PSEXEC Remote Execution File Artefact

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

Detects creation of the PSEXEC key file. Which is created anytime a PsExec command is executed. It gets written to the file system and will be recorded in the USN Journal on the target system

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1136.002` Create Account: Domain Account `T1543.003` Create or Modify System Process: Windows Service
Privilege Escalation	`T1543.003` Create or Modify System Process: Windows Service
Lateral Movement	`T1570` Lateral Tool Transfer

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 11: FileCreate

Rule body

title: PSEXEC Remote Execution File Artefact
id: 304afd73-55a5-4bb9-8c21-0b1fc84ea9e4
status: test
description: Detects creation of the PSEXEC key file. Which is created anytime a PsExec command is executed. It gets written to the file system and will be recorded in the USN Journal on the target system
references:
    - https://aboutdfir.com/the-key-to-identify-psexec/
    - https://twitter.com/davisrichardg/status/1616518800584704028
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-01-21
modified: 2023-02-23
tags:
    - attack.lateral-movement
    - attack.privilege-escalation
    - attack.execution
    - attack.persistence
    - attack.t1136.002
    - attack.t1543.003
    - attack.t1570
    - attack.s0029
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|startswith: 'C:\Windows\PSEXEC-'
        TargetFilename|endswith: '.key'
    condition: selection
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    TargetFilename|startswith: 'C:\Windows\PSEXEC-'
    TargetFilename|endswith: '.key'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`TargetFilename`	ends_with	`.key` corpus 2 (sigma 2)	`field:"TargetFilename" kind:ends_with value:".key"`
`TargetFilename`	starts_with	`C:\Windows\PSEXEC-`	`field:"TargetFilename" kind:starts_with value:"C:\Windows\PSEXEC-"`