Netgear DGN1000 / DGN2200 Authentication Bypass / Command Execution

2013-06-05T00:00:00
ID 1337DAY-ID-20847
Type zdt
Reporter Roberto Paleari
Modified 2013-06-05T00:00:00

Description

Netgear DGN1000 with firmware version prior to 1.1.00.48 and Netgear DGN2200 version 1 suffer from authentication bypass and command execution vulnerabilities.

                                        
                                            Unauthenticated command execution on Netgear DGN devices
========================================================

[ADVISORY INFORMATION]
Title:    Unauthenticated command execution on Netgear DGN devices
Discovery date: 01/05/2013
Release date:   31/05/2013
Credits:        Roberto Paleari ([email protected], twitter: @rpaleari)

[VULNERABILITY INFORMATION]
Class:           Authentication bypass, command execution

[AFFECTED PRODUCTS]
This security vulnerability affects the following products and firmware
versions:
   * Netgear DGN1000, firmware version < 1.1.00.48
   * Netgear DGN2200 v1
Other products and firmware versions are probably also vulnerable, but they
were not checked.

[VULNERABILITY DETAILS]
Attackers can leverage this vulnerability to bypass existing authentication
mechanisms and execute arbitrary commands on the affected devices, with root
privileges.

Briefly, the embedded web server skips authentication checks for some URLs
containing the "currentsetting.htm" substring. As an example, the following URL
can be accessed even by unauthenticated attackers:

http://<target-ip-address>/setup.cgi?currentsetting.htm=1

Then, the "setup.cgi" page can be abused to execute arbitrary commands. As an
example, to read the /www/.htpasswd local file (containing the clear-text
password for the "admin" user), an attacker can access the following URL:

http://<target-ip-address>/setup.cgi?next_file=netgear.cfg&todo=syscmd&cmd=cat+/www/.htpasswd&curpath=/&currentsetting.htm=1

Basically this URL leverages the "syscmd" function of the "setup.cgi" script to
execute arbitrary commands. In the example above the command being executed is
"cat /www/.htpasswd", and the output is displayed in the resulting web
page. Slightly variations of this URL can be used to execute arbitrary
commands.

[REMEDIATION]
For DGN1000, Netgear included a fix for this issue inside firmware version
1.1.00.48. According to Netgear, DGN2200 v1 is not supported anymore, while v3
and v4 should not be affected by this issue; these versions were not tested by
the author.

#  0day.today [2018-01-05]  #