Date: Mon, 8 Oct 2012 14:56:47 +0200 From: Timo Warns <Warns@...-Sense.DE> To: oss-security@...ts.openwall.com Subject: [PRE-SA-2012-07] hostapd: Missing EAP-TLS message length validation The issue described below has been reported to the distros list with a timeline as follows: 2012-09-20: - notification of Jouni Malinen of the hostapd project 2012-09-21: - verification of the vulnerability and provision of patch by Jouni Malinen - agreement on an advisory release date of 2012-10-08 2012-09-24: - notification of distros@...openwall.org 2012-10-07: - patch becomes available in hostapd's public git repository 2012-10-08: - release of advisory PRE-CERT Security Advisory ========================== * Advisory: PRE-SA-2012-07 * Released on: 8 October 2012 * Affected product: Hostapd 0.6 - 1.0 * Impact: denial of service * Origin: specially crafted EAP-TLS messages * CVSS Base Score: 7.8 Impact Subscore: 6.9 Exploitability Subscore: 10 CVSS Vector: (AV:N/AC:L/Au:N/C:N/I:N/A:C) * Credit: Timo Warns (PRESENSE Technologies GmbH) * CVE Identifier: CVE-2012-4445 Summary ------- The internal EAP authentication server of hostapd does not sufficiently validate the message length field of EAP-TLS messages, which can be exploited for a denial-of-service via specially crafted EAP-TLS messages (before authentication). Hostapd has a function eap_server_tls_process_fragment() used by its internal EAP authentication server for handling fragmented EAP-TLS messages. The function (indirectly) calls wpabuf_overflow() aborting the application in case of potential buffer overflows. Such a situation can be triggered by an attacker sending an EAP-TLS message with a) the "More Fragments" flag set and b) an "TLS Message Length" value that is smaller than the size of the "TLS Data" field. The vulnerability can be exploited only if hostapd is configured to use its internal EAP authentication server, either directly for IEEE 802.11x or when using hostapd as a RADIUS authentication server. Affected is hostapd in versions 0.6 - 1.0. The issue was introduced with commit http://hostap.epitest.fi/gitweb/gitweb.cgi?p=hostap.git;a=commitdiff;h=34f564dbd5168626da55a7119b04832e98793160 Solution -------- A patch is available at http://w1.fi/gitweb/gitweb.cgi?p=hostap.git;a=commitdiff;h=586c446e0ff42ae00315b014924ec669023bd8de References ---------- When further information becomes available, this advisory will be updated. The most recent version of this advisory is available at: http://www.pre-cert.de/advisories/PRE-SA-2012-07.txt Contact -------- PRE-CERT can be reached under precert@...-secure.de. For PGP key information, refer to http://www.pre-cert.de/.
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