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 (roberto@greyhats.it, 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.