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From: Mathy Vanhoef <vanhoefm@gmail.com>
Date: Mon, 29 Jan 2024 17:11:49 +0100
Subject: ap: only accept ptk 4/4 after receiving ptk 2/4
Origin: https://git.kernel.org/pub/scm/network/wireless/iwd.git/commit?id=6415420f1c92012f64063c131480ffcef58e60ca
Bug-Debian: https://bugs.debian.org/1064062
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2023-52161
When operating as an AP, drop message 4 of the 4-way handshake if the AP
has not yet received message 2. Otherwise an attacker can skip message 2
and immediately send message 4 to bypass authentication (the AP would be
using an all-zero ptk to verify the authenticity of message 4).
---
src/eapol.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/src/eapol.c b/src/eapol.c
index bad4bbb7ed37..3ce14d5c07a3 100644
--- a/src/eapol.c
+++ b/src/eapol.c
@@ -2092,6 +2092,10 @@ static void eapol_handle_ptk_4_of_4(struct eapol_sm *sm,
if (L_BE64_TO_CPU(ek->key_replay_counter) != sm->replay_counter)
return;
+ /* Ensure we received Message 2 and thus have a PTK to verify MIC */
+ if (!sm->handshake->have_snonce)
+ return;
+
kck = handshake_state_get_kck(sm->handshake);
if (!eapol_verify_mic(sm->handshake->akm_suite, kck, ek,
--
2.43.0
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