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45 lines
2.0 KiB
45 lines
2.0 KiB
6 years ago
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From 3e34cfdff6b192fe337c6fb3f487f73e96582961 Mon Sep 17 00:00:00 2001
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From: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>
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Date: Sun, 15 Jul 2018 01:25:53 +0200
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Subject: [PATCH] WPA: Ignore unauthenticated encrypted EAPOL-Key data
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Ignore unauthenticated encrypted EAPOL-Key data in supplicant
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processing. When using WPA2, these are frames that have the Encrypted
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flag set, but not the MIC flag.
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When using WPA2, EAPOL-Key frames that had the Encrypted flag set but
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not the MIC flag, had their data field decrypted without first verifying
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the MIC. In case the data field was encrypted using RC4 (i.e., when
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negotiating TKIP as the pairwise cipher), this meant that
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unauthenticated but decrypted data would then be processed. An adversary
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could abuse this as a decryption oracle to recover sensitive information
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in the data field of EAPOL-Key messages (e.g., the group key).
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(CVE-2018-14526)
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Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>
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---
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src/rsn_supp/wpa.c | 11 +++++++++++
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1 file changed, 11 insertions(+)
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diff -upr wpa_supplicant-2.6.orig/src/rsn_supp/wpa.c wpa_supplicant-2.6/src/rsn_supp/wpa.c
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--- wpa_supplicant-2.6.orig/src/rsn_supp/wpa.c 2016-10-02 21:51:11.000000000 +0300
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+++ wpa_supplicant-2.6/src/rsn_supp/wpa.c 2018-08-08 16:55:11.506831029 +0300
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@@ -2016,6 +2016,17 @@ int wpa_sm_rx_eapol(struct wpa_sm *sm, c
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if ((sm->proto == WPA_PROTO_RSN || sm->proto == WPA_PROTO_OSEN) &&
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(key_info & WPA_KEY_INFO_ENCR_KEY_DATA)) {
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+ /*
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+ * Only decrypt the Key Data field if the frame's authenticity
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+ * was verified. When using AES-SIV (FILS), the MIC flag is not
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+ * set, so this check should only be performed if mic_len != 0
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+ * which is the case in this code branch.
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+ */
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+ if (!(key_info & WPA_KEY_INFO_MIC)) {
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+ wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
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+ "WPA: Ignore EAPOL-Key with encrypted but unauthenticated data");
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+ goto out;
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+ }
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if (wpa_supplicant_decrypt_key_data(sm, key, ver, key_data,
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&key_data_len))
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goto out;
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