Forum Discussion
Using gMSA with ATP results in many 2947 events
Read this:
https://docs.microsoft.com/en-us/defender-for-identity/directory-service-accounts
For better understanding how to configure it correctly.
- AndrePKIMay 18, 2022Iron Contributor
EliOfek We have the same issue. All is set up correctly. We only have gMSA but we have multiple forests. For every doamin we have a gMSA. This has logon-as-a-service on the DC and the gMSA is installed on the respective DC. Also, the PrincipalsAllowedToRetrieveManagedPassword for the gMSA contains a universal group of which the DC is a member.
Yet, we see a lot of 2947 events. The log shows
2022-05-18 10:30:01.8472 Info RemoteImpersonationManager GetGroupManagedServiceAccountTokenAsync finished [UserName=gMSAxxxx$ Domain=forest1.local IsSuccess=False] 2022-05-18 10:30:01.8472 Info RemoteImpersonationManager CreateImpersonatorInternalAsync finished [UserName=gMSAxxxx$ Domain=forest1.local] 2022-05-18 10:30:01.8472 Warn DirectoryServicesClient CreateLdapConnectionAsync failed to retrieve group managed service account password. [DomainControllerDnsName=unix.local Domain=forest1.local UserName=gMSAxxxx$ ] 2022-05-18 10:30:01.8472 Info RemoteImpersonationManager CreateImpersonatorInternalAsync started [UserName=gMSAxxxx$ Domain=forest2chld.local IsGroupManagedServiceAccount=True] 2022-05-18 10:30:02.5503 Info RemoteImpersonationManager GetGroupManagedServiceAccountTokenAsync finished [UserName=gMSAxxxx$ Domain=forest2chld.local IsSuccess=False] 2022-05-18 10:30:02.5503 Info RemoteImpersonationManager CreateImpersonatorInternalAsync finished [UserName=GMSY000001$ Domain=forest2chld.local] 2022-05-18 10:30:02.5503 Warn DirectoryServicesClient CreateLdapConnectionAsync failed to retrieve group managed service account password. [DomainControllerDnsName=unix.local Domain=forest2chld.local UserName=gMSAxxxx$ ] 2022-05-18 10:30:02.5503 Info RemoteImpersonationManager CreateImpersonatorInternalAsync started [UserName=gMSAxxxx$ Domain=forest2.root IsGroupManagedServiceAccount=True] 2022-05-18 10:30:03.3316 Info RemoteImpersonationManager GetGroupManagedServiceAccountTokenAsync finished [UserName=gMSAxxxx$ Domain=forest2.root IsSuccess=False] 2022-05-18 10:30:03.3316 Info RemoteImpersonationManager CreateImpersonatorInternalAsync finished [UserName=gMSAxxxx$ Domain=forest2.root] 2022-05-18 10:30:03.3316 Warn DirectoryServicesClient CreateLdapConnectionAsync failed to retrieve group managed service account password. [DomainControllerDnsName=unix.local Domain=forest2.root UserName=gMSAxxxx$ ] 2022-05-18 10:30:03.3316 Info DirectoryServicesClient TryCreateLdapConnectionAsync failed [exception=Microsoft.Tri.Infrastructure.ExtendedException: CreateLdapConnectionAsync failed [DomainControllerDnsName=unix.local]
This is on a DC in a forest forest3.local (not present in the log above). It seems that it tries to find an account for the unix.local 'domain' (it is a Unix based LDAP, there is a trust between forest2chld.local and unix.local as wel as a two-way trust between forest2.root and forest3.local). It will never succeed.
IMHO it may try this one time, log a message and give up. But is it very agressive and floods the log...
Please Microsoft - there is more in the world than Windows/Active Directory.