3Com OfficeConnect Wireless Cable/DSL Router Authentication Bypass

[luca.caretton@xxxxxxxxxxxx]

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Security Research Advisory

Vulnerability name:
"3Com OfficeConnect Wireless Cable/DSL Router Authentication Bypass"
Advisory number: LC-2008-05
Advisory URL: http://www.ikkisoft.com

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1) Affected Hardware/Software 

* 3CRWE554G72 
  (Hardware version: 3COM_AP51_v01, Software version: 1.2.0 - Nov 14,2006)
  
Product URL: 
http://www.3com.com/products/en_US/detail.jsp?tab=features&sku=3CRWE554G72&pathtype=support

Other recent versions, as well as similar 3Com devices, may be affected 
due to the shared firmware code base.

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2) Severity 

Severity: Medium
Local/Remote: Remote

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3) Summary

"The 3Com OfficeConnect Wireless Cable/DSL Router is a high-speed, affordable, 
and easy-to-use small office solution that lets wireless and wired PCs and 
laptops securely share a single broadband Internet connection." 

This device is very common due to the affordable price and versatility. 
For these reasons it is widely installed by large telecom providers in all 
Europe
(e.g. In Poland, Orange is currently deploying this device for its residential 
DSL). 

This device is prone to an authentication bypass vulnerability which permits 
to retrieve the complete system configuration as well as the services 
credentials (e.g. web console, wifi network).

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4) Vulnerability Details

The 3Com OfficeConnect Wireless Cable/DSL Router suffers an authentication 
bypass vulnerability due to an improper authentication/authorization mechanism.

In order to manage the device, an easy to use web console is enabled by default 
from the internal network and (optionally) from the Internet. 
Even if the http daemon does not permit to access HTML pages and the web 
console 
without authentication, it is still possible to invoke and execute 
existent CGI programs. Unfortunately, the "System 
Tools-->Configuration-->Backup 
Configuration" functionality saves the actual system configuration in a 
persistent plain-text file named "config.bin" using a custom CGI program. 
An unauthenticated user may directly invoke the "SaveCfgFile" CGI program and 
easily download the system configuration containing configuration information, 
users, passwords, wifi keys and other sensitive information.

Note: if the "Remote Administration" option is enabled, this vulnerability may 
be exploited from the Internet as well.

Example of sensitive content within the "config.bin" file:
[...]
pppoe_username=xxxxxxxxxxxxxxx
pppoe_password=xxxxxxxxx
pppoe_service_name=xxxxxxxxx
[...]
mradius_username=xxxxxx
mradius_password=xxxxxx
mradius_secret=xxxxxxx
[...]
http_username=xxxxx
login_password=xxxxx
http_passwd=xxxxx
[...]
AuthName=xxxxxxx
AuthPassword=xxxx
snmpStatus=xxxxxxx
snmpRoCommunity=xxxxxxxx
snmpRwCommunity=xxxxxxxx
[...]
multi_dmz_wan_ip1=xxxxxxxxxx
[...]
lan_macaddr=xxxxxxxxxxxxx
[...]

Later on, looking for similar vulnerabilities in the Bugtraq database, 
I've found a similar finding discovered by Patrik, cqure.net 
(iDEFENSE Security Advisory 01.20.05). As far as I know and I can understand 
from the firmware versions reported, this issue seems to be a further 
authentication bypass technique due to an insufficient patch supplied 
by the vendor.  

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5) Exploit 

Attackers may exploit this flaw through a common web browser.

http://<IP>/SaveCfgFile.cgi

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6) Fix Information 

To reduce the overall exploitability, disable the "Remote Administration" 
option. However, a firmware update is required in order to resolve this issue.

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7) Time Table 

08/12/2008 - Vendor notified via "3Com Vulnerability Disclosure Form"
??/??/???? - Vendor response.
??/??/???? - Vendor patch release.
09/02/2009 - Public disclosure.

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8) Credits 

Discovered by Luca Carettoni - luca.carettoni[at]ikkisoft[dot]com

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9) Legal Notices

The information in the advisory is believed to be accurate at the time of
publishing based on currently available information. 
This information is provided as-is, as a free service to the community. 
There are no warranties with regard to this information.
The author does not accept any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.
Permission is hereby granted for the redistribution of this alert, provided 
that the content is not altered in any way, except reformatting, and that due 
credit is given.

This vulnerability has been disclosed in accordance with the RFP 
Full-Disclosure Policy v2.0, available at:
http://www.wiretrip.net/rfp/policy.html

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