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tccontre
79 lines
3.3 KiB
YAML
79 lines
3.3 KiB
YAML
name: Windows Default Group Policy Object Modified
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id: fe6a6cc4-9e0d-4d66-bcf4-2c7f44860876
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version: 1
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date: '2023-03-28'
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author: Mauricio Velazco, Splunk
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status: production
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type: TTP
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data_source:
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- Windows Security 5136
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description: The following analytic leverages Event ID 5136 to identify the modification
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of a default Group Policy Object. A fresh installation of an Active Directory network
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will typically contain two default group policy objects `Default Domain Controllers
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Policy` and `Default Domain Policy`. The default domain controllers policy is used
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to enforce and set policies to all the domain controllers within the domain environment.
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The default domain policy is linked to all users and computers by default. An adversary
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who has obtained privileged access to an Active Directory network may modify the
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default group policy objects to obtain further access, deploy persistence or execute
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malware across a large number of hosts. Security teams should monitor the modification
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of the default GPOs.
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search: ' `wineventlog_security` EventCode=5136 ObjectClass=groupPolicyContainer AttributeLDAPDisplayName=versionNumber
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(ObjectDN="CN={31B2F340-016D-11D2-945F-00C04FB984F9},CN=POLICIES,CN=SYSTEM,DC=*"
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OR ObjectDN="CN={6AC1786C-016F-11D2-945F-00C04fB984F9},CN=POLICIES,CN=SYSTEM,DC=*")
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| stats min(_time) as firstTime max(_time) as lastTime by ObjectDN SubjectUserSid
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AttributeValue Computer DSName | rename AttributeValue as versionNumber | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)` | `windows_default_group_policy_object_modified_filter`'
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how_to_implement: To successfully implement this search, the Advanced Security Audit
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policy setting `Audit Directory Service Changes` within `DS Access` needs to be
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enabled. Furthermore, the appropriate system access control lists (SACL) need to
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be created as the used events are not logged by default. A good guide to accomplish
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this can be found here https://jgspiers.com/audit-group-policy-changes/.
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known_false_positives: The default Group Policy Objects within an AD network may be
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legitimately updated for administrative operations, filter as needed.
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references:
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- https://attack.mitre.org/techniques/T1484/
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- https://attack.mitre.org/techniques/T1484/001
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- https://www.trustedsec.com/blog/weaponizing-group-policy-objects-access/
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- https://adsecurity.org/?p=2716
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tags:
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analytic_story:
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- Active Directory Privilege Escalation
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- Sneaky Active Directory Persistence Tricks
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asset_type: Endpoint
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confidence: 50
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impact: 100
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message: A default group policy object was modified on $Computer$ by $SubjectUserSid$
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mitre_attack_id:
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- T1484
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- T1484.001
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observable:
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- name: SubjectUserSid
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type: User
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role:
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- Attacker
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- name: Computer
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type: Endpoint
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role:
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- Victim
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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required_fields:
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- EventCode
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- ObjectClass
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- AttributeLDAPDisplayName
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- ObjectDN
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- Computer
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- DSName
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- AttributeValue
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- SubjectUserSid
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risk_score: 50
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security_domain: endpoint
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tests:
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- name: True Positive Test
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attack_data:
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- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1484.001/default_domain_policy_modified/windows-security.log
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source: XmlWinEventLog:Security
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sourcetype: XmlWinEventLog
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