Dell TrueMobile 2300 Wireless Broadband Router Authentication Bypass 
Vulnerability

iDefense Security Advisory 12.07.05
www.idefense.com/application/poi/display?id=348&type=vulnerabilities
December 7, 2005

I. BACKGROUND

The Dell TrueMobile 2300 Wireless Broadband Router is an 802.11b/g
wireless access point, wired ethernet switch and internet router. More
information can be found at the following URL:

http://support.dell.com/support/edocs/network/p57205/en/intro/index.htm

II. DESCRIPTION

Remote exploitation of a design error in Dell Inc.'s TrueMobile 2300
Wireless Router may allow an attacker to reset the authentication
credentials.

The Dell TrueMobile 2300 is a wireless router and access point. By
requesting the following url from the router, it is possible to obtain
a page containing a form which allows you to reset the authentication
credentials. (The IP is typically 192.168.2.1, and [ROUTER IP] should
be replace by the router's actual address.)

http://[ROUTER IP]/apply.cgi?Page=adv_password.asp&action=ClearLog

Although dialog boxes for entering the username and password appear,
pressing cancel will not prevent this exploit from working.

III. ANALYSIS

Exploitation could allow remote attackers to associate with the
internal side of the router to change any configuration settings,
including uploading of new firmware.

The precise cause of the error is unknown. Although there is GPL
source code available for this product, the firmware's source code
version has not been kept up to date with the binary version. As a
result, it does not directly allow the cause of the vulnerability to
be determined.

Based on analysis of the affected binary, /usr/sbin/httpd, and the
previous version of the source code it appears the cause is a logic
error involving the 'ClearLog' string being checked without first
ascertaining that the page was one where that made sense. Although
the binary appears to be largely the same code as the available source
code, there are many differences. In the binary version, the
authentication is not performed in the same order as in the source
version. It is likely that the determination of which pages to check
is now done on the basis of the 'action' variable, rather than the
previous method of using the page name.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in the
following Dell TrueMobile 2300 firmware versions:

• 3.0.0.8, dated 07/24/2003
• 5.1.1.6, dated 1/31/2004

Previous versions of this may also be affected, however it is not
clear in which version the vulnerability was introduced.

V. WORKAROUND

In order to mitigate exposure to this vulnerability from remote
attackers, employ encryption on your wireless interface, or disable it
if it is not required. The exact settings to use are dependant on your
wireless security policy. This workaround does not prevent exploitation
from the local network via wired interfaces.

VI. VENDOR RESPONSE

"The vendor is no longer selling this product and has replaced it with
newer models that do not exhibit the defect. Therefore, a patch will not
be released to address this issue."

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2005-3661 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

11/17/2005 Initial vendor notification
11/18/2005 Initial vendor response
12/07/2005 Public disclosure

IX. CREDIT

TNull is credited with the discovery of this vulnerability.

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X. LEGAL NOTICES

Copyright © 2005 iDefense, Inc.

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.