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Detection rules › Sigma

Potential Remote Desktop Connection to Non-Domain Host

Status
test
Severity
medium
Log source
product windows, service ntlm
Author
James Pemberton
Source
github.com/SigmaHQ/sigma

Detects logons using NTLM to hosts that are potentially not part of the domain.

Known false positives

  • Host connections to valid domains, exclude these.
  • Host connections not using host FQDN.
  • Host connections to external legitimate domains.

MITRE ATT&CK coverage

TacticTechniques
Command & Control

Telemetry coverage

ProviderRecord / event type
NTLMEvent ID 8001: NTLM client blocked audit: Audit outgoing NTLM authentication traffic that would be blocked.

Rule body

title: Potential Remote Desktop Connection to Non-Domain Host
id: ce5678bb-b9aa-4fb5-be4b-e57f686256ad
status: test
description: Detects logons using NTLM to hosts that are potentially not part of the domain.
references:
    - n/a
author: James Pemberton
date: 2020-05-22
modified: 2021-11-27
tags:
    - attack.command-and-control
    - attack.t1219.002
logsource:
    product: windows
    service: ntlm
    definition: Requires events from Microsoft-Windows-NTLM/Operational
detection:
    selection:
        EventID: 8001
        TargetName|startswith: 'TERMSRV'
    condition: selection
falsepositives:
    - Host connections to valid domains, exclude these.
    - Host connections not using host FQDN.
    - Host connections to external legitimate domains.
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    EventID: 8001
    TargetName|startswith: 'TERMSRV'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
TargetNamestarts_with
  • TERMSRV
field:"TargetName" kind:starts_with value:"TERMSRV"