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Detection rules › Sigma

ADCS Certificate Template Configuration Vulnerability with Risky EKU

Status
test
Severity
high
Log source
product windows, service security
Author
Orlinum , BlueDefenZer
Source
github.com/SigmaHQ/sigma

Detects certificate creation with template allowing risk permission subject and risky EKU

Known false positives

  • Administrator activity
  • Proxy SSL certificate with subject modification
  • Smart card enrollement

MITRE ATT&CK coverage

TacticTechniques
Privilege EscalationNo specific technique
Credential AccessNo specific technique

Telemetry coverage

ProviderRecord / event type
Security-AuditingEvent ID 4898: Certificate Services loaded a template.
Security-AuditingEvent ID 4899: A Certificate Services template was updated.

Rule body

title: ADCS Certificate Template Configuration Vulnerability with Risky EKU
id: bfbd3291-de87-4b7c-88a2-d6a5deb28668
status: test
description: Detects certificate creation with template allowing risk permission subject and risky EKU
references:
    - https://www.specterops.io/assets/resources/Certified_Pre-Owned.pdf
author: Orlinum , BlueDefenZer
date: 2021-11-17
modified: 2022-12-25
tags:
    - attack.privilege-escalation
    - attack.credential-access
logsource:
    product: windows
    service: security
    definition: Certificate services loaded a template would trigger event ID 4898 and certificate Services template was updated would trigger event ID 4899. A risk permission seems to be coming if template contain specific flag with risky EKU.
detection:
    selection10:
        EventID: 4898
        TemplateContent|contains:
            - '1.3.6.1.5.5.7.3.2'
            - '1.3.6.1.5.2.3.4'
            - '1.3.6.1.4.1.311.20.2.2'
            - '2.5.29.37.0'
    selection11:
        TemplateContent|contains: 'CT_FLAG_ENROLLEE_SUPPLIES_SUBJECT'

    selection20:
        EventID: 4899
        NewTemplateContent|contains:
            - '1.3.6.1.5.5.7.3.2'
            - '1.3.6.1.5.2.3.4'
            - '1.3.6.1.4.1.311.20.2.2'
            - '2.5.29.37.0'
    selection21:
        NewTemplateContent|contains: 'CT_FLAG_ENROLLEE_SUPPLIES_SUBJECT'

    condition: (selection10 and selection11) or (selection20 and selection21)
falsepositives:
    - Administrator activity
    - Proxy SSL certificate with subject modification
    - Smart card enrollement
level: high

Stages and Predicates

Stage 0: condition

(selection10 and selection11) or (selection20 and selection21)

Stage 1: selection10

selection10:
    EventID: 4898
    TemplateContent|contains:
        - '1.3.6.1.5.5.7.3.2'
        - '1.3.6.1.5.2.3.4'
        - '1.3.6.1.4.1.311.20.2.2'
        - '2.5.29.37.0'

Stage 2: selection11

selection11:
    TemplateContent|contains: 'CT_FLAG_ENROLLEE_SUPPLIES_SUBJECT'

Stage 3: selection20

selection20:
    EventID: 4899
    NewTemplateContent|contains:
        - '1.3.6.1.5.5.7.3.2'
        - '1.3.6.1.5.2.3.4'
        - '1.3.6.1.4.1.311.20.2.2'
        - '2.5.29.37.0'

Stage 4: selection21

selection21:
    NewTemplateContent|contains: 'CT_FLAG_ENROLLEE_SUPPLIES_SUBJECT'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
NewTemplateContentmatch
  • 1.3.6.1.4.1.311.20.2.2
  • 1.3.6.1.5.2.3.4
  • 1.3.6.1.5.5.7.3.2
  • 2.5.29.37.0
  • CT_FLAG_ENROLLEE_SUPPLIES_SUBJECT corpus 2 (sigma 2)
field:"NewTemplateContent" kind:match
TemplateContentmatch
  • 1.3.6.1.4.1.311.20.2.2
  • 1.3.6.1.5.2.3.4
  • 1.3.6.1.5.5.7.3.2
  • 2.5.29.37.0
  • CT_FLAG_ENROLLEE_SUPPLIES_SUBJECT corpus 2 (sigma 2)
field:"TemplateContent" kind:match