Detection rules › Splunk
rundll32 Suspicious Parent Process (Sysmon)
Expected legitimate parent processes for rundll32 include svchost, explorer, spoolsv, and rundll32 itself. This use case detects executions of rundll32 with parent process names that are commonly targeted by threat actors for abuse
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1218.011 System Binary Proxy Execution: Rundll32 |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
Rule body yaml
id: '27464.49949'
title: rundll32 Suspicious Parent Process
description: Expected legitimate parent processes for rundll32 include svchost, explorer,
spoolsv, and rundll32 itself. This use case detects executions of rundll32 with
parent process names that are commonly targeted by threat actors for abuse. 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<")
"rundll32.exe" OR TERM(rundll32) | regex parent_process_name="(?i)(winword|excel|powerpnt|onenote|msaccess|lsass|taskeng|winlogon|schtask|regsvr32|wmiprvse|wsmprovhost|chrome|firefox|msedge|opera|iexplore|outlook|thunderbird|powershell|pwsh|cmd|wscript|cscript)\.exe"|
where not (match(parent_process_name, "(?i)iexplore\.exe") and match(process, "(?i)C:\x5cWindows\x5csystem32\x5cinetcpl\.cpl,ClearMyTracksByProcess"))|
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/blog/lolbins-abuse/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<") "rundll32.exe" OR TERM(rundll32)
Stage 2: regex
| regex parent_process_name="(?i)(winword|excel|powerpnt|onenote|msaccess|lsass|taskeng|winlogon|schtask|regsvr32|wmiprvse|wsmprovhost|chrome|firefox|msedge|opera|iexplore|outlook|thunderbird|powershell|pwsh|cmd|wscript|cscript)\.exe"
Stage 3: where
| where not (match(parent_process_name, "(?i)iexplore\.exe") and match(process, "(?i)C:\x5cWindows\x5csystem32\x5cinetcpl\.cpl,ClearMyTracksByProcess"))
Stage 4: table
| table _time, host, user, process, process_*, parent_process_*
Stage 5: bucket
| bin span=1s
Stage 6: stats
| stats values(*) as * by _time, host
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
parent_process_name | match | "(?i)iexplore\.exe" |
process | match | "(?i)C:\x5cWindows\x5csystem32\x5cinetcpl\.cpl,ClearMyTracksByProcess" |
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.
| Field | Kind | Values |
|---|---|---|
EventCode | eq |
|
parent_process_name | regex_match |
|
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>1<" |
| 1 | "rundll32.exe" |
| 1 | TERM |
| 1 | rundll32 |