Bug 1332423 (CVE-2016-4477)

Summary:	CVE-2016-4477 wpa_supplicant: local configuration update allows privilege escalation
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	blueowl, carnil, dcbw, lkundrak, 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 02:29:28 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:	1332426
Bug Blocks:	1332428

Description Andrej Nemec 2016-05-03 07:38:47 UTC

The local configuration update through the control interface SET_NETWORK
command could allow privilege escalation for the local user to run code
from a locally stored library file under the same privileges as the
wpa_supplicant process has. The assumption here is that a not fully
trusted user/application might have access through a connection manager
to set network profile parameters like psk, but would not have access to
set other configuration file parameters. If the connection manager in
such a case does not filter out control characters from the psk value,
it could have been possible to practically update the global parameters
by embedding a newline character within the psk value. In addition, the
untrusted user/application would need to be able to install a library
file somewhere on the device from where the wpa_supplicant process has
privileges to load the library.

References:

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

Comment 1 Andrej Nemec 2016-05-03 07:40:45 UTC

Created wpa_supplicant tracking bugs for this issue:

Affects: fedora-all [bug 1332426]

Comment 2 Andrej Nemec 2016-05-04 07:08:15 UTC

External references:

http://w1.fi/security/2016-1/

Comment 3 Doran Moppert 2016-07-18 07:32:59 UTC

From the upstream report linked in comment 2:

> For the local control interface attack vector (CVE-2016-4477):
> 
> wpa_supplicant v0.4.0-v2.5 with control interface enabled
> 
> update_config=1 must have been enabled in the configuration file.

wpa_supplicant versions shipped in RHEL 5-7 are within the affected versions;  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.