PUP vs. PUM

Introduction

Concept: PUP and PUM are classifications used by Antivirus vendors for things that are not technically viruses but are annoying, intrusive, or dangerous to the user's privacy.
The Key Word: "Potentially."
- Antivirus companies use this specific word for legal reasons. Usually, the user (accidentally) clicked "I Agree" to install these things, so the AV cannot call them "Malware" without risking a lawsuit from the software vendor.

"The Uninvited Guest"

Definition: A software application that you likely didn't want, but it installed itself anyway (usually bundled with free software).
Behavior:
- Adware: Showing aggressive pop-up ads.
- Spyware: Tracking your browsing history to sell to advertisers.
- Bloatware: Slowing down your PC with useless features.
Example: You download a free "PDF Converter." During installation, you clicked "Next" too fast and accidentally installed the "Ask Jeeves Toolbar" or a "Weather Checker." That toolbar is a PUP.

"The Unauthorized Change"

Definition: A change made to your computer's System Settings (usually the Windows Registry) that lowers your security or alters your workflow.
Behavior: It is not a file; it is a configuration change.
Examples:
- Browser Hijack: Your homepage changed from Google to MySearch123.com.
- Security Disabled: The Windows Task Manager or Registry Editor has been disabled (DisableTaskMgr = 1).
- DNS Hijack: Your DNS settings were changed to route traffic through a rogue server.

Feature	PUP	PUM
What is it?	A File / Application.	A Setting / Registry Change.
Origin	Bundled installers ("Free Download").	Malware or PUPs making changes.
Risk	Medium (Privacy/Performance).	High (Security/Usability).
Action	Quarantine / Uninstall.	Revert to Default.