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If you suspect that your Facebook account has been compromised, you must change your password immediately. If you use Facebook as a login for applications such as Spotify or Instagram make sure you change the logins. This will stop hackers from gaining access to these third-party services through your hacked Facebook account.
A compromised Facebook account could provide hackers an unending supply of personal information. Hackers can utilize this information for fraudulent purposes, such as taking credit card numbers and bombarding people with fake credit card offers or frauds involving phishing. They may also use the compromised account to send threatening messages to friends, or even publish on your timeline using your name (as if you did it yourself).
Hackers are likely to gain access to an account through exploiting a weakness in the Facebook app’s code. A flaw in the iOS Facebook application allows hackers to hijack cookies and steal the “access token” of an iPhone user. These tokens, which are digital keys, give the hackers full control over the user’s Facebook Account, as well as any other websites they log into with their Facebook credentials.
Hackers can also gain account access by using brute-force attacks. This method involves figuring out passwords, usually the most commonly used ones like 123456789 and 1234567890. Lastly, hackers can also gain access to an account by scanning for compromised credentials. There are several free tools that can be used to check for stolen information, such as the popular website called HaveIBeenPwned.