What is a common technique used by malware to evade detection by antivirus software?

A common technique used by malware to evade detection by antivirus software is known as "polymorphism." This technique involves constantly changing the code or structure of the malware, making it difficult for antivirus programs to recognize and detect it. Here are the steps involved in this technique:

1. Code Mutation: Malware authors use various methods to modify the code of the malware, such as adding junk code, changing variable names, or altering the order of instructions. This makes the malware appear different each time it is executed.

2. Encryption: Malware can be encrypted using different algorithms, making it unreadable to antivirus software. The malware is decrypted at runtime, allowing it to execute its malicious activities.

3. Obfuscation: Malware authors use obfuscation techniques to make the code more complex and difficult to understand. This can involve techniques like code splitting, dead code insertion, or using anti-analysis tricks.

4. Dynamic Linking: Malware can dynamically load external libraries or modules at runtime, making it harder for antivirus software to detect its presence. This technique allows the malware to hide its malicious activities within legitimate processes.

5. Fileless Malware: Some malware operates entirely in memory without leaving any traces on the disk. This makes it challenging for antivirus software to detect and analyze the malware.

By employing these techniques, malware can evade detection by antivirus software and continue to infect systems without being detected.