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Sunday, January 13, 2019

Chatterbox


CHATTERBOX

- Layout for this exercise:






1 - INTRODUCTION

- The goal for this exercise is to develop a hacking process for the vulnerable machine Chatterbox, what is a retired machine from the Hack The Box pentesting platform:

https://www.hackthebox.eu/


2 - ENUMERATION

- Chatterbox's IP is 10.10.10.74:




- Scanning with Nmap:




- So threre are just two open ports, both of them running the Achat program.



3 - EXPLOITATION

- Searching for exploits related with Achat there are some of them available, for instance the 36025.py what exploits a Remore Buffer Overflow:












- Copying 36025.py to the local working directory:




- Reading 36025.py we learn s that is designed to execute calc.exe at a Windows machine:



etc ....


- Also, by default it uses this server address IP:




- So what we will do is to replace the shellcode provided at 36025.py by using Msfvenom changing the payload, local host and local port:

  • payload -> windows/shell/reverse_tcp
  • LHOST = 10.10.14.8 (my machine)
  • LPORT = 1234 






- Editing 36025.py, copying and pasting here the shellcode originated at previous step with Msfvenom:







- Also, changing the default IP to Chatterbox's IP (10.10.10.74):






- Now, setting a listener session with Metasploit:




- Running 36025.py:






- As a consequence a remote shell is succesfully achieved:





4 - CAPTURING 1st FLAG

- Reading the first flag user.txt is easy:





5 - PRIVILEGE ESCALATION

- However access to the second flag root.txt is denied, so we need Privilege Escalation:





- Remembering that we are running the system as user Alfred:



- There is something weird because user Alfred is the owner of root.txt:






- ICACLS stands for Integrity Control Access Control List, and it displays or modifies discretionary access control lists (DACLs) on specified files, and applies stored DACLs to files in specified directories:

https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/icacls


icacls.exe grants full access to user Alfred over root.txt:





6 - CAPTURING THE 2nd FLAG

- Now it is possible for user Alfred to read root.txt: