularly useful during rule development as you repeatedly test a rule against a known sample.