Allied Telesis AT-RG634A ADSL Broadband Router - Unauthenticated Webshell

                                                *Title:*

Allied Telesis AT-RG634A ADSL Broadband router hidden administrative
unauthenticated webshell.

*Vulnerability Information:*
- CVE: CVE-2014-1982
- Type of Vulnerability:
  - CWE-78  : OS Command Injection
  - CWE-306 : Missing Authentication for Critical Function

*Affected products:*

- Allied Telesis AT-RG634A ADSL Broadband router. (version 3.3+ and
probably others)

Other products like,
   - Allied Telesis iMG624A  (firmware version, 3.5)
   - Allied Telesis iMG616LH (firmware version, +2.4)
   - Allied Telesis iMG646BD (firmware version, 3.5)

*Vendor:*
- Allied Telesis : http://www.alliedtelesis.com//


has the same vulnerbility, but the vendor reports that the version
3.8.05 of the firmware has already addressed this issue, but we where
unable to test nor confirm this information.

*Security Patches / Workaround:*

- Allied Telesis has noted that the AT-RG634A product is no longer
supported, but gives a workaround
to mitigate the issue.

Configure the device so that only trusted devices can
access the target device using the following command,

"WEBSERVER SET MANAGEMENTIP <ip-address>"

*Short Description:*

The Allied Telesis AT-RG634A ADSL Broadband router has a hidden url
page in their admnistrative HTTP interface capable of executing
commands as admin without requiring any kind of authentication.

*Description:*

"The AT-RG634 is a full-featured, broadband media gateway and router
designed for cost-effective delivery of advanced IP Triple Play voice,
video and data services over an ADSL infrastructure. The RG634
supports Layer 3 functions, including NAT, DMZ, and Stateful
inspection firewall for delivery of revenue-generating services such
as home networking and security services." (from
www.alliedtelesis.com/p-2345.html)

The Allied Telesis AT-RG634A ADSL Broadband router has a hidden URL
(/cli.html) page to execute CLI command with admin priviledges,
available by default and without any kind of authentication.

Having as impact a total compromise of the target device.

*Steps to reproduce:*

- Connect via HTTP to the hidden page http://<device IP>/cli.html a
input box is shown, every command typed there will be executed as admin.

Entering the following lines in the hidden page (/cli.html) a new
telnet admin user called "eviluser" is added to the system.

>> system add login eviluser system set user eviluser access
>> superuser.


*Credits:*

This security issue was discovered and researched by Sebastian Muniz
(topo), Security Researcher of Groundworks Technologies
(http://www.groundworkstech.com)


*License:*

The contents of this advisory are copyright (c) 2014 Groundworks
Technologies,and are licensed under a Creative Commons Attribution
Non-Commercial Share-Alike 3.0 (United States) License:
http://creativecommons.org/licenses/by-nc-sa/3.0/us/