Detection rules › Splunk
1 or 2 Character Executable (Windows Event Log)
Adversaries have been known to occasionally use executable files named with only 1 or 2 word characters
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Execution | T1059 Command and Scripting Interpreter |
| Stealth | T1036 Masquerading |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '6142.6639'
title: 1 or 2 Character Executable
description: 'Adversaries have been known to occasionally use executable files named
with only 1 or 2 word characters. - Threat Actor Association: Lotus Blossom, OilRig,
Trigona, Volt Typhoon'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process OR TERM(ingress.event.procstart)) NOT "sc.exe"
| where match(parent_process_name, "(?i)^\w{1,2}\.exe") OR match(process_name, "(?i)^\w{1,2}\.exe")
| table _time, host, user, signature_id, process, process_*, parent_process_* |
bin span=1s | stats values(*) as * by _time, host '
techniques:
- execution:command and scripting interpreter
- defense-evasion:masquerading
technique_id:
- T1059
- T1036
data_category:
- Windows event logs
references:
- https://www.proofpoint.com/us/threat-insight/post/operation-rat-cook-chinese-apt-actors-use-fake-game-thrones-leaks-lures
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process OR TERM(ingress.event.procstart)) NOT "sc.exe"
Stage 2: where
| where match(parent_process_name, "(?i)^\w{1,2}\.exe") OR match(process_name, "(?i)^\w{1,2}\.exe")
Stage 3: table
| table _time, host, user, signature_id, 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.
| Field | Kind | Values |
|---|---|---|
EventCode | eq |
|
parent_process_name | match |
|
process_name | 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 | TERM |
| 1 | ingress.event.procstart |
| 1 | "sc.exe" |