CVE-2015-4171_enforce_remote_auth added, fix potential leak of authentication credential to rogue server when using PSK or EAP. This is CVE-2015-4171.

3 files changed, 105 insertions, 0 deletions

diff --git a/debian/changelog b/debian/changelog
index 38395b62b..a218f1da9 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -5,6 +5,9 @@ strongswan (5.3.1-1) UNRELEASED; urgency=medium
     - strongswan-5.2.2-5.3.0_unknown_payload dropped, included upstream.
     - 05_ivgen-allow-reusing-same-message-id-twice added, allow reusing the
     same message ID twice in sequential IV gen. strongSwan issue #980.
+    - CVE-2015-4171_enforce_remote_auth added, fix potential leak of
+    authentication credential to rogue server when using PSK or EAP. This is
+    CVE-2015-4171.
 
  -- Yves-Alexis Perez <corsac@debian.org>  Mon, 01 Jun 2015 15:00:41 +0200
 
diff --git a/debian/patches/CVE-2015-4171_enforce_remote_auth.patch b/debian/patches/CVE-2015-4171_enforce_remote_auth.patch
new file mode 100644
index 000000000..506a55f6f
--- /dev/null
+++ b/debian/patches/CVE-2015-4171_enforce_remote_auth.patch
@@ -0,0 +1,101 @@
+From ca1a65cc6aef2e037b529574783b7c571d1d82a9 Mon Sep 17 00:00:00 2001
+From: Martin Willi <martin@strongswan.org>
+Date: Wed, 3 Jun 2015 10:52:34 +0200
+Subject: [PATCH] ikev2: Enforce remote authentication config before proceeding
+ with own authentication
+
+Previously the constraints in the authentication configuration of an
+initiator were enforced only after all authentication rounds were
+complete.  This posed a problem if an initiator used EAP or PSK
+authentication while the responder was authenticated with a certificate
+and if a rogue server was able to authenticate itself with a valid
+certificate issued by any CA the initiator trusted.
+
+Because any constraints for the responder's identity (rightid) or other
+aspects of the authentication (e.g. rightca) the initiator had were not
+enforced until the initiator itself finished its authentication such a rogue
+responder was able to acquire usernames and password hashes from the client.
+And if a client supported EAP-GTC it was even possible to trick it into
+sending plaintext passwords.
+
+This patch enforces the configured constraints right after the responder's
+authentication successfully finished for each round and before the initiator
+starts with its own authentication.
+
+Fixes CVE-2015-4171.
+---
+ src/libcharon/sa/ikev2/tasks/ike_auth.c | 44 +++++++++++++++++++++++++++++++++
+ 1 file changed, 44 insertions(+)
+
+diff --git a/src/libcharon/sa/ikev2/tasks/ike_auth.c b/src/libcharon/sa/ikev2/tasks/ike_auth.c
+index bf747a49edde..2554496c1916 100644
+--- a/src/libcharon/sa/ikev2/tasks/ike_auth.c
++++ b/src/libcharon/sa/ikev2/tasks/ike_auth.c
+@@ -112,6 +112,11 @@ struct private_ike_auth_t {
+ 	 * received an INITIAL_CONTACT?
+ 	 */
+ 	bool initial_contact;
++
++	/**
++	 * Is EAP acceptable, did we strictly authenticate peer?
++	 */
++	bool eap_acceptable;
+ };
+ 
+ /**
+@@ -879,6 +884,37 @@ static void send_auth_failed_informational(private_ike_auth_t *this,
+ 	message->destroy(message);
+ }
+ 
++/**
++ * Check if strict constraint fullfillment required to continue current auth
++ */
++static bool require_strict(private_ike_auth_t *this, bool mutual_eap)
++{
++	auth_cfg_t *cfg;
++
++	if (this->eap_acceptable)
++	{
++		return FALSE;
++	}
++
++	cfg = this->ike_sa->get_auth_cfg(this->ike_sa, TRUE);
++	switch ((uintptr_t)cfg->get(cfg, AUTH_RULE_AUTH_CLASS))
++	{
++		case AUTH_CLASS_EAP:
++			if (mutual_eap && this->my_auth)
++			{
++				this->eap_acceptable = TRUE;
++				return !this->my_auth->is_mutual(this->my_auth);
++			}
++			return TRUE;
++		case AUTH_CLASS_PSK:
++			return TRUE;
++		case AUTH_CLASS_PUBKEY:
++		case AUTH_CLASS_ANY:
++		default:
++			return FALSE;
++	}
++}
++
+ METHOD(task_t, process_i, status_t,
+ 	private_ike_auth_t *this, message_t *message)
+ {
+@@ -1014,6 +1050,14 @@ METHOD(task_t, process_i, status_t,
+ 		}
+ 	}
+ 
++	if (require_strict(this, mutual_eap))
++	{
++		if (!update_cfg_candidates(this, TRUE))
++		{
++			goto peer_auth_failed;
++		}
++	}
++
+ 	if (this->my_auth)
+ 	{
+ 		switch (this->my_auth->process(this->my_auth, message))
+-- 
+1.9.1
+
diff --git a/debian/patches/series b/debian/patches/series
index 169e70542..c2bce201f 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -2,3 +2,4 @@
 03_systemd-service.patch
 04_disable-libtls-tests.patch
 05_ivgen-allow-reusing-same-message-id-twice.patch
+CVE-2015-4171_enforce_remote_auth.patch