The first thing to do if you suspect your Facebook account has been compromised is to change your password. If you use Facebook to log in to apps such as Spotify or Instagram, change those logins too. This will stop the hacker from accessing these services via your compromised Facebook account.
Hackers can uncover an abundance of personal information in compromised Facebook accounts. Hackers could utilize this information for fraudulent reasons, like taking credit card numbers and spamming people with fake credit card offers or phishing scams. Hackers can also use compromised accounts to send out spam messages or to post on your timeline (as if it was you who committed the crime).
Hackers are most likely to gain access to accounts through exploiting a flaw in the Facebook app’s code. A flaw in the iOS Facebook app allows hackers to hijack cookies, and steal the “access token” of an iPhone user. These tokens which are digital keys, give them complete control over the user’s Facebook Account, as well as any other websites they access using their Facebook credentials.
Hackers may also gain access to an account by using brute force attacks. This method involves figuring out passwords, mostly the most commonly used ones like 123456789 and 1234567890. Hackers can gain access to accounts by scanning compromised credentials. There are numerous free tools to scan for stolen data, such as the popular website HaveIBeenPwned.
https://www.app-ink.net/avg-ultimate-great-protection-for-the-most-gadgets-in-the-house