Introduction

Hydra is a brute force online password cracking program, a quick system login password “hacking” tool.

Hydra can run through a list and “brute force” some authentication services. Imagine trying to manually guess someone’s password on a particular service (SSH, Web Application Form, FTP or SNMP) - we can use Hydra to run through a password list and speed this process up for us, determining the correct password.

According to its official repository, Hydra supports, i.e., has the ability to brute force the following protocols: “Asterisk, AFP, Cisco AAA, Cisco auth, Cisco enable, CVS, Firebird, FTP, HTTP-FORM-GET, HTTP-FORM-POST, HTTP-GET, HTTP-HEAD, HTTP-POST, HTTP-PROXY, HTTPS-FORM-GET, HTTPS-FORM-POST, HTTPS-GET, HTTPS-HEAD, HTTPS-POST, HTTP-Proxy, ICQ, IMAP, IRC, LDAP, MEMCACHED, MONGODB, MS-SQL, MYSQL, NCP, NNTP, Oracle Listener, Oracle SID, Oracle, PC-Anywhere, PCNFS, POP3, POSTGRES, Radmin, RDP, Rexec, Rlogin, Rsh, RTSP, SAP/R3, SIP, SMB, SMTP, SMTP Enum, SNMP v1+v2+v3, SOCKS5, SSH (v1 and v2), SSHKEY, Subversion, TeamSpeak (TS2), Telnet, VMware-Auth, VNC and XMPP.”

For more information on the options of each protocol in Hydra, you can check the Kali Hydra tool page.

This shows the importance of using a strong password; if your password is common, doesn’t contain special characters and is not above eight characters, it will be prone to be guessed. A one-hundred-million-password list contains common passwords, so when an out-of-the-box application uses an easy password to log in, change it from the default! CCTV cameras and web frameworks often use admin:password as the default login credentials, which is obviously not strong enough.

Hydra Commands

The options we pass into Hydra depend on which service (protocol) we’re attacking. For example, if we wanted to brute force FTP with the username being user and a password list being passlist.txt, we’d use the following command:

hydra -l user -P passlist.txt ftp://MACHINE_IP

For this deployed machine, here are the commands to use Hydra on SSH and a web form (POST method).

SSH

hydra -l <username> -P <full path to pass> MACHINE_IP -t 4 ssh

For example, hydra -l root -P passwords.txt MACHINE_IP -t 4 ssh will run with the following arguments:

• Hydra will use root as the username for ssh
• It will try the passwords in the passwords.txt file
• There will be four threads running in parallel as indicated by t 4

Post Web Form

We can use Hydra to brute force web forms too. You must know which type of request it is making; GET or POST methods are commonly used. You can use your browser’s network tab (in developer tools) to see the request types or view the source code.