Password Guessing with THC-Hydra

Hydra is available for Windows and Linux. I've used both, however if you have the need for speed, Linux is the way to go. I'm sure you're itching to get started so I'll stop yapping.

Hydra in its most basic form requires 4 items;

1. target IP address
2. user name (to be used during login process)
3. password (to be used with above username)
4. service (to be brute forced)

hydra -l administrator -p password 192.168.0.1 ftp

However this isn't much fun, not to mention time consuming. Who wants to re-issue the following command over and over again manually.

Instead you can utilize a text file and store passwords you want to try. Hydra can pump through a large text file in minutes.

The easiest switches to remember are -l / -L and -p / -P

Small case switches 'l/p' specify a single set of login credentials at the command line and upper case switches 'L/P' inform Hydra to look in a text file for both the user name and password. Let's say we had a text file with 100,000 words, and we wanted to brute force the Administrator account. We would issue the following command.

hydra -l administrator -P /path/to/file/passwords.txt 192.168.0.1 ftp

What if you want to try different user names, how would that look like?

hydra -L /path/to/file/usernames.txt -P /path/to/file/passwords.txt 192.168.0.1 ftp

If you're brute forcing a remote host on the Internet you could specify a wait period with '-w' switch. On the flip side if you want to see each try on screen, ask Hydra to be verbose with '-v'.

Above example is brute forcing an FTP server. How about a Windows target? Windows authentication is handled by the SMB service. Our new command line would look like this;

hydra -l administrator -P /path/to/file/passwords.txt 192.168.0.1 smb

Before you go crazy, a word of warning and some items to remember:1. Accounts other than Administrator can be locked out. However Administrator can be locked out in special circumstances. Be careful!2. If you don't specify a domain you're brute forcing the local administrator account. 3. Hydra by default attempts 16 parallel connections. This may be too much for some hosts. Adjust this setting with '-t'. For example limiting Hydra to a single connection like this;.

hydra -l administrator -P /path/to/file/passwords.txt -t 1 192.168.0.1 smb

Hydra is easy to use. Above examples should get you started. Next week I'll show you Medusa. Cheers

~Tom

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