Small tool created due to some edge cases when trying to exploit the relay using PetitPotam to AD CS.

When you successfuly retrieve a .pfx certificate if the SAN within the X509 differs from the dnshostname attribute of your target you won't be able to retrieve a TGT and have the following error :

KDC_ERR_CLIENT_NAME_MISMATCH (ERR 75)

Here is an example of this edge case :

• FQDN according to the domain : wks2.test.local
• FQDN which is stored within the dnshostname attribute: wks2.modifyme.test.local

This is NOT related to a child domain but just a custom dnshostname value. It has to be noted that a computer account can modify the dnshostname attribute as long as the modification stick to the following value :

• <computer name>.<domain name>

Once you've modified the dnshostname attribute you'll have to request a new certificate and only then you'll be able to ask for a TGT.

LDAPfx.exe DC1:636 wks2_cert.pfx "CN=WKS2,CN=Computers,DC=test,DC=local" "wks2.test.local"
[*] Adding certificate to the LDAPConnection
[*] Requesting LDAPS using the certificate
[*] Current LDAP user : u:TEST\WKS2$
[*] Default naming context : DC=test,DC=local
[*] Current dnshostname attribute : wks2.modifyme.test.local
[*] Did modifying the attribute succeed ? : Success
[*] Current dnshostname attribute : wks2.test.local

Author : @Ottersec & @dav1dstr33t