A potentially unwanted program (PUP) is software that the user may not want on the device, such as bundled toolbars, browser hijackers or aggressive “optimisers”, even though it is not clearly malware.
How PUPs work
PUPs sit in a grey zone between legitimate software and malware. They usually arrive with the user’s technical consent – a pre-ticked checkbox in an installer, a long licence agreement or a “recommended” offer bundled with free software. Typical categories include:
- Browser hijackers and toolbars that change the homepage and search engine.
- Adware that shows extra advertisements.
- System optimisers and “registry cleaners” that exaggerate problems to sell a licence.
- Bundlers – installers that add several third-party programs at once.
- Cryptocurrency miners and remote tools installed without a clear explanation.
Microsoft uses the term “potentially unwanted application” (PUA), and Microsoft Defender can block such apps when PUA protection is enabled.
Why PUPs matter
Because their developers can argue that users agreed to install them, PUPs avoid the legal risks of malware while still slowing systems, collecting data and exposing users to shady ads. Some PUPs drift into spyware territory or open the door to further infections. PUPs are also frequently bundled with cracks and pirated software, which makes them a common first step towards real malware.
How to avoid PUPs
- Download software from the developer’s official site or an official app store.
- Choose custom installation and untick all extra offers.
- Enable PUP or PUA detection in your antivirus; it is sometimes off by default.
- Regularly review installed programs and browser extensions, and remove anything you did not knowingly install.
