Suspicious Event Log Service Behavior

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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.

• Type: Hunting

• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

• Last Updated: 2024-05-14
• Author: Mauricio Velazco, Splunk
• ID: 2b85aa3d-f5f6-4c2e-a081-a09f6e1c2e40

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1070	Indicator Removal	Defense Evasion

T1070.001

Clear Windows Event Logs

Defense Evasion

Kill Chain Phase

• Exploitation

NIST

• DE.AE

CIS20

• CIS 10

CVE

Search

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

Macros

The SPL above uses the following Macros:

• security_content_ctime
• wineventlog_security

suspicious_event_log_service_behavior_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

• _time
• EventCode
• dest

How To Implement

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

• Windows Log Manipulation
• Ransomware
• Clop Ransomware

RBA

Risk Score	Impact	Confidence	Message
9.0	30	30	The Windows Event Log Service shutdown on $dest$

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

• https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-1100
• https://www.ired.team/offensive-security/defense-evasion/disabling-windows-event-logs-by-suspending-eventlog-service-threads
• https://attack.mitre.org/techniques/T1070/001/
• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1070.001/T1070.001.md

Test Dataset

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 | version: 3