ID | Technique | Tactic |
---|---|---|
T1190 | Exploit Public-Facing Application | Initial Access |
Detection: Splunk Unauthenticated Log Injection Web Service Log
Description
The following analytic identifies potential log injection attempts into the Splunk server via specially crafted web URLs. It detects ANSI escape codes within the uri_path
field of splunkd_webx
logs. This activity is significant as it can lead to log file manipulation, potentially obfuscating malicious actions or misleading analysts. If confirmed malicious, an attacker could manipulate log files to hide their tracks or execute further attacks, compromising the integrity of the logging system and making incident response more challenging.
Search
1`splunkd_webx` uri_path IN ("*\x1B*", "*\u001b*", "*\033*", "*\0x9*", "*\0x8*")
2| stats count by uri_path method host status clientip
3| `splunk_unauthenticated_log_injection_web_service_log_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
Splunk | Splunk | 'splunkd_ui_access' |
'splunkd_ui_access.log' |
Macros Used
Name | Value |
---|---|
splunkd_webx | index=_internal sourcetype=splunk_web_access |
splunk_unauthenticated_log_injection_web_service_log_filter | search * |
splunk_unauthenticated_log_injection_web_service_log_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Risk Event | False |
Implementation
This only affects web enabled Splunk instances. The detection does require the ability to search the _internal index.
Known False Positives
This hunting search will produce false positives if ANSI escape characters are included in URLs either voluntarily or by accident. This search will not detect obfuscated ANSI characters.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
Possible Splunk unauthenticated log injection web service log exploitation attempt against $host$ from $clientip$ | 9 | 30 | 30 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | /opt/splunk/var/log/splunk/web_access.log |
splunk_web_access |
Integration | ✅ Passing | Dataset | /opt/splunk/var/log/splunk/web_access.log |
splunk_web_access |
Replay any dataset to Splunk Enterprise by using our replay.py
tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
Source: GitHub | Version: 2