I did Helpline the unintended way by gaining my initial shell access as NT AUTHORITY\SYSTEM and then working my way back to the root and user flags. Both flags were encrypted for two different users so even with a SYSTEM shell I couldn’t immediately read the files and had to find the user plaintext credentials first. The credentials for user Tolu were especially hard to find: they were hidden in Windows Event Log files and I had to use a Python module to parse those.
Arkham was a medium difficulty box that shows how Java deserialization can be used by attackers to get remote code execution. After finding the JSF viewstates encryption key in a LUKS encrypted file partition, I created a Java deserialization payload using ysoserial to upload netcat and get a shell. After getting to user Batman with credentials found in a backup file, I was able to get access to the administrator directory by mounting the local c: drive via SMB instead of doing a proper UAC bypass.
In this box, I use a simple command injection on the web fortune application that allows me to find the Intermediate CA certificate and its private key. After importing the certificates in Firefox, I can authenticate to the HTTPS page and access a privileged page that generates an SSH private key. Next is SSH port forwarding to access an NFS share, upload my SSH public key to escalate to another user, then recover a pgadmin database which contains the DBA password which is also the root password. Cool box overall, but it should have been rated Hard instead of Insane.
I had trouble with the OTP token on this box: I never figured out why but whenever I scanned the QR code with my Google Authenticator app it would always generate an invalid token. Using a Firefox add-on I was able to properly generate the token to get access to the page. As a nice twist, the login shell was changed to psysh so I couldn’t use the vsftpd exploit to get a full shell on the box. LaCasaDePapel has some typical HTB elements: scavenger hunt for SSH keys, base64 encoding and a cronjob running as root for final priv esc.
This time it’s a very lean box with no rabbit holes or trolls. The box name does not relate to a Capture the Flag event but rather the Compressed Token Format used by RSA securid tokens. The first part of the box involves some blind LDAP injection used to extract the LDAP schema and obtain the token for one of the user. Then using the token, we are able to generate tokens and issue commands on the box after doing some more LDAP injection. The last part of the token was pretty obscure as it involved abusing the listfile parameter in 7zip to trick it into read the flag from root.txt. I was however not able to get a root shell on this box using this technique.
Friendzone is an easy box with some light enumeration of open SMB shares and sub-domains. I used an LFI vulnerability combined with a writable SMB share to get RCE and a reverse shell. A cron job running as root executes a python script every few minutes and the OS module imported by the script is writable so I can modify it and add code to get a shell as root.
Hackback took me a long time to do. There are so many steps required just to get a shell. For extra difficulty, AppLocker is enabled and an outbound firewall policy is configured to block reverse shells. This box has a bit of everything: fuzzing, php, asp (for pivoting with reGeorg), command injection in a Powershell script, some light reversing. For the privesc, I used the diaghub vulnerability and modified an existing exploit to get a bind shell through netcat.
I think Netmon had the quickest first blood on HTB yet. The user flag could be grabbed by just using anonymous FTP and retrieving it from the user directory. I guessed the PRTG admin password after finding an old backup file and changing the year in the password from 2018 to 2019. Once inside PRTG, I got RCE as SYSTEM by creating a sensor and using Nishang’s reverse shell oneliner.
To solve Querier, we find an Excel spreadsheet that contains a VBA macro then use Responder to capture NTLM hashes from the server by forcing it to connect back to our machine with xp_dirtree. After cracking the hash, we gain RCE on the server by using the standard xp_cmdshell command. The Administator credentials are found in a Group Policy Preference file.
Flujab was without a doubt one of the toughest HTB box. It’s got a ton of vhosts that force you to enumerate a lot of things and make sure you don’t get distracted by the quantity of decoys and trolls left around. The key on this box is to stay ‘in scope’ as the box author hinted at before the box was released, so that means enumerating two specific domains without getting distracted by all the other stuff on the box.