Detection rules › Sigma

Possible DC Shadow Attack

Status
test
Severity
medium
Log source
product windows, service security
Author
Ilyas Ochkov, oscd.community, Chakib Gzenayi (@Chak092), Hosni Mribah
Source
github.com/SigmaHQ/sigma

Detects DCShadow via create new SPN

MITRE ATT&CK coverage

TacticTechniques
Defense ImpairmentT1207 Rogue Domain Controller

Event coverage

Rule body yaml

title: Possible DC Shadow Attack
id: 32e19d25-4aed-4860-a55a-be99cb0bf7ed
related:
    - id: 611eab06-a145-4dfa-a295-3ccc5c20f59a
      type: derived
status: test
description: Detects DCShadow via create new SPN
references:
    - https://twitter.com/gentilkiwi/status/1003236624925413376
    - https://gist.github.com/gentilkiwi/dcc132457408cf11ad2061340dcb53c2
    - https://web.archive.org/web/20180203014709/https://blog.alsid.eu/dcshadow-explained-4510f52fc19d?gi=c426ac876c48
author: Ilyas Ochkov, oscd.community, Chakib Gzenayi (@Chak092), Hosni Mribah
date: 2019-10-25
modified: 2022-10-17
tags:
    - attack.credential-access
    - attack.defense-impairment
    - attack.t1207
logsource:
    product: windows
    service: security
    definition: The "Audit Directory Service Changes" logging policy must be configured in order to receive events. Audit events are generated only for objects with configured system access control lists (SACLs). Audit events are generated only for objects with configured system access control lists (SACLs) and only when accessed in a manner that matches their SACL settings. This policy covers the following events ids - 5136, 5137, 5138, 5139, 5141. Note that the default policy does not cover User objects. For that a custom AuditRule need to be setup (See https://github.com/OTRF/Set-AuditRule)
detection:
    selection1:
        EventID: 4742
        ServicePrincipalNames|contains: 'GC/'
    selection2:
        EventID: 5136
        AttributeLDAPDisplayName: servicePrincipalName
        AttributeValue|startswith: 'GC/'
    condition: 1 of selection*
falsepositives:
    - Valid on domain controllers; exclude known DCs
level: medium

Stages and Predicates

Stage 0: condition

1 of selection*

Stage 1: selection1

selection1:
    EventID: 4742
    ServicePrincipalNames|contains: 'GC/'

Stage 2: selection2

selection2:
    EventID: 5136
    AttributeLDAPDisplayName: servicePrincipalName
    AttributeValue|startswith: 'GC/'

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
AttributeLDAPDisplayNameeq
  • servicePrincipalName corpus 9 (sigma 4, splunk 3, elastic 1, kusto 1)
AttributeValuestarts_with
  • GC/ corpus 2 (sigma 2)
ServicePrincipalNamesmatch
  • GC/ corpus 2 (sigma 2)