--------------------------------------------------------------
openSIS <= 7.4 (Bottom.php) Local File Inclusion Vulnerability
--------------------------------------------------------------


[-] Software Link:

https://opensis.com/


[-] Affected Versions:

Version 7.4 and prior versions.


[-] Vulnerability Description:

The vulnerable code is located in the /Bottom.php script:

36.  if(clean_param($_REQUEST['modfunc'],PARAM_ALPHA)=='print')
37.  {
38.    $_REQUEST = $_SESSION['_REQUEST_vars'];
39.    $_REQUEST['_openSIS_PDF'] = true;
40.    if(strpos($_REQUEST['modname'],'?')!==false)
41.      $modname = 
substr($_REQUEST['modname'],0,strpos($_REQUEST['modname'],'?'));
42.    else
43.      $modname = $_REQUEST['modname'];
44.    ob_start();
45.    include('modules/'.$modname);

User input passed through the "modname" request parameter is not 
properly sanitized before being
used in a call to the "include()" function at line 45. This can be 
exploited to include arbitrary
local files and potentially access otherwise restricted functionalities 
or execute arbitrary PHP
code with the permissions of the webserver.


[-] Solution:

No official solution is currently available.


[-] Disclosure Timeline:

[04/11/2019] - Vendor notified
[04/11/2019] - Vendor acknowledgement
[10/01/2020] - Vendor contacted again asking for updates
[16/01/2020] - Vendor tried to fix the vulnerability by using 
"mysqli_real_escape_string()"
[06/02/2020] - Vendor was informed about the inappropriate fix
[25/04/2020] - Version 7.4 released, vulnerability still incorrectly 
fixed
[22/05/2020] - CVE number assigned
[30/06/2020] - Public disclosure


[-] CVE Reference:

The Common Vulnerabilities and Exposures project (cve.mitre.org)
has assigned the name CVE-2020-13383 to this vulnerability.


[-] Credits:

Vulnerability discovered by Egidio Romano.


[-] Original Advisory:

http://karmainsecurity.com/KIS-2020-07