| Activity hidden from user | May collect information | can copy itself | Takes control over computer | Lives on operating Systems | Target | |
|---|---|---|---|---|---|---|
| Trojan | Yes | Yes | No | Yes | predominantly Windows | user-mode applications, kernel |
| Virus | Mostly not. User normally see something abnormal | Yes | Yes | No | predominantly Windows | user-mode applications, kernel |
| Backdoors | Yes | Yes | No | Yes | predominantly Windows | user-mode applications, kernel |
| Spyware | Yes | Yes | No | No | predominantly Windows | user-mode applications |
| Rootkit | Yes | Yes | No | Yes | All included Unix, Linux and MacOS | firmware, a hypervisor, the kernel, user-mode applications |
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