Hydra is a famous computer program. Its main job is to try thousands of passwords in seconds to see which one works. Let us learn how it works, what it looks for, and how to stop it completely.
Imagine a robot standing in front of a locked door. Instead of trying to pick the lock, the robot has a massive bucket filled with millions of keys. It tries every single key, one after the other, very fast.
Hydra is that robot, but for computers. It is a tool that tests passwords on login screens. If a password works, Hydra yells, "I found it!" and lets the user in.
"Brute Force" means using pure power instead of being clever.
When Hydra uses a Brute Force attack, it does not know your password. It simply guesses every possible mix of letters and numbers. It tries "A", then "B", all the way to "ZZZZ9999". It takes a long time, but computers never get tired.
Brute force takes too long. So, instead of guessing random letters, Hydra often uses a "Dictionary". This is a long text file filled with the most common passwords humans use. It tries the most obvious guesses first.
When you buy a new internet router or a security camera, it comes with a password from the
factory. Usually, the username is admin and the password is admin or
password.
Many people never change these! Hydra has a special list of these "factory defaults" and tries them first. It works more often than you think.
Smart computer systems do not save your real password. If your password is "Apple", they put
"Apple" through a math blender. It comes out looking like x9K2pQ8. This is
called a Hash.
When you type "Apple" to log in, the computer blends it again and checks if it matches
x9K2pQ8. If bad guys steal the computer's list, they only get the scrambled
mess, not your real password.
Hydra does something called a Parallel Attack. Imagine you have 10 friends. Instead of you trying 10 keys alone, you give 1 key to each friend. Now, 10 keys are being tested at the exact same time. Hydra can test hundreds of passwords at once.
5 GUESSES HAPPENING AT ONCE
Remember the "blender" we talked about earlier? Sometimes attackers use giant text files called Rainbow Tables. These are massive cheat sheets where someone has already put every word in the dictionary into the blender and written down the results. This makes finding a password incredibly fast, without having to do the math every time.
$ hydra -l admin -P passwords.txt 192.168.1.5 ssh
Hydra v9.x starting...
[ATTEMPT] admin : apple
[ATTEMPT] admin : 123456
[SUCCESS] host: 192.168.1.5 login: admin password: summer2024
It does not look like a movie. It is just boring text running very fast.
In the computer world, there are many different types of "doors" or login screens. Hydra is flexible because it knows how to knock on almost all of them. These doors are called Protocols.
Used to control big server computers from far away.
Used to send, receive, and store files.
Used for regular website login screens.
Computers are excellent note-takers. Every time someone tries to open a door and fails, the computer writes it down in a notebook called a Log File.
If a security worker looks at the notebook and sees 5,000 failed attempts in one minute, they instantly know a tool like Hydra is attacking them. It is very loud and leaves a massive trail of evidence.
Once a tool like Hydra finds a password, the attacker can do bad things. They might read private emails, lock the computer and demand money (Ransomware), or use that computer to send spam messages to thousands of other people.
If this tool breaks into things, why do we like it? Good guys (Security Professionals) use Hydra on their own systems on purpose. They want to see if their workers are using weak passwords. If Hydra can break in easily, the security team knows they need to fix the door before a real bad guy finds it.