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HackTheBox/Knife.md

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+# HackTheBox-Knife
+
+## NMAP
+
+```bash
+PORT   STATE SERVICE VERSION
+22/tcp open  ssh     OpenSSH 8.2p1 Ubuntu 4ubuntu0.2 (Ubuntu Linux; protocol 2.0)
+80/tcp open  http    Apache httpd 2.4.41 ((Ubuntu))
+|_http-server-header: Apache/2.4.41 (Ubuntu)
+|_http-title:  Emergent Medical Idea
+Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel
+
+```
+
+## PORT 80 (HTTP)
+
+On the webserver we only get a static web page
+
+<img src="https://imgur.com/DS0Wpof.png"/>
+
+I didn't find anything on the site, it's a php page so I tried default parameters but it didn't work too so I ran a nikto scan which is useful for identifying vulnerabilites on web server
+
+## Nikto
+
+On running `nikto` , I came to know the version of php it's using which is `PHP/8.1.0-dev` 
+
+<img src="https://i.imgur.com/XM762dS.png"/>
+
+On march 2021 this version was implanted with a backdoor which is discovered and removed the github repo,attacker can execute arbitrary code by sending the `User-Agentt` header
+
+https://github.com/vulhub/vulhub/blob/master/php/8.1-backdoor/README.zh-cn.md
+
+So let's test this by following what's in the github repo
+
+<img src="https://i.imgur.com/uQFMweM.png"/>
+
+<img src="https://i.imgur.com/hUjMgJE.png"/>
+
+https://www.zdnet.com/article/official-php-git-server-targeted-in-attempt-to-bury-malware-in-code-base/
+
+This works, according to the finidngs ,the `User-Agnett` header needs `zerodium` and after that we can supply php commands so we could execute commands and get RCE
+
+<img src="https://i.imgur.com/PCHs9oJ.png"/>
+
+We can grab the id_rsa from `james`'s  home folder
+
+<img src="https://i.imgur.com/uW1ZrVu.png"/>
+
+<img src="https://imgur.com/GkGgSxd.png"/>
+
+<img src="https://imgur.com/pVk1WyN.png"/>
+
+But the ssh key doesn't work, so replace the public ssh key 
+
+<img src="https://imgur.com/ZaGkWz3.png"/>
+
+Also add that public key to `authorized_keys`
+
+<img src="https://imgur.com/RiIuKHY.png"/>
+
+Doing `sudo -l` we can see what we can run as sudo
+
+<img src="https://i.imgur.com/19IVrRC.png"/>
+
+Let's see the help menu for `knife`
+
+<img src="https://imgur.com/siHnCjm.png"/>
+
+If we scroll down a little we can that we can execute ruby scripts meaning we can run shell commands
+
+<img src="https://i.imgur.com/40qvgXB.png"/>
+
+<img src="https://i.imgur.com/nUrxDs0.png"/>
+
+So I added my public ssh key in `/root/.ssh/authorized_keys/` . we could have gotten a reverse shell or made bash SUID
+
+<img src="https://imgur.com/Pmn5exA.png"/>
+
+Getting a reverse shell
+
+<img src="https://i.imgur.com/dwXMO4J.png"/>