Detection rules › Splunk
Rundll32 Suspicious Command Line (Windows Event Log)
Threat actors using Gamarue, also referred to as Andromeda or Wauchos, have been observed abusing rundll32.exe using unusual strings for DLL names. This use case detects rundll32 executions with strings matching unusual patterns
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1218.011 System Binary Proxy Execution: Rundll32 |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '27224.49649'
title: Rundll32 Suspicious Command Line
description: Threat actors using Gamarue, also referred to as Andromeda or Wauchos,
have been observed abusing rundll32.exe using unusual strings for DLL names. This
use case detects rundll32 executions with strings matching unusual patterns. Living
Off the Land Binary and Scripts (LOLBAS) (LOLBIN)
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process) TERM(rundll32) OR "rundll32" | regex process="\x5c\x5c?[-_]{2,}[-_]{2,}[-_]{2,}.+,"|
table _time, host, user, process, process_*, parent_process_* | 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
- Windows event logs
references:
- https://redcanary.com/threat-detection-report/threats/gamarue/
- https://redcanary.com/blog/lolbins-abuse/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process) TERM(rundll32) OR "rundll32"
Stage 2: regex
| regex process="\x5c\x5c?[-_]{2,}[-_]{2,}[-_]{2,}.+,"
Stage 3: table
| table _time, host, user, process, process_*, parent_process_*
Stage 4: bucket
| bin span=1s
Stage 5: stats
| stats values(*) as * by _time, host
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
Search terms
Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.
| Stage | Term |
|---|---|
| 1 | TERM |
| 1 | "<EventID>4688<" |
| 1 | TERM |
| 1 | rundll32 |
| 1 | "rundll32" |