Potential SNAKE Malware Persistence Service Execution

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects a specific child/parent process relationship indicative of a "WerFault" process running from the "WinSxS" as a service. This could be indicative of potential SNAKE malware activity as reported by CISA.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	No specific technique

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation
Security-Auditing	Event ID 4688: A new process has been created.

Rule body

title: Potential SNAKE Malware Persistence Service Execution
id: f7536642-4a08-4dd9-b6d5-c3286d8975ed
status: test
description: Detects a specific child/parent process relationship indicative of a "WerFault" process running from the "WinSxS" as a service. This could be indicative of potential SNAKE malware activity as reported by CISA.
references:
    - https://media.defense.gov/2023/May/09/2003218554/-1/-1/0/JOINT_CSA_HUNTING_RU_INTEL_SNAKE_MALWARE_20230509.PDF
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-05-04
tags:
    - attack.execution
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\services.exe'
        Image|startswith: 'C:\Windows\WinSxS\'
        Image|endswith: '\WerFault.exe'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    ParentImage|endswith: '\services.exe'
    Image|startswith: 'C:\Windows\WinSxS\'
    Image|endswith: '\WerFault.exe'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Image`	ends_with	`\WerFault.exe` corpus 8 (sigma 8)	`field:"Image" kind:ends_with value:"\WerFault.exe"`
`Image`	starts_with	`C:\Windows\WinSxS\`	`field:"Image" kind:starts_with value:"C:\Windows\WinSxS\"`
`ParentImage`	ends_with	`\services.exe` corpus 8 (sigma 8)	`field:"ParentImage" kind:ends_with value:"\services.exe"`