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Re: Linksys WRT54 GL - Session riding (CSRF)



Hi Tomaz,
this is not correct, you will be warned that "There is a problem with this website's security certificate." IE7, you will receive a similar warning with Mozilla 2.0.0.11. The Router/ Firewall remains running and stable until you don't accept the certificate.

If the administrator of Linksys WRT54GL is logged into the device and opens a 
malicious website or email with the same browser, he is subject to attacks.

He should be fired...
Imagine the worst case, where the administrator is constantly logged into his 
firewall appliance because he needs to configure changes throughout

He should be fired too...

Regards,
Jan

tomaz.bratusa@xxxxxxxxxxxxxx wrote:
====================================================================================

Team Intell Security Advisory TISA2008-01

------------------------------------------------------------------------------------

Linksys WRT54 GL - Session riding (CSRF)

====================================================================================





Release date:    07.01.2008

Severity:        High

Remote-Exploit:  yes

Impact:          Session riding

Status:          Official patch not available

Software: Linksys WRT54 GL
Tested on:       firmware version 4.30.9

Vendor:          http://www.linksys.com/

Vendor-Status:   informed on 14.08.2007

Disclosed by: Tomaz Bratusa (Team Intell)[TISA-2008-01]




Introduction

============



The Linksys Wireless-G Broadband Router is really three devices in one box. 
First, there's the Wireless Access Point, which lets you connect both screaming 
fast Wireless-G (802.11g at 54Mbps) and Wireless-B (802.11b at 11Mbps) devices 
to the network. There's also a built-in 4-port full-duplex 10/100 Switch to 
connect your wired-Ethernet devices together. Connect four PCs directly, or 
attach more hubs and switches to create as big a network as you need. Finally, 
the Router function ties it all together and lets your whole network share a 
high-speed cable or DSL Internet connection.





Security Risk

=============

Linksys WRT54GL is prone to an authentication-bypass vulnerability. Reportedly, 
the device permits changes in its configuration settings without requring 
authentication (CSRF).







Technical Description

=====================

Linksys WRT54GL is prone to an authentication-bypass vulnerability. The problem 
presents itself when a victim user visits a specially crafted web page on an 
attacker-controlled site. An attacker can exploit this vulnerability to bypass 
authentication and modify the configuration settings of the device.



If the administrator of Linksys WRT54GL is logged into the device and opens a 
malicious website or email with the same browser, he is subject to attacks.

Imagine the worst case, where the administrator is constantly logged into his 
firewall appliance because he needs to configure changes throughout

the day. A malicious link executing unnoticed by the administrator may open the 
firewall.



This issue is reported to affect firmware version 4.30.9; other firmware 
versions may also be affected.





PoC

===

https://192.168.1.1/apply.cgi?submit_button=Firewall&change_action=&action=Apply&block_wan=1&block_loopback=0&multicast_pass=0&ident_pass=0&block_cookie=0&block_java=0&block_proxy=0&block_activex=0&filter=off&_block_wan=1&_block_multicast=0&_ident_pass=1



Folowing the previous link will disable the firewall on 192.168.1.1 on your LAN.





Workaround:
============

1.No official patch yet.



2.Do not surf the web when you are configuring your router.





References:

-------------------------------------------------

http://en.wikipedia.org/wiki/Cross-site_request_forgery



History/Timeline

================

14.08.2007 discovery of the vulnerability

14.08.2007 contacted the vendor
14.08.2008 Response from Cisco - They are working on it

22.10.2007 Request for status

30.10.2007 Response from Cisco - They will include the patch in the next 
firmware upgrade

07.01.2008 advisory is written

07.01.2008 Vulnerability is made public



---------

Contact:

---------



Maldin d.o.o.

Trzaska cesta 2

1000 Ljubljana - SI



tel: +386 (0)590 70 170

fax: +386 (0)590 70 177

gsm: +386 (0)31 816 400

web: www.teamintell.com

www.varnostne-novice.com

e-mail: info(at)teamintell.com





------------

Disclaimer:

------------



The content of this report is purely informational and meant for educational 
purposes only. Maldin d.o.o. shall in no event be liable for any damage 
whatsoever, direct or implied, arising from use or spread of this information. 
Any use of information in this advisory is entirely at user's own risk.




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