Detection: Excessive Usage Of SC Service Utility

Updated Date: 2024-09-30 ID: cb6b339e-d4c6-11eb-a026-acde48001122 Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects excessive usage of the sc.exe service utility on a host machine. It leverages Sysmon EventCode 1 logs to identify instances where sc.exe is executed more frequently than normal within a 15-minute window. This behavior is significant as it is commonly associated with ransomware, cryptocurrency miners, and other malware attempting to create, modify, delete, or disable services, potentially related to security applications or for privilege escalation. If confirmed malicious, this activity could allow attackers to manipulate critical services, leading to system compromise or disruption of security defenses.

 1`sysmon` EventCode = 1 process_name = "sc.exe" 
 2|  bucket _time span=15m 
 3| stats values(process) as process count as numScExe by dest, _time 
 4|  eventstats avg(numScExe) as avgScExe, stdev(numScExe) as stdScExe, count as numSlots by dest 
 5|  eval upperThreshold=(avgScExe + stdScExe *3) 
 6|  eval isOutlier=if(avgScExe > 5 and avgScExe >= upperThreshold, 1, 0) 
 7|  search isOutlier=1 
 8| `security_content_ctime(firstTime)` 
 9| `security_content_ctime(lastTime)` 
10| `excessive_usage_of_sc_service_utility_filter`

Data Source

Name Platform Sourcetype Source
CrowdStrike ProcessRollup2 N/A 'crowdstrike:events:sensor' 'crowdstrike'
Sysmon EventID 1 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
excessive_usage_of_sc_service_utility_filter search *
excessive_usage_of_sc_service_utility_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
T1569 System Services Execution
T1569.002 Service Execution Execution
KillChainPhase.INSTALLATION
NistCategory.DE_AE
Cis18Value.CIS_10
TeamTNT
APT32
APT38
APT39
APT41
Blue Mockingbird
Chimera
FIN6
INC Ransom
Ke3chang
Moonstone Sleet
Silence
Wizard 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 True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances where renamed taskkill.exe may be used.

Known False Positives

excessive execution of sc.exe is quite suspicious since it can modify or execute app in high privilege permission.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Excessive Usage Of SC Service Utility 25 50 50
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:Microsoft-Windows-Sysmon/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational 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