What technique allows a virus to evade detection by changing its code?

Polymorphic techniques allow a virus to evade detection by altering its code while maintaining the original functionalities and objectives of the malware. This is achieved through various methods, such as changing the virus's binary code every time it replicates or spreads. By modifying its appearance, a polymorphic virus can effectively avoid signature-based detection systems, which rely on identifying known patterns of malicious code. This makes it particularly hard for traditional antivirus solutions to identify and neutralize the threat, as the signature used for detection becomes obsolete with each iteration of the virus.

In contrast, stealth techniques refer to methods that the malware uses to hide its presence or reduce its visibility on the system but do not fundamentally alter its code structure. Disabling usually relates to actions taken by malware to disable security features or software rather than changing the malware itself. Encryption involves encoding data to protect it from unauthorized access, which can be a method used in some malware, but it doesn’t inherently change the actual code of the virus. Thus, polymorphic is the specific technique that directly refers to the code-changing capability for evasion of detection.