PUP

A PUP (Potentially Unwanted Program) is software that typically lands on a device bundled with another, legitimately installed application and performs actions the user never knowingly agreed to. A PUP sits on the boundary between an ordinary app and malicious code — it is not always clearly harmful, but it tends to be intrusive, slows the system down and undermines privacy.

How a PUP works

The most common categories of potentially unwanted programs are:

• Adware — floods the screen with ads and injects banners into the browser (see adware).
• Toolbars — attach to the browser and swap the default search engine and home page.
• Browser hijackers — redirect searches to pages of their own.
• Optimizers and "cleaner" tools — scare users with fake errors to push a purchase.
• Data-collecting software — tracks activity and profiles the user without clear consent.

The main infection vector is bundling — attaching a PUP to the installer of free software. During a quick "next, next" install, the user unknowingly accepts extra "offers" hidden in the wizard.

PUPs in practice

From a security standpoint, PUPs are treated as a real risk:

1. Detection — antivirus engines keep a separate "PUP/PUA" detection category you can enable in settings.
2. Removal — uninstall from the operating system, clean out browser extensions, and run a dedicated anti-malware scan.
3. Prevention — download from official sources, use custom installs and deselect add-ons, and keep the OS and browser updated.

Although a PUP is rarely as dangerous as ransomware or an exploit, it can be a gateway to further infections — so it is worth removing as soon as it is detected.