PsExec/PAExec Escalation to LOCAL SYSTEM — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2021-11-23 / 2024-03-05.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: e7a596ddd361c9fb5c60b824f7b4344ea16d49c21f2577bc5bd28e5e6c474b23

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: PsExec/PAExec Escalation to LOCAL SYSTEM
id: 8834e2f7-6b4b-4f09-8906-d2276470ee23
related:
    - id: 207b0396-3689-42d9-8399-4222658efc99 # Generic rule based on similar cli flags
      type: similar
status: test
description: Detects suspicious commandline flags used by PsExec and PAExec to escalate a command line to LOCAL_SYSTEM rights
references:
    - https://learn.microsoft.com/en-us/sysinternals/downloads/psexec
    - https://www.poweradmin.com/paexec/
    - https://www.fireeye.com/blog/threat-research/2020/10/kegtap-and-singlemalt-with-a-ransomware-chaser.html
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2021-11-23
modified: 2024-03-05
tags:
    - attack.resource-development
    - attack.t1587.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_sys: # Escalation to LOCAL_SYSTEM
        CommandLine|contains|windash:
            # Note that you don't need to add the ".exe" part when using psexec/paexec
            # The "-" can also be replaced with "/"
            # The order of args isn't important
            # "cmd" can be replaced by "powershell", "pwsh" or any other console like software
            - ' -s cmd'
            - ' -s -i cmd'
            - ' -i -s cmd'
            # Pwsh (For PowerShell 7)
            - ' -s pwsh'
            - ' -s -i pwsh'
            - ' -i -s pwsh'
            # PowerShell (For PowerShell 5)
            - ' -s powershell'
            - ' -s -i powershell'
            - ' -i -s powershell'
    selection_other:
        CommandLine|contains:
            - 'psexec'
            - 'paexec'
            - 'accepteula'
    condition: all of selection_*
falsepositives:
    - Admins that use PsExec or PAExec to escalate to the SYSTEM account for maintenance purposes (rare)
    - Users that debug Microsoft Intune issues using the commands mentioned in the official documentation; see https://learn.microsoft.com/en-us/mem/intune/apps/intune-management-extension
level: high

Original YAML and metadata in JSON

False positives

• Admins that use PsExec or PAExec to escalate to the SYSTEM account for maintenance purposes (rare)
• Users that debug Microsoft Intune issues using the commands mentioned in the official documentation; see https://learn.microsoft.com/en-us/mem/intune/apps/intune-management-extension

Source references

• https://learn.microsoft.com/en-us/sysinternals/downloads/psexec
• https://www.poweradmin.com/paexec/
• https://www.fireeye.com/blog/threat-research/2020/10/kegtap-and-singlemalt-with-a-ransomware-chaser.html