Polymorphic Malware: The Shapeshifting Code

Mutation as a Defense

In biology, viruses mutate to survive. In cybersecurity, polymorphic malware does the same. It uses encryption and code obfuscation to change its binary signature while keeping its malicious payload intact.

How It Works

• Encryption: The main body of the virus is encrypted with a variable key.
• Decryption Loop: A small piece of code (the decryptor) runs first. This loop is randomly generated for each infection.
• Result: Two files of the same virus look completely different to signature-based scanners.

Beyond Polymorphism: Metamorphic Malware

Metamorphic malware goes a step further by rewriting its own code—swapping instructions, inserting junk code, and reordering functions—without using encryption. It is effectively a new program every time.

Detection Strategies

• Heuristics: Looking for suspicious characteristics rather than exact matches.
• Behavioral Analysis: Monitoring what the program does (e.g., trying to modify system files) rather than what it looks like.
• Threat Intelligence: Blocking the C2 servers that control the malware. Check suspicious connections with our Domain Scanner.

Related Reading

• What is a C2 Server?
• Ransomware Detection Guide
• Industrial Control Systems Malware
• Infostealer Malware Trends
• EDR Response Guide