PSexec execution over SMB share

Status: experimental
Severity: medium
Log source: product windows, service security
Author: mdecrevoisier
Source: github.com/mdecrevoisier/SIGMA-detection-rules

Detects scenarios where an attacker execute PSexec on a remote host via SMB

Known false positives

Administrator activity

MITRE ATT&CK coverage

Tactic	Techniques
Lateral Movement	`T1021.002` Remote Services: SMB/Windows Admin Shares

Telemetry coverage

Provider	Record / event type
Security-Auditing	Event ID 5145: A network share object was checked to see whether client can be granted desired access.

Rule body

title: PSexec execution over SMB share
description: Detects scenarios where an attacker execute PSexec on a remote host via SMB
references:
- https://github.com/mdecrevoisier/EVTX-to-MITRE-Attack/tree/master/TA0008-Lateral%20Movement/T1021.002%20-SMB%20Windows%20Admin%20Shares
- https://attack.mitre.org/software/S0029/
- https://pentera.io/blog/135-is-the-new-145/
- https://nv2lt.github.io/windows/smb-psexec-smbexec-winexe-how-to/
- https://www.synacktiv.com/publications/traces-of-windows-remote-command-execution.html
tags:
- attack.lateral_movement
- attack.t1021.002
author: mdecrevoisier
status: experimental
logsource:
  product: windows
  service: security
detection:
  selection:
    EventID: 5145
    ShareName:
      - '\\*\ADMIN$'
      - '\\*\IPC$'
    RelativeTargetName|contains: PSEXESVC
  filter:
    SubjectUserName: '%admin_account%'
  condition: selection and not filter
falsepositives:
- Administrator activity
level: medium

Stages and Predicates

Stage 0: `condition`

selection and not filter

Stage 1: `selection`

selection:
  EventID: 5145
  ShareName:
    - '\\*\ADMIN$'
    - '\\*\IPC$'
  RelativeTargetName|contains: PSEXESVC

Stage 2: `not filter`

filter:
  SubjectUserName: '%admin_account%'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`SubjectUserName`	eq	`%admin_account%`	`excludes:SubjectUserName` `field:"SubjectUserName" value:"%admin_account%"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`RelativeTargetName`	match	`PSEXESVC`	`field:"RelativeTargetName" kind:match value:"PSEXESVC"`
`ShareName`	wildcard	`\\\ADMIN$` corpus 6 (sigma 6) `\\\IPC$` corpus 11 (sigma 11)	`field:"ShareName" kind:wildcard`

PSexec execution over SMB share

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter`