Loki RAT (Relapse) / Directory Traversal - Arbitrary File Delete

[malvuln <malvuln13 () gmail com>]

Discovery / credits: Malvuln - malvuln.com (c) 2022
Original source:
https://malvuln.com/advisory/aabb54951546132e70a8e9f02bf8b5ba.txt
Contact: malvuln13 () gmail com
Media: twitter.com/malvuln

Threat: Loki RAT (Relapse)
Vulnerability: Directory Traversal - Arbitrary File Delete
Description:  The LokiRAT WebUI panel for "LokiRAT_Relapse.exe" runs on PHP
and MySQL and is used control infected hosts through a central server.
The admin webpage "admin.php" takes four parameters pass, command, id and
type. Theres a single check to authenticate $_GET['pass'] against a
hardcoded clear-text password in settings.php.

The backend "admin.php" code has an upload feature, it uses PHP "unlink"
function to delete a file before moving the new one. However, the code does
not
use any secure coding practices, sanitize or filter user input for
directory traversal characters "/../".  This can allow authenticated users,
compromised bots or third-party attackers
who can guess the password check, ability to delete any file E.g. ".php",
".htaccess" etc in the root panel outside the "uploads/" dir, causing Loki
web panel to become inoperative.

admin.php snippet:

  case "upload":
$fullfilename = "uploads/" . $_GET['filename'];
if (file_exists($fullfilename)) unlink ($fullfilename);
move_uploaded_file($_FILES['file']['tmp_name'], $fullfilename);

Family: Loki
Type: WebUI
MD5: aabb54951546132e70a8e9f02bf8b5ba
MD5: 16c33e28c8c9b3ea71249ad94be4bf94 (admin.php)
Vuln ID: MVID-2022-0509
Disclosure: 03/05/2022

Exploit/PoC:
delete "settings.php" file which holds database connection, rendering the
backend inoperative.

http://LOKI-RAT-IP/PHP%20Files/admin.php?pass=test&command=webcam&id=1&type=upload&filename=/../settings.php

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