fix: use target FQDN directly for Kerberos SPN when host contains a dot

Reconstructing the remote name as {netbios_hostname}.{targetDomain} produces
the wrong SPN when a host's DNS suffix differs from the AD domain name
(e.g. host.aepsc.com registered in AD vs the constructed host.corp.aepsc.com),
resulting in KDC_ERR_S_PRINCIPAL_UNKNOWN. Use self.host directly when it is
already an FQDN, matching Impacket's smbclient behaviour.

Author: aconite33

nxc/protocols/smb.py

@@ -282,7 +282,8 @@ def enum_host_info(self):
             self.logger.debug(f"Error adding host {self.host} into db: {e!s}")
 
         # DCOM connection with kerberos needed
-        self.remoteName = self.host if not self.kerberos else f"{self.hostname}.{self.targetDomain}"
+        # When the target is already an FQDN, use it directly so the SPN matches the host's AD registration (e.g. host.aepsc.com, not host.corp.aepsc.com).
+        self.remoteName = self.host if (not self.kerberos or "." in self.host) else f"{self.hostname}.{self.targetDomain}"
 
         # using kdcHost is buggy on impacket when using trust relation between ad so we kdcHost must stay to none if targetdomain is not equal to domain
         if not self.kdcHost and self.domain and self.domain == self.targetDomain: