What is a Reverse Brute Force Attack?

Cybersecurity is all about understanding the techniques cybercriminals use to gain access to accounts. One method that is often forgotten is the Reverse Brute Force Attack. In this blog we explain exactly what this attack involves and give advice on how companies and users can protect themselves against it.

The difference between a Brute Force Attack and a Reverse Brute Force Attack

A brute force attack is a widely used technique in which a hacker tries to guess the password of one specific account by testing all kinds of combinations. This often involves software that can try thousands of passwords within a short period of time.

In a Reverse Brute Force Attack, the attacker starts with a known password and tests it against multiple accounts. The goal is to find at least one account that uses this password, especially since people often choose simple passwords, such as "123456" or "welcome." Read more here about a Brute Force Attack.

How do attackers use Reverse Brute Force Attacks?

Cybercriminals often use passwords that have already been leaked. There are online databases available with millions of passwords from previous data breaches. Hackers combine these passwords with data such as email addresses and usernames, which are often publicly accessible. By testing a commonly used password on many different accounts, they increase their chances of gaining access.

This approach works as follows: the hacker chooses a common password, such as "password123," and tries it on thousands of accounts. With a bit of luck, one of the accounts uses this password, giving the attacker immediate access.

The Risks of Reverse Brute Force Attacks

Reverse Brute Force Attacks are dangerous because they are harder to detect. Because hackers don't repeatedly try to log in to one account, but instead test many accounts with the same password, this method is less likely to be noticed quickly by security systems. This type of attack often uses common passwords, which is extra dangerous if users reuse these passwords across multiple accounts.

How do I protect myself against this attack?

Good protection against reverse brute force attacks requires strong, unique passwords and two-factor authentication (2FA). With 2FA, a user must enter an extra code in addition to a password, which makes logging in more difficult for hackers, even if they have the password.

A password manager can create and securely store unique passwords, so users don't have to remember them. It's also important to make employees aware of the risk of weak or reused passwords and to monitor suspicious login attempts. Through early detection, companies can respond faster and prevent attacks.

Read more here about Brute Force Attacks and Dictionary Attacks!