Detection rules › Splunk
ngrok Execution - Windows (Windows Event Log)
Ngrok is a legitimate reverse proxy tool that can create a secure tunnel to servers located behind firewalls or on local machines that do not have a public IP. Ngrok has been leveraged by threat actors in several campaigns including use for lateral movement and data exfiltration. This use case detects process creation events for ngrok.exe or command patterns likely to be unique to ngrok in the event of a renamed executable
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Command & Control | T1572 Protocol Tunneling |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '20685.36863'
title: ngrok Execution - Windows
description: 'Ngrok is a legitimate reverse proxy tool that can create a secure tunnel
to servers located behind firewalls or on local machines that do not have a public
IP. Ngrok has been leveraged by threat actors in several campaigns including use
for lateral movement and data exfiltration. This use case detects process creation
events for ngrok.exe or command patterns likely to be unique to ngrok in the event
of a renamed executable. -- Threat Actor Association: Scattered Spider (aka. Muddled
Libra, Scatter Swine, Starfraud, UNC3944)'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process) TERM(ngrok) OR (TERM(start) "--all" "--config"
".yml") OR (TERM(tcp) ("139" OR "445" OR "3389" OR "5985" OR "5986")) | where match(process,
"(?i)(tcp\s+(139|445|3389|5985|5986))|(\.exe\s+|(authtoken\s|start\s+--all))|(start\s.*\s--all\s.*\s--config\s.+\.yml)")
OR match(process_path, "(?i)ngrok\.exe") | table _time, host, user, signature_id,
process, process_*, parent_process_* | bin span=1s | stats values(*) as * by _time,
host '
techniques:
- command-and-control:protocol tunneling
technique_id:
- T1572
data_category:
- Process command-line parameters
- Windows event logs
references:
- https://www.logpoint.com/en/blog/a-deep-look-at-the-darkside-ransomware-operators-and-their-affiliates/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process) TERM(ngrok) OR (TERM(start) "--all" "--config" ".yml") OR (TERM(tcp) ("139" OR "445" OR "3389" OR "5985" OR "5986"))
Stage 2: where
| where match(process, "(?i)(tcp\s+(139|445|3389|5985|5986))|(\.exe\s+|(authtoken\s|start\s+--all))|(start\s.*\s--all\s.*\s--config\s.+\.yml)") OR match(process_path, "(?i)ngrok\.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 |
|
process | match |
|
process_path | 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 | ngrok |
| 1 | TERM |
| 1 | start |
| 1 | "--all" |
| 1 | "--config" |
| 1 | ".yml" |
| 1 | TERM |
| 1 | tcp |
| 1 | "139" |
| 1 | "445" |
| 1 | "3389" |
| 1 | "5985" |
| 1 | "5986" |