CVE-2022-4967 (published 2024-05-14T11:57Z)

strongSwan versions 5.9.2 through 5.9.5 are affected by authorization bypass through improper validation of certificate with host mismatch (CWE-297). When certificates are used to authenticate clients in TLS-based EAP methods, the IKE or EAP identity supplied by a client is not enforced to be contained in the client's certificate. So clients can authenticate with any trusted certificate and claim an arbitrary IKE/EAP identity as their own. This is problematic if the identity is used to make policy decisions. A fix was released in strongSwan version 5.9.6 in August 2022 (e4b4aabc4996fc61c37deab7858d07bc4d220136).


Weakness information:
cwe_id: NVD-CWE-noinfo
cwe_name: Insufficient Information
description: There is insufficient information about the issue to classify it; details are unkown or unspecified.
extended_description: Insufficient Information

Fix information:
repo_url: https://github.com/strongswan/strongswan
commit_details: repo_url: https://github.com/strongswan/strongswan
author: Tobias Brunner
author_date: 2022-02-02 18:39:20+01:00
msg: libtls: Enforce client/server identity when looking for public key

The client already enforces that the server identity is contained in the
received certificate.  But on the server, the referenced commit changed
the lookup from the configured (or adopted if %any was configured) client
identity to the subject DN of the received client certificate.  So any
client with a trusted certificate was accepted.

Fixes: d2fc9b0961c6 ("tls-server: Mutual authentication support for TLS 1.3")
Closes strongswan/strongswan#873
repository: repo_url: https://github.com/strongswan/strongswan
repo_name: strongswan/strongswan
description: strongSwan - IPsec-based VPN
repo_language: C
owner: strongswan
file_changes: filename: tls_peer.c
change_type: ModificationType.MODIFY
diff: @@ -165,7 +165,7 @@ struct private_tls_peer_t {
 
 /* Implemented in tls_server.c */
 bool tls_write_key_share(bio_writer_t **key_share, diffie_hellman_t *dh);
-public_key_t *tls_find_public_key(auth_cfg_t *peer_auth);
+public_key_t *tls_find_public_key(auth_cfg_t *peer_auth, identification_t *id);
 
 /**
  * Verify the DH group/key type requested by the server is valid.
@@ -641,7 +641,7 @@ static status_t process_cert_verify(private_tls_peer_t *this,
 	public_key_t *public;
 	chunk_t msg;
 
-	public = tls_find_public_key(this->server_auth);
+	public = tls_find_public_key(this->server_auth, this->server);
 	if (!public)
 	{
 		DBG1(DBG_TLS, "no trusted certificate found for '%Y' to verify TLS server",
@@ -690,7 +690,7 @@ static status_t process_modp_key_exchange(private_tls_peer_t *this,
 		this->alert->add(this->alert, TLS_FATAL, TLS_INTERNAL_ERROR);
 		return NEED_MORE;
 	}
-	public = tls_find_public_key(this->server_auth);
+	public = tls_find_public_key(this->server_auth, this->server);
 	if (!public)
 	{
 		DBG1(DBG_TLS, "no TLS public key found for server '%Y'", this->server);
@@ -797,7 +797,7 @@ static status_t process_ec_key_exchange(private_tls_peer_t *this,
 		return NEED_MORE;
 	}
 
-	public = tls_find_public_key(this->server_auth);
+	public = tls_find_public_key(this->server_auth, this->server);
 	if (!public)
 	{
 		DBG1(DBG_TLS, "no TLS public key found for server '%Y'", this->server);
@@ -1621,7 +1621,7 @@ static status_t send_key_exchange_encrypt(private_tls_peer_t *this,
 		return NEED_MORE;
 	}
 
-	public = tls_find_public_key(this->server_auth);
+	public = tls_find_public_key(this->server_auth, this->server);
 	if (!public)
 	{
 		DBG1(DBG_TLS, "no TLS public key found for server '%Y'", this->server);

programming_language: C
filename: tls_server.c
change_type: ModificationType.MODIFY
diff: @@ -173,7 +173,7 @@ struct private_tls_server_t {
 /**
  * Find a trusted public key to encrypt/verify key exchange data
  */
-public_key_t *tls_find_public_key(auth_cfg_t *peer_auth)
+public_key_t *tls_find_public_key(auth_cfg_t *peer_auth, identification_t *id)
 {
 	public_key_t *public = NULL, *current;
 	certificate_t *cert, *found;
@@ -184,8 +184,7 @@ public_key_t *tls_find_public_key(auth_cfg_t *peer_auth)
 	if (cert)
 	{
 		enumerator = lib->credmgr->create_public_enumerator(lib->credmgr,
-											KEY_ANY, cert->get_subject(cert),
-											peer_auth, TRUE);
+												KEY_ANY, id, peer_auth, TRUE);
 		while (enumerator->enumerate(enumerator, &current, &auth))
 		{
 			found = auth->get(auth, AUTH_RULE_SUBJECT_CERT);
@@ -923,7 +922,7 @@ static status_t process_cert_verify(private_tls_server_t *this,
 	public_key_t *public;
 	chunk_t msg;
 
-	public = tls_find_public_key(this->peer_auth);
+	public = tls_find_public_key(this->peer_auth, this->peer);
 	if (!public)
 	{
 		DBG1(DBG_TLS, "no trusted certificate found for '%Y' to verify TLS peer",

programming_language: C