Detection rules › Sigma

NTLM Brute Force

Status
test
Severity
medium
Log source
product windows, service ntlm
Author
Jerry Shockley '@jsh0x'
Source
github.com/SigmaHQ/sigma

Detects common NTLM brute force device names

MITRE ATT&CK coverage

TacticTechniques
Credential AccessT1110 Brute Force

Rule body yaml

title: NTLM Brute Force
id: 9c8acf1a-cbf9-4db6-b63c-74baabe03e59
status: test
description: Detects common NTLM brute force device names
references:
    - https://www.varonis.com/blog/investigate-ntlm-brute-force
author: Jerry Shockley '@jsh0x'
date: 2022-02-02
tags:
    - attack.credential-access
    - attack.t1110
logsource:
    product: windows
    service: ntlm
    definition: Requires events from Microsoft-Windows-NTLM/Operational
detection:
    selection:
        EventID: 8004
    devicename:
        WorkstationName:
            - 'Rdesktop'
            - 'Remmina'
            - 'Freerdp'
            - 'Windows7'
            - 'Windows8'
            - 'Windows2012'
            - 'Windows2016'
            - 'Windows2019'
    condition: selection and devicename
falsepositives:
    - Systems with names equal to the spoofed ones used by the brute force tools
level: medium

Stages and Predicates

Stage 0: condition

selection and devicename

Stage 1: selection

selection:
    EventID: 8004

Stage 2: devicename

devicename:
    WorkstationName:
        - 'Rdesktop'
        - 'Remmina'
        - 'Freerdp'
        - 'Windows7'
        - 'Windows8'
        - 'Windows2012'
        - 'Windows2016'
        - 'Windows2019'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
WorkstationNameeq
  • Freerdp
  • Rdesktop
  • Remmina
  • Windows2012
  • Windows2016
  • Windows2019
  • Windows7
  • Windows8