Metasploit Or Impacket Service Installation Via SMB PsExec

Status: test
Severity: high
Log source: product windows, service security
Author: Bartlomiej Czyz, Relativity
Source: github.com/SigmaHQ/sigma

Detects usage of Metasploit SMB PsExec (exploit/windows/smb/psexec) and Impacket psexec.py by triggering on specific service installation

Known false positives

Possible, different agents with a 8 character binary and a 4, 8 or 16 character service name

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1569.002` System Services: Service Execution
Lateral Movement	`T1021.002` Remote Services: SMB/Windows Admin Shares `T1570` Lateral Tool Transfer

Telemetry coverage

Provider	Record / event type
Security-Auditing	Event ID 4697: A service was installed in the system.

Rule body

title: Metasploit Or Impacket Service Installation Via SMB PsExec
id: 6fb63b40-e02a-403e-9ffd-3bcc1d749442
related:
    - id: 1a17ce75-ff0d-4f02-9709-2b7bb5618cf0
      type: derived
status: test
description: Detects usage of Metasploit SMB PsExec (exploit/windows/smb/psexec) and Impacket psexec.py by triggering on specific service installation
references:
    - https://bczyz1.github.io/2021/01/30/psexec.html
author: Bartlomiej Czyz, Relativity
date: 2021-01-21
modified: 2022-10-05
tags:
    - attack.lateral-movement
    - attack.t1021.002
    - attack.t1570
    - attack.execution
    - attack.t1569.002
logsource:
    product: windows
    service: security
    definition: The 'System Security Extension' audit subcategory need to be enabled to log the EID 4697
detection:
    selection:
        EventID: 4697
        ServiceFileName|re: '^%systemroot%\\[a-zA-Z]{8}\.exe$'
        ServiceName|re: '(^[a-zA-Z]{4}$)|(^[a-zA-Z]{8}$)|(^[a-zA-Z]{16}$)'
        ServiceStartType: 3  # on-demand start, see https://www.ultimatewindowssecurity.com/securitylog/encyclopedia/event.aspx?eventID=4697
        ServiceType: '0x10'
    filter:
        ServiceName: 'PSEXESVC'
    condition: selection and not filter
falsepositives:
    - Possible, different agents with a 8 character binary and a 4, 8 or 16 character service name
level: high

Stages and Predicates

Stage 0: `condition`

selection and not filter

Stage 1: `selection`

selection:
    EventID: 4697
    ServiceFileName|re: '^%systemroot%\\[a-zA-Z]{8}\.exe$'
    ServiceName|re: '(^[a-zA-Z]{4}$)|(^[a-zA-Z]{8}$)|(^[a-zA-Z]{16}$)'
    ServiceStartType: 3
    ServiceType: '0x10'

Stage 2: `not filter`

filter:
    ServiceName: 'PSEXESVC'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`ServiceName`	eq	`PSEXESVC`	`excludes:ServiceName` `field:"ServiceName" value:"PSEXESVC"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ServiceFileName`	regex_match	`^%systemroot%\[a-zA-Z]{8}.exe$`	`field:"ServiceFileName" kind:regex_match value:"^%systemroot%\[a-zA-Z]{8}.exe$"`
`ServiceName`	regex_match	`(^[a-zA-Z]{4}$)` `(^[a-zA-Z]{8}$)` `(^[a-zA-Z]{16}$)`	`field:"ServiceName" kind:regex_match`
`ServiceStartType`	eq	`3`	`field:"ServiceStartType" kind:eq value:"3"`
`ServiceType`	eq	`0x10`	`field:"ServiceType" kind:eq value:"0x10"`