Detection rules › Sigma

Use of W32tm as Timer

Status
test
Severity
high
Log source
category process_creation, product windows
Author
frack113
Source
github.com/SigmaHQ/sigma

When configured with suitable command line arguments, w32tm can act as a delay mechanism

Known false positives

  • Legitimate use

MITRE ATT&CK coverage

TacticTechniques
Discovery

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 1: Process creation

Rule body

title: Use of W32tm as Timer
id: 6da2c9f5-7c53-401b-aacb-92c040ce1215
status: test
description: When configured with suitable command line arguments, w32tm can act as a delay mechanism
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/d0dad62dbcae9c60c519368e82c196a3db577055/atomics/T1124/T1124.md
    - https://blogs.blackberry.com/en/2022/05/dirty-deeds-done-dirt-cheap-russian-rat-offers-backdoor-bargains
author: frack113
date: 2022-09-25
tags:
    - attack.discovery
    - attack.t1124
logsource:
    category: process_creation
    product: windows
detection:
    selection_w32tm:
        - Image|endswith: '\w32tm.exe'
        - OriginalFileName: 'w32time.dll'
    selection_cmd:
        CommandLine|contains|all:
            - '/stripchart'
            - '/computer:'
            - '/period:'
            - '/dataonly'
            - '/samples:'
    condition: all of selection_*
falsepositives:
    - Legitimate use
level: high

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_w32tm

selection_w32tm:
    - Image|endswith: '\w32tm.exe'
    - OriginalFileName: 'w32time.dll'

Stage 2: selection_cmd

selection_cmd:
    CommandLine|contains|all:
        - '/stripchart'
        - '/computer:'
        - '/period:'
        - '/dataonly'
        - '/samples:'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • /computer: corpus 2 (sigma 1, splunk 1)
  • /dataonly
  • /period:
  • /samples:
  • /stripchart
field:"CommandLine" kind:match
Imageends_with
  • \w32tm.exe corpus 2 (sigma 2)
field:"Image" kind:ends_with value:"\w32tm.exe"
OriginalFileNameeq
  • w32time.dll
field:"OriginalFileName" kind:eq value:"w32time.dll"