Detection: Windows Snake Malware Service Create

Updated Date: 2024-05-13 ID: 64eb091f-8cab-4b41-9b09-8fb4942377df Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the creation of a new service named WerFaultSvc with a binary path in the Windows WinSxS directory. It leverages Windows System logs, specifically EventCode 7045, to identify this activity. This behavior is significant because it indicates the presence of Snake malware, which uses this service to maintain persistence by blending in with legitimate Windows services. If confirmed malicious, this activity could allow an attacker to execute Snake malware components, leading to potential data exfiltration, system compromise, and long-term persistence within the environment.

1`wineventlog_system` EventCode=7045  ImagePath="*\\windows\\winSxS\\*" ImagePath="*\Werfault.exe" 
2| stats count min(_time) as firstTime max(_time) as lastTime by Computer EventCode ImagePath ServiceName ServiceType 
3| rename Computer as dest 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_snake_malware_service_create_filter`

Data Source

Name Platform Sourcetype Source Supported App
Windows Event Log System 7045 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:System' N/A

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_snake_malware_service_create_filter search *
windows_snake_malware_service_create_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
T1547.006 Kernel Modules and Extensions Persistence
T1569.002 Service Execution Privilege Escalation
KillChainPhase.EXPLOITAITON
KillChainPhase.INSTALLATION
NistCategory.DE_CM
Cis18Value.CIS_10
APT32
APT38
APT39
APT41
Blue Mockingbird
Chimera
FIN6
Ke3chang
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 Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

To successfully implement this search, you need to be ingesting Windows System logs with the Service name, Service File Name Service Start type, and Service Type from your endpoints.

Known False Positives

False positives should be limited as this is a strict primary indicator used by Snake Malware.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A service, WerFaultSvc, was created on $dest$ and is related to Snake Malware. 72 80 90
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:System XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:System 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: 2