CyberGuard dictionary / Malware
Computer Virus
A computer virus is malicious code that attaches to another file or program and replicates when that host is executed.
In simple terms
Unlike a standalone worm, a virus depends on a host file or program being run to spread its code.
Technical explanation
A virus inserts or appends code to executable content and may copy itself to additional hosts or files after execution. Its payload can be separate from its replication behavior, and modern malware may combine several techniques.
Replication requires an infected host file or program to run, unlike a worm that can propagate independently across a network. The malicious payload may corrupt data, install other code, or do little beyond copying itself.
Examples in practice
A user opens an infected executable, which then modifies other local programs so they carry the same malicious code.
A shared executable is copied to another workstation and run there, spreading the infection to more local files. The response team quarantines the file and checks copies on shared drives.
Why it matters
Knowing the replication method helps responders identify all affected files instead of deleting only one sample.
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Sources and further reading
Published 2026-10-15 · Last updated 2026-10-15 · CyberGuard editorial content. Source links provide context; they do not imply endorsement.