Prevention is of course the best policy. However, despite your best efforts, you may fall victim - even sophisticated users do. Your data may also be inadvertently exposed and used for malicious purposes. If you suspect that you have been victimized, do not panic. But take action immediately - change your passwords, run a virus scan, and contact your bank or credit card company to report any unauthorized transactions. You can also report to government resources such as the Federal Trade Commission in the US. You may also want to consider contacting a cybersecurity professional for assistance.
Here are some signs to watch for:
Unauthorized Transactions: Check tour bank and credit card statements online regularly (once a day). If you notice any unusual transactions on your bank or credit card statements, that could be a warning that someone has stolen your account information. Sometimes, cyber criminals may charge small amounts (less than $1.00) hoping that you will not notice. Be on the lookout for such transactions. Usually, you will also receive fraud alerts from your financial institution asking you to verify the charge. If you don't recognize a transaction, report it immediately.
Unusual Account Activity: Check for unusual activity, such as new logins, unauthorized changes to your profile, or messages sent from your account that you didn't send. Some websites will show your last login time and location and warn you if they detect an unusual login. However, bad actors are also trying to lure you with such "warning messages" asking you to click on a link to verify. Do not fall for such traps; instead, login securely to your website (preferably from a different device) and check your account activity.
Unresponsive or slow device: If your phone or computer suddenly becomes slow or unresponsive, that could be an indicator that a bad actor has managed to install malware on your system.
Unknown messages: If you receive texts or emails from people or sources you don't know, that may be a phising attempt. A rise in the number of such messages may be an indication that your personal information (phone number or email address) has been compromised.
Calls from your friends and family: Sometimes your friends and family members may receive messages purporting to be you asking them to send money because you are in trouble. If you are ok, thank them and reassure them - then take steps to make sure that you check for unusual patterns. You can also proactively change passwords, notify your financial institutions, and so on.