What security measure does a stealth virus typically bypass?

A stealth virus is designed to evade detection by modifying its behavior and cleverly interacting with system operations, particularly those related to the operating system defenses. These viruses can intercept requests made by the operating system to the disk where the virus resides, providing false information to the OS about the state of files, such as indicating that files or processes are legitimate and non-infected when they are not. This capability allows the stealth virus to remain hidden from traditional anti-virus tools that rely on the operating system's reporting.

By effectively hiding from the operating system's defenses, a stealth virus can proliferate and infect additional files without being detected. In contrast, other security measures such as firewalls, which primarily filter incoming and outgoing network traffic, may not have a direct impact on the stealth characteristics of such viruses. Data encryption and user authentication also focus on protecting data and verifying identities rather than specifically counteracting stealth mechanisms employed by a virus. Therefore, the stealth virus's capacity to circumvent operating system defenses underscores its evasion tactics.