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False Positives: Why do they happen and how can we evade them?

False Positives: Why do they happen and how can we evade them?
May 02, 2024

Antivirus software plays a crucial role in protecting your computer and phone from malicious programs (malware). But have you ever wondered how it actually identifies these threats? Let us trace the inner workings of antivirus software, exploring how it scans files and flags them as malware. 

There Are Two Main Techniques: Signatures and Heuristics

There are two primary methods antivirus software uses to detect malware:

1. Signature-based Detection:

  • Think of signatures as digital fingerprints of known malware. Antivirus vendors maintain vast databases containing these signatures, regularly updated with information about new threats.
  • During a scan, the antivirus software compares the code of each file on your system with the signatures in its database.
  • If a match is found, the program flags the file as malware because it shares the same malicious code as a known threat.

2. Heuristic-based Detection:

  • This approach goes beyond simple signature matching. Heuristic analysis examines a file's behavior and characteristics to identify suspicious activity.
  • For instance, the software might look for code that attempts to modify critical system files or establish unauthorized network connections.
  • Heuristics can detect new and previously unseen malware that hasn't been added to the signature database yet.

The Benefits and Limitations:

Signature-based detection is highly reliable for identifying known threats. However, it can't catch entirely new malware variants that haven't been identified yet.

Heuristics, on the other hand, can be more proactive, but they also carry the risk of false positives. This occurs when a legitimate program exhibits behavior similar to malware, triggering an alert.

Why False Positives Happen (and What to Do)

Several factors can contribute to false positives:

  • Overly Aggressive Heuristics: Antivirus software with overly sensitive heuristic rules might flag harmless programs.
  • Outdated Antivirus Definitions: Outdated definitions can cause the software to miss new malware variants while incorrectly identifying benign programs as threats.

Here's what you can do if your antivirus flags a program:

  1. Check the Reputation: Research the program online through trusted sources. Look for reviews from reputable websites and user forums.
  2. Verify the Source: Ensure you downloaded the program from the official developer's website or a trusted app store.
  3. Scan with Another Antivirus: Sometimes, a second opinion from a different antivirus program with a different signature database can be helpful.
  4. Whitelist the Program (with Caution): If you're confident about the program's legitimacy, you can add it to your antivirus software's whitelist. However, only do this if you're absolutely sure about the program's safety.
  5. Contact the Developer: If you're unsure, reach out to the program's developer for clarification. They might be able to explain why the program triggered the antivirus alert and if there's a fix.

Whitelisting a program bypasses your antivirus protection for that specific file. So, only do it as a last resort after thorough research and at your own risk.

Have more questions about how programs detect malware? Ask them away on our social media @protectstar on X or @protectstar-inc on Reddit! 

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