Summary
TheSMS Admins group is a local security group created on each SMS Provider in the hierarchy. The SMS Admins local security group provides access to the SMS Provider which is a WMI provider that assigns read and write access to Configuration Manager (CM) databases.
RBAC_Admins table within the site database controls the additions and deletions to the SMS Admins local security group. That means if an account is inserted into the RBAC_Admins table, then the account’s SID is added to the SMS Admins local security group on the SMS Provider.
Attackers who relay the site server computer account to the site database server and insert a new account into the RBAC_Admins table will automatically add that user to the SMS Admins local security group.
While defenders cannot set a SACL on the local security group directly, auditing can be enabled for Object Access via auditpol.exe:
SMS Admins group for modification via Event ID: 4732. When a user is added to the RBAC_Admins table and inherently added to the SMS Admins local security group, the following Event ID: 4732 will display the following information:
RBAC_Admins table in MSSQL database server or the SMS Admins local security group, an Event ID: 4733, is generated:
SMS Admins group prior to adding the specified user via Event ID: 4799. However, this event is generated frequently by legitmate activiaty and is not directly indicative malicious additions to the local security group without the corresponding Event ID: 4799. The following displays two Event ID: 4799s in relation to the addition of a user to the SMS Admins group:
Associated Offensive IDs
- TAKEOVER-1: Hierarchy takeover via NTLM coercion and relay to MSSQL on remote site database
- TAKEOVER-2: Hierarchy takeover via NTLM coercion and relay to SMB on remote site database
- RECON-4: Query client devices via CMPivot
- RECON-5: Locate users via SMS Provider
References
- Garrett Foster, Site Takeover via SCCM’s AdminService API
- Microsoft Learn, Plan for the SMS Provider
- Microsoft Learn, 4732(S): A member was added to a security-enabled local group.