Rundll32 Command Line (PowerShell)

Group by: _time, host
Source: github.com/anvilogic-forge/armory

Adversaries may abuse rundll32.exe to proxy execution of malicious code. Using rundll32.exe, may avoid triggering security tools that may not monitor execution of the rundll32.exe process because of allowlists or false positives from normal operations. Rundll32.exe is commonly associated with executing DLL payloads. This use case specifically looks for command line argument executions with rundll32

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1218.011` System Binary Proxy Execution: Rundll32

References

https://redcanary.com/threat-detection-report/techniques/rundll32/

Telemetry coverage

Provider	Record / event type
PowerShell	Event ID 4103: Payload Context: ContextInfo User Data: UserData.
PowerShell	Event ID 4104: Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body

id: '5851.6130'
title: Rundll32 Command Line
description: 'Adversaries may abuse rundll32.exe to proxy execution of malicious code.
  Using rundll32.exe, may avoid triggering security tools that may not monitor execution
  of the rundll32.exe process because of allowlists or false positives from normal
  operations. Rundll32.exe is commonly associated with executing DLL payloads. This
  use case specifically looks for command line argument executions with rundll32.
  -- Threat Actor Association: Alloy Taurus/Gallium, APT-K-47/Mysterious Elephant,
  APT29/Nobelium/Cozy Bear, APT35/Phosphorus/Magic Hound, FIN7, MuddyWater, Night
  Spider, TA413, TA551, Witchetty, Wizard Spider - Software Association: ALPHV/BlackCat,
  Bazar, Black Basta, Clop, Conti, Hancitor, HermeticWizard, Hive, IcedID, LOWZERO,
  MINEBRIDGE, PowerShortShell, PYSA/Mespinoza, Quantum, Qakbot/Qbot, Ransom Cartel,
  RATDispenser, Rhysida, Sodinokibi/REvil, SquirrelWaffle, Trickbot, XingLocker --
  Atomics T1218.011 Test#1 Atomics T1218.011 Test#2 Atomics T1218.011 Test#3 Atomics
  T1218.011 Test#4 Atomics T1218.011 Test#5 Atomics T1218.011 Test#6 Atomics T1218.011
  Test#7 Atomics T1218.011 Test#8'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR
  TERM(EventCode=4103)) ("rundll32.exe" OR "rundll32") | rex field=_raw (?<process_msg>"(?i)rundll32.{1,40}")
  | table _time, host, user process, process_name, signature_id, process_msg | bin
  span=1s | stats values(*) as * by _time, host '
techniques:
- defense-evasion:system binary proxy execution:rundll32
technique_id:
- T1218.011
data_category:
- Process command-line parameters
- PowerShell logs
references:
- https://redcanary.com/threat-detection-report/techniques/rundll32/

Stages and Predicates

Stage 1: `search`

`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR TERM(EventCode=4103)) ("rundll32.exe" OR "rundll32")

Stage 2: `rex`

| rex field=_raw (?<process_msg>"(?i)rundll32.{1,40}")

Stage 3: `table`

| table _time, host, user process, process_name, signature_id, process_msg

Stage 4: `bucket`

| bin span=1s

Stage 5: `stats`

| stats values(*) as * by _time, host

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventCode`	eq	`4103` corpus 105 (splunk 105) `4104` corpus 269 (splunk 269)	`field:"EventID" kind:eq`

Search terms

These SPL tokens match against raw event text.

Stage	Term
1	`"rundll32.exe"`
1	`"rundll32"`