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If you suspect that your Facebook account has been compromised, you need to change your password immediately. Then, if you are using Facebook for logging into apps like Spotify or Instagram change your logins too. This will stop the hacker from accessing these third-party services via your hacked Facebook account.

A compromised Facebook account can give hackers a treasure trove of personal information. Hackers could make use of this information to carry out malicious motives, such as stealing credit card numbers and sending out fake credit card offers or frauds involving phishing. They can also use the compromised account to send spam messages to friends, or post on your timeline with your name (as in the case that you did it yourself).

Hackers are most likely gain access to an account through exploiting a flaw in the Facebook app code. For instance, a glitch in iOS’s Facebook application allowed hackers to hijack cookies and steal the iPhone user’s “access token.” These tokens are digital keys which grant the user full control over the user’s Facebook account and, thanks to Single Sign-On, other websites that the user uses their Facebook credentials.

A hacker can also gain access to a user’s account through brute force attacks. This technique involves guessing passwords, mostly the most popular ones such as 123456789 and 1234567890. Hackers can gain access to accounts by scanning compromised credentials. There are several tools for free that can be used to scan for stolen information, such as a popular website called HaveIBeenPwned.