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https://github.com/splunk/security_content
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pyth0n1c
87 lines
4.4 KiB
YAML
87 lines
4.4 KiB
YAML
name: Windows AD Self DACL Assignment
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id: 16132445-da9f-4d03-ad44-56d717dcd67d
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version: 1
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date: '2023-12-18'
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author: Dean Luxton
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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: Detect when a user creates a new DACL in AD for their own AD object.
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search: '`wineventlog_security` EventCode=5136 | stats min(_time) as _time values(eval(if(OperationType=="%%14675",AttributeValue,null)))
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as old_value values(eval(if(OperationType=="%%14674",AttributeValue,null))) as new_value
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values(OperationType) as OperationType by ObjectClass ObjectDN OpCorrelationID src_user
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SubjectLogonId | rex field=old_value max_match=10000 "\((?P<old_values>.*?)\)" |
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rex field=new_value max_match=10000 "\((?P<new_ace>.*?)\)" | mvexpand new_ace |
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where NOT new_ace IN (old_values) | rex field=new_ace "(?P<aceType>.*?);(?P<aceFlags>.*?);(?P<aceAccessRights>.*?);(?P<aceObjectGuid>.*?);(?P<aceInheritedTypeGuid>.*?);(?P<aceSid>.*?)$" |
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rex max_match=100 field=aceAccessRights "(?P<AccessRights>[A-Z]{2})" | rex max_match=100
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field=aceFlags "(?P<aceFlags>[A-Z]{2})" | lookup ace_type_lookup ace_type_string
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as aceType OUTPUT ace_type_value as aceType | lookup ace_flag_lookup flag_string
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as aceFlags OUTPUT flag_value as ace_flag_value | lookup ace_access_rights_lookup
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access_rights_string as AccessRights OUTPUT access_rights_value | lookup msad_guid_lookup
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guid as aceObjectGuid OUTPUT displayName as ControlAccessRights ``` Optional SID
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resolution lookups | lookup identity_lookup_expanded objectSid as aceSid OUTPUT
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downLevelDomainName as user | lookup admon_groups_def objectSid as aceSid OUTPUT
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cn as group ``` | lookup builtin_groups_lookup builtin_group_string as aceSid OUTPUT
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builtin_group_name as builtin_group | eval aceType=coalesce(ace_type_value,aceType),
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aceInheritance=coalesce(ace_flag_value,"This object only"), aceAccessRights=if(aceAccessRights="CCDCLCSWRPWPDTLOCRSDRCWDWO","Full
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control",coalesce(access_rights_value,AccessRights)), aceControlAccessRights=if((ControlAccessRights="Write
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member" OR aceObjectGuid="bf9679c0-0de6-11d0-a285-00aa003049e2") AND (aceAccessRights="All
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validated writes" OR AccessRights="SW"),"Add/remove self as member",coalesce(ControlAccessRights,aceObjectGuid)),
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user=coalesce(user, group, builtin_group, aceSid) | stats values(aceType) as aceType
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values(aceInheritance) as aceInheritance values(aceControlAccessRights) as aceControlAccessRights
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values(aceAccessRights) as aceAccessRights values(new_ace) as new_ace values(aceInheritedTypeGuid)
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as aceInheritedTypeGuid by _time ObjectClass ObjectDN src_user SubjectLogonId user
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OpCorrelationID | eval aceControlAccessRights=if(mvcount(aceControlAccessRights)=1
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AND aceControlAccessRights="","All rights",''aceControlAccessRights'') | rex field=user
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"\\\(?P<nt_user>.*?)$" | where lower(src_user)=lower(nt_user) | `windows_ad_self_dacl_assignment_filter`'
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how_to_implement: Ensure you are ingesting Active Directory audit logs - specifically
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event 5136. See lantern article in references for further on how to onboard AD audit
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data. Ensure the wineventlog_security macro is configured with the correct indexes
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and include lookups for SID resolution if evt_resolve_ad_obj is set to 0.
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known_false_positives: Unknown
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references:
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- https://lantern.splunk.com/Security/Product_Tips/Enterprise_Security/Enabling_an_audit_trail_from_Active_Directory
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drilldown_searches:
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- name: View the detection results for $src_user$
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search: '%original_detection_search% | search src_user = $src_user$'
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tags:
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analytic_story:
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- Sneaky Active Directory Persistence Tricks
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asset_type: Endpoint
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confidence: 100
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impact: 80
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message: $src_user$ has created a DACL on $ObjectDN$ to grant themselves $aceControlAccessRights$
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across $aceAccessRights$
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mitre_attack_id:
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- T1484
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- T1098
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observable:
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- name: src_user
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type: User
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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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risk_score: 80
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required_fields:
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- _time
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- OperationType
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- ObjectDN
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- OpCorrelationID
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- src_user
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- AttributeLDAPDisplayName
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- AttributeValue
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- ObjectClass
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- SubjectLogonId
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- DSName
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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/aclmodification/windows-security-xml.log
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source: XmlWinEventLog:Security
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sourcetype: xmlwineventlog
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