Detection rules › Sigma

Renamed Plink Execution

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

Detects the execution of a renamed version of the Plink binary

MITRE ATT&CK coverage

TacticTechniques
Stealth

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 1: Process creation

Rule body

title: Renamed Plink Execution
id: 1c12727d-02bf-45ff-a9f3-d49806a3cf43
status: test
description: Detects the execution of a renamed version of the Plink binary
references:
    - https://thedfirreport.com/2022/06/06/will-the-real-msiexec-please-stand-up-exploit-leads-to-data-exfiltration/
    - https://the.earth.li/~sgtatham/putty/0.58/htmldoc/Chapter7.html
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-06-06
modified: 2023-02-03
tags:
    - attack.stealth
    - attack.t1036
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - OriginalFileName: 'Plink'
        - CommandLine|contains|all:
              - ' -l forward'
              - ' -P '
              - ' -R '
    filter:
        Image|endswith: '\plink.exe'
    condition: selection and not filter
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection and not filter

Stage 1: selection

selection:
    - OriginalFileName: 'Plink'
    - CommandLine|contains|all:
          - ' -l forward'
          - ' -P '
          - ' -R '

Stage 2: not filter

filter:
    Image|endswith: '\plink.exe'

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
Imageends_with\plink.exeexcludes:Image field:"Image" value:"\plink.exe"

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • -P corpus 11 (sigma 7, splunk 4)
  • -R corpus 10 (sigma 10)
  • -l forward
field:"CommandLine" kind:match
OriginalFileNameeq
  • Plink corpus 3 (sigma 1, elastic 1, splunk 1)
field:"OriginalFileName" kind:eq value:"Plink"