Malware
Non-Resident Virus
Also known as: Direct-action virus
Definition
A virus that does not stay in memory after execution; it searches for and infects target files only while the host program runs, then exits.
Examples
- Classic file infectors like Vienna that scan a directory and infect .COM files.
- Direct-action viruses that activate only when their carrier executable is launched.
Related terms
Computer Virus
Malicious code that inserts copies of itself into other programs or files and executes when the host is run.
Resident Virus
A virus that installs itself in memory so it can run continuously and infect files or processes long after its host program has exited.
Trojan Horse
Malware that disguises itself as a legitimate program to trick users into running it, delivering a hidden malicious payload.
Polymorphic Malware
Malware that changes its on-disk appearance — typically via re-encryption or packing — for each infection, while keeping its core logic intact.
Stealth Malware
Malware specifically engineered to evade detection by users, security tools, and forensic investigators through hiding, mimicry, and anti-analysis tricks.
Malware
Any software intentionally designed to disrupt, damage, or gain unauthorized access to computers, networks, or data.