To clearly distinguish between a legitimate security warning and a fake one, consider the following steps and points:

1. Be aware of scams that involve any requests for confidential information, such as passwords, credit card numbers, etc.
   
2. Research the exact details of the warning (apply critical thinking) and compare it to official security alerts.
   
3. Scan your system with a reliable anti-virus/anti-malware software and look up websites for further information.
   
4. Always back up your system regularly to protect yourself from ransomware threats.
   
5. Regularly update your security software and verify emails and links from supposed security professionals.
   
6. Be aware of potential phishing attempts on social media.