Hack The Box: Granny write-up

Granny is an easy Windows OS box from HackTheBox. Hacking it required knowledge of HTTP headers and Windows kernel vulnerabilities.


The first step was running an nmap scan.

Figure 1 – nmap output

The output showed that only port 80 was open. It also showed the server allowed the PUT header in requests, which I confirmed using davtest.

Figure 2 – davtest


This meant I could potentially upload php, html, cfm, jhtml, pl, jsp and txt files to the server, however I could only execute html and txt files. Given this was a Windows box I wanted an aspx shell. Fortunately, the server also permitted requests with the MOVE header, so I decided to try uploading an aspx shell as a txt file and moving it afterwards.

Figure 3 – Creating the shell with msfvenom
Figure 4 – Using curl to upload shell

After creating the shell and submitting it via curl, I checked to see if it was uploaded correctly.

Figure 5 – Confirming txt shell

The last step was to change it back from a txt file to aspx using the MOVE header.

Figure 6 – Shell converted back to aspx using MOVE header

Now I could set up my listener and run the shell.

Figure 7 – Connecting to shell

Privilege escalation

With my shell connected I ran the systeminfo command to get the data for Windows Exploit Suggester (https://github.com/AonCyberLabs/Windows-Exploit-Suggester) and ran the database update on my Kali machine. Then I ran windows-exploit-suggester.py and received the output below.

Figure 8 – Windows exploit suggester

Filtering the results for only ones with “Elevation” gave the results below.

Figure 9 – Windows exploit suggester filtered

I decided to start at the top and work my way down the list. This turned out to be a mistake, as it was the very last exploit on this list, MS09-020, that was successful. I found a working exploit (https://github.com/SecWiki/windows-kernel-exploits/tree/master/MS09-020) and copied it across to the server using the PUT and MOVE headers as I did before, along with a copy of netcat (nc.exe). I also made another shell and sent it over too as I was having difficulty with my original one.

Figure 10 – Moving all files over for privilege escalation

In my unprivileged shell I could confirm all files had moved successfully.

Figure 11 – Privilege escalation files

The last step was simply to set up another listener and launch the exploit using netcat to spawn a privileged shell back to my attacking machine.

Figure 12 – Privileged shell

It should be noted that this machine is also vulnerable to the Churrasco exploit. For an example of how to use this exploit, see Grandpa.

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