ldapauth: Use specified domain in NTLM auth msg instead of target name

ldapauth/ldap.go

@@ -243,7 +243,9 @@ func bind(
 
 		tlsState, ok := conn.TLSConnectionState()
 		if ok && !opts.DisableChannelBinding {
-			bindRequest.Negotiator = ntlmNegotiatorWithChannelBinding(tlsState.PeerCertificates[0])
+			bindRequest.Negotiator = ntlmNegotiatorWithChannelBinding(tlsState.PeerCertificates[0], creds.Domain)
+		} else {
+			bindRequest.Negotiator = ntlmNegotiatorForDomain(creds.Domain)
 		}
 
 		_, err = conn.NTLMChallengeBind(bindRequest)

ldapauth/ntlm.go

@@ -10,13 +10,18 @@ import (
 )
 
 type ntlmNegotiator struct {
-	cert *x509.Certificate
+	cert               *x509.Certificate
+	overrideTargetName string
 }
 
 var _ ldap.NTLMNegotiator = &ntlmNegotiator{}
 
-func ntlmNegotiatorWithChannelBinding(cert *x509.Certificate) ldap.NTLMNegotiator {
-	return &ntlmNegotiator{cert: cert}
+func ntlmNegotiatorWithChannelBinding(cert *x509.Certificate, domain string) ldap.NTLMNegotiator {
+	return &ntlmNegotiator{cert: cert, overrideTargetName: domain}
+}
+
+func ntlmNegotiatorForDomain(domain string) ldap.NTLMNegotiator {
+	return &ntlmNegotiator{overrideTargetName: domain}
 }
 
 func (n *ntlmNegotiator) Negotiate(domain string, worktation string) ([]byte, error) {
@@ -48,6 +53,17 @@ func (n *ntlmNegotiator) ChallengeResponse(challenge []byte, username string, ha
 		cm.TargetInfo.List = cm.TargetInfo.List[:len(cm.TargetInfo.List)-1]
 	}
 
+	// Authenticate with the domain name that was specified, not the domain that
+	// the server advertises. This grants compatibility with the LDAP SOCKS
+	// feature of ntlmrelayx.py which is sensitive to the exact domain name (DNS
+	// vs NetBIOS name).
+	if n.overrideTargetName != "" && n.overrideTargetName != "." {
+		cm.TargetName, err = ntlm.CreateStringPayload(n.overrideTargetName)
+		if err != nil {
+			return nil, fmt.Errorf("override target name: create string payload: %w", err)
+		}
+	}
+
 	// add channel bindings
 	cm.TargetInfo.AddAvPair(ntlm.MsvChannelBindings, ChannelBindingHash(n.cert))
 	cm.TargetInfo.AddAvPair(ntlm.MsvAvEOL, nil)