Detection rules › Splunk
hh.exe Execution (Windows Event Log)
Adversaries may abuse Compiled HTML files (.chm) to conceal malicious code. CHM files are commonly distributed as part of the Microsoft HTML Help system. A custom CHM file containing embedded payloads could be delivered to a victim then triggered by User Execution
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1218.001 System Binary Proxy Execution: Compiled HTML File |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '17974.30261'
title: hh.exe Execution
description: 'Adversaries may abuse Compiled HTML files (.chm) to conceal malicious
code. CHM files are commonly distributed as part of the Microsoft HTML Help system.
A custom CHM file containing embedded payloads could be delivered to a victim then
triggered by User Execution. -- Threat Actor Association: APT-K-47/Mysterious Elephant,
Gamaredon (aka. Armageddon, UAC-0010), Kimsuky -- LOLBAS Atomics T1218.001 Test
#1 Atomics T1218.001 Test #2 Atomics T1218.001 Test #3 Atomics T1218.001 Test #4
Atomics T1218.001 Test #5 Atomics T1218.001 Test #6 Atomics T1218.001 Test #7 Atomics
T1218.001 Test #8'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process) (TERM(hh) OR TERM(hh.exe)) | where match(process_name,
"(?i)hh\.exe") OR match(process, "(?i)hh\.exe") | table _time, host, user process,
process_*, parent_* | bin span=1s | stats values(*) as * by _time, host '
techniques:
- defense-evasion:system binary proxy execution:compiled html file
technique_id:
- T1218.001
data_category:
- Windows event logs
references:
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.001/T1218.001.md#atomic-test-8---decompile-local-chm-file
- https://www.ptsecurity.com/ww-en/analytics/pt-esc-threat-intelligence/higaisa-or-winnti-apt-41-backdoors-old-and-new/
- https://asec.ahnlab.com/en/51746/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process) (TERM(hh) OR TERM(hh.exe))
Stage 2: where
| where match(process_name, "(?i)hh\.exe") OR match(process, "(?i)hh\.exe")
Stage 3: table
| table _time, host, user process, process_*, parent_*
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 |
|
process | 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 | hh |
| 1 | TERM |
| 1 | hh.exe |