A polymorphic virus is a type of computer virus that changes its code structure with each infection, making it difficult to detect and remove.
Here's how it works:
1. Encryption: The virus's core code is encrypted using a unique key for each infection. This obscures the original code, making it difficult for antivirus software to recognize it based on known signatures.
2. Mutation: The virus uses a special algorithm to alter its own code during each infection, creating a slightly different version. This makes it hard to detect using traditional antivirus methods that rely on identifying specific code patterns.
3. Decryption: Once the virus infects a new system, it uses the stored key to decrypt its code and execute its malicious payload.
Why are they so dangerous?
* Evading detection: The constantly changing nature of polymorphic viruses makes it difficult for antivirus software to keep up.
* Difficult removal: Traditional antivirus methods that rely on pattern matching may be ineffective against these viruses.
* Persistent infection: The ability to change its code allows polymorphic viruses to spread rapidly and persist even after a system is "cleaned."
Examples:
* VBA.Dofoil.B: This virus was known for its ability to encrypt and decrypt its code, making it challenging to detect.
* CIH: This virus used a specific type of polymorphism to alter its code and evade detection.
Protection against polymorphic viruses:
* Use strong antivirus software: Choose software that uses advanced detection methods like behavioral analysis and heuristic scanning.
* Keep your software up-to-date: Regularly update your operating system, antivirus software, and other applications.
* Be cautious about opening attachments and clicking links: Be wary of suspicious emails and websites.
* Backup your data regularly: This helps you recover from an infection if it occurs.
In summary: Polymorphic viruses are a highly dangerous threat because they are constantly evolving and difficult to detect. Taking proactive steps to protect your computer and staying informed about the latest threats is crucial for staying safe.
