Detection rules › Splunk
Suspicious Child Process for mshta.exe (Windows Event Log)
This use case detects when mshta.exe spawns an unexpected child process. This can indicate process injection/hollowing, masquerading, application allowlist bypass, or other suspicious activity.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Execution | T1059 Command and Scripting Interpreter |
| Stealth | T1218.005 System Binary Proxy Execution: Mshta |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '23910.44203'
title: Suspicious Child Process for mshta.exe
description: This use case detects when mshta.exe spawns an unexpected child process.
This can indicate process injection/hollowing, masquerading, application allowlist
bypass, or other suspicious activity.
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process) "mshta.exe" ("powershell.exe" OR "pwsh.exe" OR
"cmd.exe" OR "rundll32.exe" OR "cscript.exe" OR "wscript.exe") | regex parent_process_name="(?i)(mshta\.exe)"
| regex process_path="(?i)(cmd|services|powershell|pwsh|(c|w)script)|rundll32\.exe"
| table _time, host, user process, process_*, parent_process_name, parent_process_*
| bin span=1s | stats values(*) as * by _time, host '
techniques:
- execution:command and scripting interpreter
- defense-evasion:system binary proxy execution:mshta
technique_id:
- T1059
- T1218.005
data_category:
- Windows event logs
references:
- https://blog.talosintelligence.com/gamaredon-apt-targets-ukrainian-agencies/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process) "mshta.exe" ("powershell.exe" OR "pwsh.exe" OR "cmd.exe" OR "rundll32.exe" OR "cscript.exe" OR "wscript.exe")
Stage 2: regex
| regex parent_process_name="(?i)(mshta\.exe)"
Stage 3: regex
| regex process_path="(?i)(cmd|services|powershell|pwsh|(c|w)script)|rundll32\.exe"
Stage 4: table
| table _time, host, user process, process_*, parent_process_name, parent_process_*
Stage 5: bucket
| bin span=1s
Stage 6: 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.
| Field | Kind | Values |
|---|---|---|
EventCode | eq |
|
parent_process_name | regex_match |
|
process_path | 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>4688<" |
| 1 | "mshta.exe" |
| 1 | "powershell.exe" |
| 1 | "pwsh.exe" |
| 1 | "cmd.exe" |
| 1 | "rundll32.exe" |
| 1 | "cscript.exe" |
| 1 | "wscript.exe" |