KoTH-Hackers TryHackMe Writeup

Scanning

We scanned with the nmap tool all ports with scripts and software versions.

Enumeration

We access web services and we enumerate the corporate website.

We also list several corporate users.

We access the FTP service with the default credentials and download a file called “notes”, where a list of passwords and user names are filtered.

We create a file with listed users and another one with the mentioned passwords.

We tried to brute force the SSH service without success, so we used the dirsearch tool with a medium directory dictionary and listed the “/backdoor/” directory.

We access and find an authentication system, we will probably have to brute force.

After much testing, there was no way and I had to start again from scratch… This time, I reused the listed users and the rockyou dictionary on the FTP service.

Recall that we found a note stating that the user “gcrawford” exposed his cryptographic keys.

Exploitation

Access the FTP service with the new credentials, check hidden files and find the “.ssh” directory with the user’s ssh keys (private included).

We see that the private key is encrypted and we need the key to be able to use it.

We use the “ssh2john” tool to obtain the hash of the “id_rsa” file, crack it with the rockyou dictionary and in a few seconds we obtain the plain password.

We use the password, access by SSH and see that we can run nano on a text file and as the root user.

Privilege Escalation

We run nano with sudo calling the text file, there we will execute commands to obtain a shell as root.

Root prompt

Some of the flags found (the idea was just to root the machine)

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