Detection: Suspicious Event Log Service Behavior

Updated Date: 2024-05-14 ID: 2b85aa3d-f5f6-4c2e-a081-a09f6e1c2e40 Author: Mauricio Velazco, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects the shutdown of the Windows Event Log service using Windows Event ID 1100. This event is logged every time the service stops, including during normal system shutdowns. Monitoring this activity is crucial as it can indicate attempts to cover tracks or disable logging. If confirmed malicious, an attacker could hide their activities, making it difficult to trace their actions and investigate further incidents. Analysts should verify if the shutdown was planned and review other alerts and data sources for additional suspicious behavior.

Search

1(`wineventlog_security` EventCode=1100) 
2| stats count min(_time) as firstTime max(_time) as lastTime by dest name EventCode 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)`
5| `suspicious_event_log_service_behavior_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Windows Event Log Security 1100	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Security'`	N/A

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
suspicious_event_log_service_behavior_filter	`search *`

suspicious_event_log_service_behavior_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

ID	Technique	Tactic
T1070	Indicator Removal	Defense Evasion
T1070.001	Clear Windows Event Logs	Defense Evasion

KillChainPhase.EXPLOITAITON

NistCategory.DE_AE

Cis18Value.CIS_10

APT5

Lazarus Group

APT28

APT32

APT38

APT41

Chimera

Dragonfly

FIN5

FIN8

Indrik Spider

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

To successfully implement this search, you need to be ingesting Windows event logs from your hosts. In addition, the Splunk Windows TA is needed.

Known False Positives

It is possible the Event Logging service gets shut down due to system errors or legitimately administration tasks. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
The Windows Event Log Service shutdown on $dest$	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	`XmlWinEventLog:Security`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Security`	`XmlWinEventLog`

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: 3