capa
capa detects capabilities in executable files. You run it against a PE file or shellcode and it tells you what it thinks the program can do. For example, it might suggest that the file is a backdoor, is capable of installing services, or relies on HTTP to communicate.
$ capa.exe suspicious.exe
+------------------------+--------------------------------------------------------------------------------+
| ATT&CK Tactic | ATT&CK Technique |
|------------------------+--------------------------------------------------------------------------------|
| DEFENSE EVASION | Obfuscated Files or Information [T1027] |
| DISCOVERY | Query Registry [T1012] |
| | System Information Discovery [T1082] |
| EXECUTION | Command and Scripting Interpreter::Windows Command Shell [T1059.003] |
| | Shared Modules [T1129] |
| EXFILTRATION | Exfiltration Over C2 Channel [T1041] |
| PERSISTENCE | Create or Modify System Process::Windows Service [T1543.003] |
+------------------------+--------------------------------------------------------------------------------+
+-------------------------------------------------------+-------------------------------------------------+
| CAPABILITY | NAMESPACE |
|-------------------------------------------------------+-------------------------------------------------|
| check for OutputDebugString error | anti-analysis/anti-debugging/debugger-detection |
| read and send data from client to server | c2/file-transfer |
| execute shell command and capture output | c2/shell |
| receive data (2 matches) | communication |
| send data (6 matches) | communication |
| connect to HTTP server (3 matches) | communication/http/client |
| send HTTP request (3 matches) | communication/http/client |
| create pipe | communication/named-pipe/create |
| get socket status (2 matches) | communication/socket |
| receive data on socket (2 matches) | communication/socket/receive |
| send data on socket (3 matches) | communication/socket/send |
| connect TCP socket | communication/socket/tcp |
| encode data using Base64 | data-manipulation/encoding/base64 |
| encode data using XOR (6 matches) | data-manipulation/encoding/xor |
| run as a service | executable/pe |
| get common file path (3 matches) | host-interaction/file-system |
| read file | host-interaction/file-system/read |
| write file (2 matches) | host-interaction/file-system/write |
| print debug messages (2 matches) | host-interaction/log/debug/write-event |
| resolve DNS | host-interaction/network/dns/resolve |
| get hostname | host-interaction/os/hostname |
| create a process with modified I/O handles and window | host-interaction/process/create |
| create process | host-interaction/process/create |
| create registry key | host-interaction/registry/create |
| create service | host-interaction/service/create |
| create thread | host-interaction/thread/create |
| persist via Windows service | persistence/service |
+-------------------------------------------------------+-------------------------------------------------+
Changelog v3.0
- adds support for ELF files targeting Linux thanks to Intezer
- adds new features to specify OS, CPU architecture, and file format
- fixes a few bugs that may have led to false negatives (missed capabilities) in older versions
- adds 80 new rules, including 36 describing techniques for Linux
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.
IDA Pro integrations
You can run capa from within IDA Pro. Run capa/main.py via File - Script file... (or ALT + F7). When running in IDA, capa uses IDA’s disassembly and file analysis as its backend. These results may vary from the standalone version that uses vivisect. IDA’s analysis is generally a bit faster and more thorough than vivisect’s, so you might prefer this mode.
When run under IDA, capa supports both Python 2 and Python 3 interpreters. If you encounter issues with your specific setup, please open a new Issue.
Additionally, capa comes with an IDA Pro plugin located in the capa/ida directory: the explorer.
capa explorer
The capa explorer allows you to interactively display and browse capabilities capa identified in a binary. As you select rules or logic, capa will highlight the addresses that support its analysis conclusions. We like to use capa to help find the most interesting parts of a program, such as where the C2 mechanism might be.
To install the plugin, you’ll need to be running IDA Pro 7.4 or 7.5 with either Python 2 or Python 3. Next make sure pip commands are run using the Python install that is configured for your IDA install:
- Only if running Python 2.7, run command
$ pip install https://github.com/williballenthin/vivisect/zipball/master
- Run
$ pip install . from capa root directory
- Open IDA and navigate to
File > Script file… or Alt+F7
- Navigate to
<capa_install_dir>\capa\ida\ and choose ida_capa_explorer.py
Copyright (C) 2020 FireEye
