Huawei B153 3G/UMTS router WPS weakness

[ADVISORY INFORMATION]
Title: Huawei B153 3G/UMTS router WPS weakness
Discovery date: 21/05/2013
Release date: 05/08/2013
Advisory URL: http://blog.emaze.net/2013/08/huawei-b153-3gumts-router-wps-weakness.html
Credits: Roberto Paleari ([email protected], @rpaleari)
Alessandro Di Pinto ([email protected], @adipinto)

[VULNERABILITY INFORMATION]
Class: Authentication bypass

[AFFECTED PRODUCTS]
We confirm the presence of the security vulnerability on the following
products/firmware versions:

• Huawei B153 3G/UMTS router, software version 1096.11.405.03.111sp02

Other device models and firmware versions are probably also vulnerable, but
they were not checked.

As required by the ISP that distributes this device to end-users, we do not
disclose the full commercial name of the product, but only the manufacturer
device model (i.e., Huawei B153).

[VULNERABILITY DETAILS]
To allow wireless users to easily authenticate to the WPA2 Wi-Fi network, the
Huawei B153 device supports the WPS procotol [1]. The WPS "External Registrar"
PIN-base method is notoriously insecure, as allows attackers to brute force the
access PIN in few hours [2].

In the default device configuration, the WPS daemon is configured to accept WPS
PIN authentication attempts, but no WPS PIN is configured. Thus, the device is
supposed to reject any possible PIN-based WPS request, allowing only the "push
button" mechanism, that requires physical interaction.

Unfortunately we detected that, despite no WPS PIN is actually configured, a
specially-crafted WPS session can still force the device to complete the
"External Registrar" handshake, returning to the attacker the current WPA2
passphrase. In other terms attackers located within the wireless range of the
device can instantly recover the WPA passphrase. We would also like to stress
out that this vulnerability is present in the default device configuration, and
no user action is required.

This attack cannot be exploited using publicly available tools: no "standard"
WPS cracking tool performs handshakes using the specially-crafted WPS session
required to exploit this security issue. As a consequence, we implemented our
proof-of-concept as a small patch to the reaver WPS cracking tool [3] (the
unmodified version of reaver cannot recover the password for this device).

Footnotes:
[1] http://en.wikipedia.org/wiki/Wi-Fi_Protected_Setup
[2] http://www.kb.cert.org/vuls/id/723755
[3] https://code.google.com/p/reaver-wps/

[REMEDIATION]
Huawei has released an updated firmware version that addresses this issue.

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Copyright(c) Emaze Networks S.p.A 2013, All rights reserved worldwide.
Permission is hereby granted to redistribute this advisory, providing that no
changes are made and that the copyright notices and disclaimers remain intact.

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