The following analytic identifies when either a global catalog SPN or a DRS RPC SPN are temporarily added to an Active Directory computer object, both of which can be evidence of a DCShadow attack. DCShadow allows an attacker who has obtained privileged access to register a rogue Domain Controller (DC). Once registered, the rogue DC may be able to inject and replicate changes into the AD infrastructure for any domain object, including credentials and keys. This technique was initially released in 2018 by security researchers Benjamin Delpy and Vincent Le Toux. No event logs are written for changes to AD attributes, allowing for stealthy backdoors to be implanted in the domain, or metadata such as timestamps overwritten to cover tracks.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-09-02
- Author: Dean Luxton
- ID: 57e27f27-369c-4df8-af08-e8c7ee8373d4
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 7 8 9 10 `wineventlog_security` EventCode=5136 AttributeLDAPDisplayName=servicePrincipalName (AttributeValue="GC/*" OR AttributeValue="E3514235-4B06-11D1-AB04-00C04FC2DCD2/*") | stats min(_time) as _time range(_time) as duration values(OperationType) as OperationType values(src_nt_domain) as src_nt_domain values(src_user) as src_user values(Computer) as Computer, values(ObjectDN) as ObjectDN by Logon_ID | eval short_lived=case((duration<30),"TRUE") | where short_lived="TRUE" AND mvcount(OperationType)>1 | replace "%%14674" with "Value Added", "%%14675" with "Value Deleted" in OperationType | rename Logon_ID as TargetLogonId | appendpipe [ | map search="search `wineventlog_security` EventCode=4624 TargetLogonId=$TargetLogonId$"] | stats min(_time) as _time, values(TargetUserSid) as TargetUserSid, values(Target_Domain) as Target_Domain, values(user) as user, values(Computer) as Computer, values(status) as status, values(src_category) as src_category, values(src_ip) as src_ip values(ObjectDN) as ObjectDN values(OperationType) as OperationType by TargetLogonId | `windows_ad_short_lived_domain_controller_spn_attribute_filter`
The SPL above uses the following Macros:
windows_ad_short_lived_domain_controller_spn_attribute_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
To successfully implement this search, you need to be ingesting eventcode
5136. The Advanced Security Audit policy setting
Audit Directory Services Changes within
DS Access needs to be enabled, alongside a SACL for
Write All Properties applied to the domain root and all descendant objects.
Known False Positives
Associated Analytic Story
|100.0||100||100||Short Lived Domain Controller SPN AD Attribute Triggered by $user$ from $src_ip$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 2