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277 lines
22 KiB
Markdown
277 lines
22 KiB
Markdown
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[](https://pypi.org/project/flare-capa)
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[](https://github.com/mandiant/capa/releases)
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[](https://github.com/mandiant/capa-rules)
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[](https://github.com/mandiant/capa/actions?query=workflow%3ACI+event%3Apush+branch%3Amaster)
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[](https://github.com/mandiant/capa/releases)
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[](LICENSE.txt)
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capa detects capabilities in executable files.
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You run it against a PE, ELF, .NET module, shellcode file, or a sandbox report and it tells you what it thinks the program can do.
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For example, it might suggest that the file is a backdoor, is capable of installing services, or relies on HTTP to communicate.
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Check out:
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- the overview in our first [capa blog post](https://www.mandiant.com/resources/capa-automatically-identify-malware-capabilities)
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- the major version 2.0 updates described in our [second blog post](https://www.mandiant.com/resources/capa-2-better-stronger-faster)
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- the major version 3.0 (ELF support) described in the [third blog post](https://www.mandiant.com/resources/elfant-in-the-room-capa-v3)
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- the major version 4.0 (.NET support) described in the [fourth blog post](https://www.mandiant.com/resources/blog/capa-v4-casting-wider-net)
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```
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$ capa.exe suspicious.exe
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+------------------------+--------------------------------------------------------------------------------+
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| ATT&CK Tactic | ATT&CK Technique |
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|------------------------+--------------------------------------------------------------------------------|
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| DEFENSE EVASION | Obfuscated Files or Information [T1027] |
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| DISCOVERY | Query Registry [T1012] |
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| | System Information Discovery [T1082] |
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| EXECUTION | Command and Scripting Interpreter::Windows Command Shell [T1059.003] |
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| | Shared Modules [T1129] |
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| EXFILTRATION | Exfiltration Over C2 Channel [T1041] |
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| PERSISTENCE | Create or Modify System Process::Windows Service [T1543.003] |
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+------------------------+--------------------------------------------------------------------------------+
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+-------------------------------------------------------+-------------------------------------------------+
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| CAPABILITY | NAMESPACE |
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|-------------------------------------------------------+-------------------------------------------------|
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| check for OutputDebugString error | anti-analysis/anti-debugging/debugger-detection |
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| read and send data from client to server | c2/file-transfer |
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| execute shell command and capture output | c2/shell |
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| receive data (2 matches) | communication |
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| send data (6 matches) | communication |
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| connect to HTTP server (3 matches) | communication/http/client |
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| send HTTP request (3 matches) | communication/http/client |
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| create pipe | communication/named-pipe/create |
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| get socket status (2 matches) | communication/socket |
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| receive data on socket (2 matches) | communication/socket/receive |
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| send data on socket (3 matches) | communication/socket/send |
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| connect TCP socket | communication/socket/tcp |
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| encode data using Base64 | data-manipulation/encoding/base64 |
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| encode data using XOR (6 matches) | data-manipulation/encoding/xor |
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| run as a service | executable/pe |
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| get common file path (3 matches) | host-interaction/file-system |
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| read file | host-interaction/file-system/read |
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| write file (2 matches) | host-interaction/file-system/write |
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| print debug messages (2 matches) | host-interaction/log/debug/write-event |
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| resolve DNS | host-interaction/network/dns/resolve |
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| get hostname | host-interaction/os/hostname |
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| create a process with modified I/O handles and window | host-interaction/process/create |
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| create process | host-interaction/process/create |
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| create registry key | host-interaction/registry/create |
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| create service | host-interaction/service/create |
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| create thread | host-interaction/thread/create |
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| persist via Windows service | persistence/service |
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+-------------------------------------------------------+-------------------------------------------------+
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```
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# download and usage
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Download stable releases of the standalone capa binaries [here](https://github.com/mandiant/capa/releases). You can run the standalone binaries without installation. capa is a command line tool that should be run from the terminal.
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To use capa as a library or integrate with another tool, see [doc/installation.md](https://github.com/mandiant/capa/blob/master/doc/installation.md) for further setup instructions.
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For more information about how to use capa, see [doc/usage.md](https://github.com/mandiant/capa/blob/master/doc/usage.md).
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# example
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In the above sample output, we ran capa against an unknown binary (`suspicious.exe`),
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and the tool reported that the program can send HTTP requests, decode data via XOR and Base64,
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install services, and spawn new processes.
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Taken together, this makes us think that `suspicious.exe` could be a persistent backdoor.
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Therefore, our next analysis step might be to run `suspicious.exe` in a sandbox and try to recover the command and control server.
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By passing the `-vv` flag (for very verbose), capa reports exactly where it found evidence of these capabilities.
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This is useful for at least two reasons:
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- it helps explain why we should trust the results, and enables us to verify the conclusions, and
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- it shows where within the binary an experienced analyst might study with IDA Pro
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```
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$ capa.exe suspicious.exe -vv
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...
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execute shell command and capture output
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namespace c2/shell
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author matthew.williams@mandiant.com
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scope function
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att&ck Execution::Command and Scripting Interpreter::Windows Command Shell [T1059.003]
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references https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/ns-processthreadsapi-startupinfoa
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function @ 0x4011C0
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and:
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match: create a process with modified I/O handles and window @ 0x4011C0
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and:
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number: 257 = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW @ 0x4012B8
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or:
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number: 68 = StartupInfo.cb (size) @ 0x401282
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or: = API functions that accept a pointer to a STARTUPINFO structure
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api: kernel32.CreateProcess @ 0x401343
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match: create pipe @ 0x4011C0
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or:
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api: kernel32.CreatePipe @ 0x40126F, 0x401280
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optional:
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match: create thread @ 0x40136A, 0x4013BA
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or:
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and:
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os: windows
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or:
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api: kernel32.CreateThread @ 0x4013D7
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or:
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and:
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os: windows
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or:
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api: kernel32.CreateThread @ 0x401395
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or:
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string: "cmd.exe" @ 0x4012FD
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...
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```
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Additionally, capa also supports analyzing [CAPE](https://github.com/kevoreilly/CAPEv2) sandbox reports for dynamic capabilty extraction.
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In order to use this, you first submit your sample to CAPE for analysis, and then run capa against the generated report (JSON).
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Here's an example of running capa against a packed binary, and then running capa against the CAPE report of that binary:
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```yaml
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$ capa 05be49819139a3fdcdbddbdefd298398779521f3d68daa25275cc77508e42310.exe
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WARNING:capa.capabilities.common:--------------------------------------------------------------------------------
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WARNING:capa.capabilities.common: This sample appears to be packed.
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WARNING:capa.capabilities.common:
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WARNING:capa.capabilities.common: Packed samples have often been obfuscated to hide their logic.
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WARNING:capa.capabilities.common: capa cannot handle obfuscation well using static analysis. This means the results may be misleading or incomplete.
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WARNING:capa.capabilities.common: If possible, you should try to unpack this input file before analyzing it with capa.
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WARNING:capa.capabilities.common: Alternatively, run the sample in a supported sandbox and invoke capa against the report to obtain dynamic analysis results.
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WARNING:capa.capabilities.common:
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WARNING:capa.capabilities.common: Identified via rule: (internal) packer file limitation
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WARNING:capa.capabilities.common:
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WARNING:capa.capabilities.common: Use -v or -vv if you really want to see the capabilities identified by capa.
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WARNING:capa.capabilities.common:--------------------------------------------------------------------------------
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$ capa 05be49819139a3fdcdbddbdefd298398779521f3d68daa25275cc77508e42310.json
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┍━━━━━━━━━━━━━━━━━━━━━━━━┯━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┑
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│ ATT&CK Tactic │ ATT&CK Technique │
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┝━━━━━━━━━━━━━━━━━━━━━━━━┿━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┥
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│ CREDENTIAL ACCESS │ Credentials from Password Stores T1555 │
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├────────────────────────┼────────────────────────────────────────────────────────────────────────────────────┤
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│ DEFENSE EVASION │ File and Directory Permissions Modification T1222 │
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│ │ Modify Registry T1112 │
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│ │ Obfuscated Files or Information T1027 │
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│ │ Virtualization/Sandbox Evasion::User Activity Based Checks T1497.002 │
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├────────────────────────┼────────────────────────────────────────────────────────────────────────────────────┤
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│ DISCOVERY │ Account Discovery T1087 │
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│ │ Application Window Discovery T1010 │
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│ │ File and Directory Discovery T1083 │
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│ │ Query Registry T1012 │
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│ │ System Information Discovery T1082 │
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│ │ System Location Discovery::System Language Discovery T1614.001 │
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│ │ System Owner/User Discovery T1033 │
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├────────────────────────┼────────────────────────────────────────────────────────────────────────────────────┤
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│ EXECUTION │ System Services::Service Execution T1569.002 │
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├────────────────────────┼────────────────────────────────────────────────────────────────────────────────────┤
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│ PERSISTENCE │ Boot or Logon Autostart Execution::Registry Run Keys / Startup Folder T1547.001 │
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│ │ Boot or Logon Autostart Execution::Winlogon Helper DLL T1547.004 │
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│ │ Create or Modify System Process::Windows Service T1543.003 │
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┕━━━━━━━━━━━━━━━━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┙
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┍━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┯━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┑
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│ Capability │ Namespace │
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┝━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┿━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┥
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│ check for unmoving mouse cursor (3 matches) │ anti-analysis/anti-vm/vm-detection │
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│ gather bitkinex information │ collection/file-managers │
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│ gather classicftp information │ collection/file-managers │
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│ gather filezilla information │ collection/file-managers │
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│ gather total-commander information │ collection/file-managers │
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│ gather ultrafxp information │ collection/file-managers │
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│ resolve DNS (23 matches) │ communication/dns │
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│ initialize Winsock library (7 matches) │ communication/socket │
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│ act as TCP client (3 matches) │ communication/tcp/client │
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│ create new key via CryptAcquireContext │ data-manipulation/encryption │
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│ encrypt or decrypt via WinCrypt │ data-manipulation/encryption │
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│ hash data via WinCrypt │ data-manipulation/hashing │
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│ initialize hashing via WinCrypt │ data-manipulation/hashing │
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│ hash data with MD5 │ data-manipulation/hashing/md5 │
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│ generate random numbers via WinAPI │ data-manipulation/prng │
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│ extract resource via kernel32 functions (2 matches) │ executable/resource │
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│ interact with driver via control codes (2 matches) │ host-interaction/driver │
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│ get Program Files directory (18 matches) │ host-interaction/file-system │
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│ get common file path (575 matches) │ host-interaction/file-system │
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│ create directory (2 matches) │ host-interaction/file-system/create │
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│ delete file │ host-interaction/file-system/delete │
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│ get file attributes (122 matches) │ host-interaction/file-system/meta │
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│ set file attributes (8 matches) │ host-interaction/file-system/meta │
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│ move file │ host-interaction/file-system/move │
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│ find taskbar (3 matches) │ host-interaction/gui/taskbar/find │
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│ get keyboard layout (12 matches) │ host-interaction/hardware/keyboard │
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│ get disk size │ host-interaction/hardware/storage │
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│ get hostname (4 matches) │ host-interaction/os/hostname │
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│ allocate or change RWX memory (3 matches) │ host-interaction/process/inject │
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│ query or enumerate registry key (3 matches) │ host-interaction/registry │
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│ query or enumerate registry value (8 matches) │ host-interaction/registry │
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│ delete registry key │ host-interaction/registry/delete │
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│ start service │ host-interaction/service/start │
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│ get session user name │ host-interaction/session │
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│ persist via Run registry key │ persistence/registry/run │
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│ persist via Winlogon Helper DLL registry key │ persistence/registry/winlogon-helper │
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│ persist via Windows service (2 matches) │ persistence/service │
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┕━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┙
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```
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capa uses a collection of rules to identify capabilities within a program.
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These rules are easy to write, even for those new to reverse engineering.
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By authoring rules, you can extend the capabilities that capa recognizes.
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In some regards, capa rules are a mixture of the OpenIOC, Yara, and YAML formats.
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Here's an example rule used by capa:
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```yaml
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rule:
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meta:
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name: create TCP socket
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namespace: communication/socket/tcp
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authors:
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- william.ballenthin@mandiant.com
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- joakim@intezer.com
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- anushka.virgaonkar@mandiant.com
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scopes:
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static: basic block
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dynamic: call
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mbc:
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- Communication::Socket Communication::Create TCP Socket [C0001.011]
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examples:
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- Practical Malware Analysis Lab 01-01.dll_:0x10001010
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features:
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- or:
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- and:
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- number: 6 = IPPROTO_TCP
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- number: 1 = SOCK_STREAM
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- number: 2 = AF_INET
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- or:
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- api: ws2_32.socket
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- api: ws2_32.WSASocket
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- api: socket
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- property/read: System.Net.Sockets.TcpClient::Client
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```
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The [github.com/mandiant/capa-rules](https://github.com/mandiant/capa-rules) repository contains hundreds of standard library rules that are distributed with capa.
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Please learn to write rules and contribute new entries as you find interesting techniques in malware.
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If you use IDA Pro, then you can use the [capa explorer](https://github.com/mandiant/capa/tree/master/capa/ida/plugin) plugin.
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capa explorer helps you identify interesting areas of a program and build new capa rules using features extracted directly from your IDA Pro database.
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If you use Ghidra, you can use the Python 3 [Ghidra feature extractor](/capa/ghidra/). This integration enables capa to extract features directly from your Ghidra database, which can help you identify capabilities in programs that you analyze using Ghidra.
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# further information
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## capa
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- [Installation](https://github.com/mandiant/capa/blob/master/doc/installation.md)
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- [Usage](https://github.com/mandiant/capa/blob/master/doc/usage.md)
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- [Limitations](https://github.com/mandiant/capa/blob/master/doc/limitations.md)
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- [Contributing Guide](https://github.com/mandiant/capa/blob/master/.github/CONTRIBUTING.md)
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## capa rules
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- [capa-rules repository](https://github.com/mandiant/capa-rules)
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- [capa-rules rule format](https://github.com/mandiant/capa-rules/blob/master/doc/format.md)
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## capa testfiles
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The [capa-testfiles repository](https://github.com/mandiant/capa-testfiles) contains the data we use to test capa's code and rules
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