Detection rules › Sigma

Suspicious Windows Update Agent Empty Cmdline

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

Detects suspicious Windows Update Agent activity in which a wuauclt.exe process command line doesn't contain any command line flags

MITRE ATT&CK coverage

TacticTechniques
Stealth

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 1: Process creation

Rule body

title: Suspicious Windows Update Agent Empty Cmdline
id: 52d097e2-063e-4c9c-8fbb-855c8948d135
status: test
description: |
    Detects suspicious Windows Update Agent activity in which a wuauclt.exe process command line doesn't contain any command line flags
references:
    - https://redcanary.com/blog/blackbyte-ransomware/
author: Florian Roth (Nextron Systems)
date: 2022-02-26
modified: 2023-11-11
tags:
    - attack.stealth
    - attack.t1036
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\Wuauclt.exe'
        - OriginalFileName: 'Wuauclt.exe'
    selection_cli:
        CommandLine|endswith:
            - 'Wuauclt'
            - 'Wuauclt.exe'
    condition: all of selection*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

all of selection*

Stage 1: selection_img

selection_img:
    - Image|endswith: '\Wuauclt.exe'
    - OriginalFileName: 'Wuauclt.exe'

Stage 2: selection_cli

selection_cli:
    CommandLine|endswith:
        - 'Wuauclt'
        - 'Wuauclt.exe'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLineends_with
  • Wuauclt
  • Wuauclt.exe
field:"CommandLine" kind:ends_with
Imageends_with
  • \Wuauclt.exe corpus 3 (sigma 3)
field:"Image" kind:ends_with value:"\Wuauclt.exe"
OriginalFileNameeq
  • Wuauclt.exe corpus 5 (elastic 3, sigma 2)
field:"OriginalFileName" kind:eq value:"Wuauclt.exe"