Brad Bishop | 1a4b7ee | 2018-12-16 17:11:34 -0800 | [diff] [blame^] | 1 | hostapd-2.6: Fix CVE-2018-14526 |
| 2 | |
| 3 | [No upstream tracking] -- https://w1.fi/security/2018-1/unauthenticated-eapol-key-decryption.txt |
| 4 | |
| 5 | wpa: Ignore unauthenticated encrypted EAPOL-Key data |
| 6 | |
| 7 | Ignore unauthenticated encrypted EAPOL-Key data in supplicant |
| 8 | processing. When using WPA2, these are frames that have the Encrypted |
| 9 | flag set, but not the MIC flag. |
| 10 | |
| 11 | When using WPA2, EAPOL-Key frames that had the Encrypted flag set but |
| 12 | not the MIC flag, had their data field decrypted without first verifying |
| 13 | the MIC. In case the data field was encrypted using RC4 (i.e., when |
| 14 | negotiating TKIP as the pairwise cipher), this meant that |
| 15 | unauthenticated but decrypted data would then be processed. An adversary |
| 16 | could abuse this as a decryption oracle to recover sensitive information |
| 17 | in the data field of EAPOL-Key messages (e.g., the group key). |
| 18 | |
| 19 | Upstream-Status: Backport [https://w1.fi/cgit/hostap/commit/src/rsn_supp/wpa.c?id=3e34cfdff6b192fe337c6fb3f487f73e96582961] |
| 20 | CVE: CVE-2018-14526 |
| 21 | Signed-off-by: Andrej Valek <andrej.valek@siemens.com> |
| 22 | |
| 23 | diff --git a/src/rsn_supp/wpa.c b/src/rsn_supp/wpa.c |
| 24 | index 3c47879..6bdf923 100644 |
| 25 | --- a/src/rsn_supp/wpa.c |
| 26 | +++ b/src/rsn_supp/wpa.c |
| 27 | @@ -2016,6 +2016,17 @@ int wpa_sm_rx_eapol(struct wpa_sm *sm, const u8 *src_addr, |
| 28 | |
| 29 | if ((sm->proto == WPA_PROTO_RSN || sm->proto == WPA_PROTO_OSEN) && |
| 30 | (key_info & WPA_KEY_INFO_ENCR_KEY_DATA)) { |
| 31 | + /* |
| 32 | + * Only decrypt the Key Data field if the frame's authenticity |
| 33 | + * was verified. When using AES-SIV (FILS), the MIC flag is not |
| 34 | + * set, so this check should only be performed if mic_len != 0 |
| 35 | + * which is the case in this code branch. |
| 36 | + */ |
| 37 | + if (!(key_info & WPA_KEY_INFO_MIC)) { |
| 38 | + wpa_msg(sm->ctx->msg_ctx, MSG_WARNING, |
| 39 | + "WPA: Ignore EAPOL-Key with encrypted but unauthenticated data"); |
| 40 | + goto out; |
| 41 | + } |
| 42 | if (wpa_supplicant_decrypt_key_data(sm, key, ver, key_data, |
| 43 | &key_data_len)) |
| 44 | goto out; |