Detection rules › Sigma

Lace Tempest PowerShell Evidence Eraser

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

Detects a PowerShell script used by Lace Tempest APT to erase evidence from victim servers by exploiting CVE-2023-47246 as reported by SysAid Team

Known false positives

  • Unlikely

MITRE ATT&CK coverage

Telemetry coverage

Rule body

title: Lace Tempest PowerShell Evidence Eraser
id: b377ddab-502d-4519-9e8c-5590033d2d70
status: test
description: |
    Detects a PowerShell script used by Lace Tempest APT to erase evidence from victim servers by exploiting CVE-2023-47246 as reported by SysAid Team
references:
    - https://www.sysaid.com/blog/service-desk/on-premise-software-security-vulnerability-notification
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-11-09
tags:
    - attack.execution
    - attack.t1059.001
    - detection.emerging-threats
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains|all:
            - 'cleanLL'
            - 'usersfiles.war'
            - 'Remove-Item -Path "$tomcat_dir'
            - 'SysAidServer'
            - 'sleep '
            - 'while(1)'
    condition: selection
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    ScriptBlockText|contains|all:
        - 'cleanLL'
        - 'usersfiles.war'
        - 'Remove-Item -Path "$tomcat_dir'
        - 'SysAidServer'
        - 'sleep '
        - 'while(1)'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
ScriptBlockTextmatch
  • Remove-Item -Path "$tomcat_dir
  • SysAidServer
  • cleanLL
  • sleep
  • usersfiles.war
  • while(1)
field:"ScriptBlockText" kind:match