| 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 | Supported App |
|---|---|---|---|---|
| Splunk |  Splunk |
'splunkd_ui_access' |
'splunkd_ui_access.log' |
N/A |
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
MITRE ATT&CK
Kill Chain Phases
NIST
CIS
Threat Actors
KillChainPhase.DELIVERY
NistCategory.DE_AE
Cis18Value.CIS_10
APT28
APT29
APT39
APT41
APT5
Axiom
BackdoorDiplomacy
BlackTech
Blue Mockingbird
Cinnamon Tempest
Dragonfly
Earth Lusca
FIN13
FIN7
Fox Kitten
GALLIUM
GOLD SOUTHFIELD
HAFNIUM
Ke3chang
Kimsuky
Magic Hound
Moses Staff
MuddyWater
Rocke
Sandworm Team
Threat Group-3390
ToddyCat
Volatile Cedar
Volt Typhoon
menuPass
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 |
This configuration file applies to all detections of type hunting.
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 |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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