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NETGEAR Wireless Cable Modem Gateway Auth Bypass and CSRF

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Sense of Security - Security Advisory - SOS-11-011

Release Date. 20-Sep-2011

Last Update. -

Vendor Notification Date. 22-Mar-2011

Product. NETGEAR Wireless Cable Modem Gateway

CG814WG

Affected versions. Hardware 1.03,

Software V3.9.26 R14 verified,

possibly others

Severity Rating. High

Impact. Authentication bypass,

Cross Site Request Forgery

Attack Vector. Remote without authentication

Solution Status. Upgrade to R15 (by contacting NETGEAR)

CVE reference. Not yet assigned

Details.

The NETGEAR Wireless Cable Modem Gateway CG814WG is supplied by ISP's

as customer premises equipment within Australia and abroad. It is a

centrally managed ISP solution whereby each ISP's devices run a

customised firmware and configuration changes and updates can be pushed

out as required.

Basic authentication is used as the primary and only authentication

mechanism for the administrator interface on the device. The basic

authentication can be bypassed by sending a valid POST request to the

device without sending any authentication header. The response from the

device sends the user to another page that requests basic

authentication, however at this point the request has already been

processed.

An example of attacks using the basic authentication bypass may include

changing the admin password or enabling the remote admin interface

(Internet facing).

Additionally, due to the lack of CSRF protection in the web application,

the bypass attack can be coupled with CSRF to have a victim enable the

remote admin interface to the Internet, where an attacker can then use

the bypass attack again across the remote admin interface to reset the

admin password and access the device. This attack is possible when

targeting a victim that is behind the NETGEAR device on the same segment

as the web administrator interface whom has browsed to a malicious site

containing the CSRF attack.

NETGEAR was notified of this vulnerability on 22 March 2011, but we

never received a response or acknowledgement of the issue or fix. Sense

of Security notified local ISP's and it was escalated by a local ISP

who worked with NETGEAR to develop and test an update. Sense of Security

was never provided an opportunity to validate the fixes in the latest

firmware version. Given the severity of the issue it would be prudent

for NETGEAR to notify and supply an update to all of its customers.

Proof of Concept.

By embedding the below HTML in a website and having a

victim browse to the website the remote management interface to the

Internet would be enabled. An attacker could then use one of the

hardcoded passwords for the device to access it, or use a basic

authentication bypass to change the admin password. Alternatively, the

attacker could conduct a CSRF attack that implements two POST requests

to have the remote admin interface enabled, and the admin password

changed.

The example here is a basic proof of concept, more complex examples

which include JavaScript redirects to mask the basic authentication

pop-up would be more stealthy.


<html>
<head></head>
<body onLoad=javascript:document.form.submit()>
<form action="http://192.168.0.1/goform/RgRemoteManagement"
method="POST" name="form">
<input type="hidden" name="NetgearRmEnable" value="0x01">
<input type="hidden" name="NetgearRmPortNumber" value="1337">
<input type="hidden" name="NetgearUserLevel" value="1">
</form>
</body>
</html>

Solution

Ask your ISP to obtain the latest firmware from NETGEAR and deploy it

to your device.

Discovered by

Sense of Security Labs.

sursa:

 http://www.bugsearch.net/en/12338/netgear-wireless-cable-modem-gateway-auth-bypass-and-csrf.html?ref=2

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