Proprietary software, nonfree software, is software that doesn't respect users' freedom and community. The developer or owner has power over its users. That in itself is an injustice, but it often leads to further injustice.
Power corrupts, so the program's owner is tempted to put malicious functionality into the program — that is, to make it malware. Malware means software whose functioning mistreats the user. This page gives examples of widely used proprietary programs that are known to be malware.
- Proprietary back doors
- Proprietary insecurity
- Proprietary sabotage
- Proprietary surveillance
- Digital Restrictions Management
The way to avoid these forms of abuse is by insisting on free (freedom-respecting) software. Since free software is controlled by its users, they have a pretty good defense against malicious software functionality. Users of proprietary software are defenseless.