Bug 1332422 (CVE-2016-4476)

Summary:	CVE-2016-4476 wpa_supplicant, hostapd: denial of service via crafted WPA/WPA2 passphrase parameter
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	blueowl, carnil, dcbw, linville, lkundrak, negativo17, rkhan, slawomir
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	wpa_supplicant 2.6	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-07-19 02:30:14 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1332425, 1332426, 1332427
Bug Blocks:	1332428

Description Andrej Nemec 2016-05-03 07:34:08 UTC

A vulnerability was found in how hostapd and wpa_supplicant writes the
configuration file update for the WPA/WPA2 passphrase parameter. If this
parameter has been updated to include control characters either through
a WPS operation or through local configuration change over the
wpa_supplicant control interface, the resulting configuration file may
prevent the hostapd and wpa_supplicant from starting when the updated
file is used.

References:

http://seclists.org/oss-sec/2016/q2/187

Comment 1 Andrej Nemec 2016-05-03 07:40:30 UTC

Created hostapd tracking bugs for this issue:

Affects: fedora-all [bug 1332425]
Affects: epel-all [bug 1332427]

Comment 2 Andrej Nemec 2016-05-03 07:40:38 UTC

Created wpa_supplicant tracking bugs for this issue:

Affects: fedora-all [bug 1332426]

Comment 3 Doran Moppert 2016-07-18 07:38:16 UTC

Prerequisites for the flaw to be exploitable are described upstream at 
http://w1.fi/security/2016-1/psk-parameter-config-update.txt

> WPS needs to be enabled in the runtime operation and the WPS operation
> needs to have been authorized by the local user over the control
> interface. For wpa_supplicant, update_config=1 must have been enabled in
> the configuration file.

RHEL-6 and -7 versions have CONFIG_WPS enabled, however default configuration 
does not include the `update_config=1` flag.

Normally, network connections are managed by NetworkManager which gives 
credentials to wpa_supplicant over DBus.  It is possible to send invalid byte 
sequences as part of the key, but this flaw only comes into effect if 
wpa_supplicant itself writes these sequences into its config file and then 
attempts to re-read the file.

Turning `update_config=1` on is not recommended since it allows users who can 
use the control interface to overwrite the entire wpa_supplicant 
configuration.