Malware
Potentially Unwanted Program (PUP)
Also known as: PUP, Potentially Unwanted Application (PUA)
Definition
Software that is not strictly malicious but installs without clear consent, behaves intrusively, or degrades user experience — for example, bundled toolbars, adware, or aggressive optimizers.
Examples
- Free PDF readers that bundle browser toolbars and change the default search engine.
- "System optimizers" that scare users into buying a paid license.
Related terms
Adware
Software that automatically displays, injects, or redirects to advertisements, often bundled with free software and frequently tracking user behavior.
Greyware
Software that sits in a grey area between legitimate and malicious — annoying, intrusive, or risky, but not clearly designed to harm the user.
Browser Hijacker
Software that alters browser settings without user consent to redirect traffic, change the homepage and search engine, or inject unwanted ads.
Rogue Security Software
Fake antivirus or system-cleaning software that pretends to find threats and demands payment to fix them, while often installing real malware itself.
Trackware
Software that monitors and reports on user activity — sites visited, apps used, keystrokes, or location — typically for advertising, analytics, or stalking.
Scareware
Malicious software or web content that uses fake alarming messages to scare victims into installing junk software, paying for fake services, or calling fraudsters.