Detection rules › Splunk
Browser Started with Remote Debugging - Windows (Windows Event Log)
Threat actors may abuse browser remote debugging features to extract sensitive data, maintain access, or facilitate communication with C2 servers. This is typically done by launching the browser with specific remote debugging flags, allowing remote access to browser sessions and potentially bypassing traditional security controls. This use case detects instances where a browser is started in remote debugging mode.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Collection | T1185 Browser Session Hijacking |
References
- https://yoroi.company/wp-content/uploads/2022/05/EternityGroup_report_compressed.pdf
- https://www.mdsec.co.uk/2022/10/analysing-lastpass-part-1/
- https://github.com/defaultnamehere/cookie_crimes/
- https://github.com/wunderwuzzi23/firefox-cookiemonster
- https://www.trendmicro.com/en_us/research/25/c/ai-assisted-fake-github-repositories.html
- https://cyble.com/blog/fake-coding-challenges-steal-sensitive-data-via-fogdoor/
- https://detection.fyi/sigmahq/sigma/windows/process_creation/proc_creation_win_browsers_remote_debugging/
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '44220.86860'
title: Browser Started with Remote Debugging - Windows
description: Threat actors may abuse browser remote debugging features to extract
sensitive data, maintain access, or facilitate communication with C2 servers. This
is typically done by launching the browser with specific remote debugging flags,
allowing remote access to browser sessions and potentially bypassing traditional
security controls. This use case detects instances where a browser is started in
remote debugging mode.
logic_format: Splunk
logic: ' `get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process) (TERM(Firefox) " -start-debugger-service") OR
" --remote-debugging-" | where match(process, "(?i)\s+--remote-debugging-\S+") or
(process="firefox.exe" and match(process, "(?i)\s+-start-debugger-service")) | table
_time, host, user, process, parent_process_name, process_path | bin span=1s | stats
values(*) as * by _time, host '
techniques:
- collection:browser session hijacking
technique_id:
- T1185
data_category:
- Process command-line parameters
- Windows event logs
references:
- https://yoroi.company/wp-content/uploads/2022/05/EternityGroup_report_compressed.pdf
- https://www.mdsec.co.uk/2022/10/analysing-lastpass-part-1/
- https://github.com/defaultnamehere/cookie_crimes/
- https://github.com/wunderwuzzi23/firefox-cookiemonster
- https://www.trendmicro.com/en_us/research/25/c/ai-assisted-fake-github-repositories.html
- https://cyble.com/blog/fake-coding-challenges-steal-sensitive-data-via-fogdoor/
- https://detection.fyi/sigmahq/sigma/windows/process_creation/proc_creation_win_browsers_remote_debugging/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process) (TERM(Firefox) " -start-debugger-service") OR " --remote-debugging-"
Stage 2: where
| where match(process, "(?i)\s+--remote-debugging-\S+") or (process="firefox.exe" and match(process, "(?i)\s+-start-debugger-service"))
Stage 3: table
| table _time, host, user, process, parent_process_name, process_path
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>4688<" |
| 1 | TERM |
| 1 | Firefox |
| 1 | " -start-debugger-service" |
| 1 | " --remote-debugging-" |