Detection rules › Splunk
DLLRegisterServer Called from Command Line (PowerShell)
Threat actors including SocGhoulish may use explicit calls to DLLRegisterServer in the command line as a technique to register malicious DLLs, often bypassing standard registration methods like regsvr32. This use case detects instances where any process, including those masquerading as legitimate system utilities, explicitly invokes DLLRegisterServer in the command line. While such executions could be part of legitimate software installations or development activities, unexpected executions should be investigated.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1218.011 System Binary Proxy Execution: Rundll32 |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| PowerShell | Event ID 4104 | Creating Scriptblock text (MessageNumber of MessageTotal). |
Rule body yaml
id: '27166.49585'
title: DLLRegisterServer Called from Command Line
description: Threat actors including SocGhoulish may use explicit calls to DLLRegisterServer
in the command line as a technique to register malicious DLLs, often bypassing standard
registration methods like regsvr32. This use case detects instances where any process,
including those masquerading as legitimate system utilities, explicitly invokes
DLLRegisterServer in the command line. While such executions could be part of legitimate
software installations or development activities, unexpected executions should be
investigated.
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR
"<EventID>4104<") ".dll" "DLLRegisterServer" | where match(process, "(?i)\.dll\"?,DLLRegisterServer")
| 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:
- PowerShell logs
references:
- https://redcanary.com/blog/lolbins-abuse/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR "<EventID>4104<") ".dll" "DLLRegisterServer"
Stage 2: where
| where match(process, "(?i)\.dll\"?,DLLRegisterServer")
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>4104<" |
| 1 | ".dll" |
| 1 | "DLLRegisterServer" |