[metadata]
creation_date = "2022/01/26"
maturity = "production"
updated_date = "2022/04/13"

[rule]
author = ["Elastic"]
description = """
Identify the modification of the msDS-KeyCredentialLink attribute in an Active Directory Computer or User Object.
Attackers can abuse control over the object and create a key pair, append to raw public key in the attribute, and obtain
persistent and stealthy access to the target user or computer object.
"""
false_positives = [
    """
    Modifications in the msDS-KeyCredentialLink attribute can be done legitimately by the Azure AD Connect
    synchronization account or the ADFS service account. These accounts can be added as Exceptions.
    """,
]
from = "now-9m"
index = ["winlogbeat-*", "logs-system.*"]
language = "kuery"
license = "Elastic License v2"
name = "Potential Shadow Credentials added to AD Object"
note = """## Setup

The 'Audit Directory Service Changes' logging policy must be configured for (Success, Failure).
Steps to implement the logging policy with Advanced Audit Configuration:

```
Computer Configuration >
Policies >
Windows Settings >
Security Settings >
Advanced Audit Policies Configuration >
Audit Policies >
DS Access >
Audit Directory Service Changes (Success,Failure)
```

The above policy does not cover User objects, so we need to set up an AuditRule using https://github.com/OTRF/Set-AuditRule.
As this specifies the msDS-KeyCredentialLink Attribute GUID, it is expected to be low noise.

```
Set-AuditRule -AdObjectPath 'AD:\\CN=Users,DC=Domain,DC=com' -WellKnownSidType WorldSid -Rights WriteProperty -InheritanceFlags Children -AttributeGUID 5b47d60f-6090-40b2-9f37-2a4de88f3063 -AuditFlags Success
```
"""
references = [
    "https://posts.specterops.io/shadow-credentials-abusing-key-trust-account-mapping-for-takeover-8ee1a53566ab",
    "https://www.thehacker.recipes/ad/movement/kerberos/shadow-credentials",
    "https://github.com/OTRF/Set-AuditRule",
]
risk_score = 73
rule_id = "79f97b31-480e-4e63-a7f4-ede42bf2c6de"
severity = "high"
tags = ["Elastic", "Host", "Windows", "Threat Detection", "Credential Access", "Active Directory"]
timestamp_override = "event.ingested"
type = "query"

query = '''
event.action:"Directory Service Changes" and event.code:"5136" and winlog.event_data.AttributeLDAPDisplayName:"msDS-KeyCredentialLink"
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
name = "Modify Authentication Process"
id = "T1556"
reference = "https://attack.mitre.org/techniques/T1556/"


[rule.threat.tactic]
name = "Credential Access"
id = "TA0006"
reference = "https://attack.mitre.org/tactics/TA0006/"