Detection rules › Splunk
Rundll32 Suspicious Command Line (Sysmon)
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 |
References
Telemetry coverage
| Provider | Record / event type |
|---|---|
| Sysmon | Event ID 1: Process creation |
Rule body
id: '27224.49776'
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_sysmon` (TERM(EventCode=1) OR "<EventID>1<")
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:
- Windows Sysmon
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_sysmon` (TERM(EventCode=1) OR "<EventID>1<") 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
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
EventCode | eq |
| field:"EventID" kind:eq value:"1" |
process | regex_match |
| field:"CommandLine" kind:regex_match |
Search terms
These SPL tokens match against raw event text.
| Stage | Term |
|---|---|
| 1 | "<EventID>1<" |
| 1 | rundll32 |
| 1 | "rundll32" |