TrustNinja is a fake security software, or a rogue antispyware. TrustNinja is a clone of
KeepSave, another fake security software.
TrustNinja can infect a PC with the help of Trojans, shady websites advertising misleading spyware scanners or directly from the TrustNinja website:

If your PC is infected with TrustNinja, it will run a system scan every time windows is booted and report numerous infections. These reports are falsified, the infections are greatly exaggerated or completely fake. TrustNinja shows these false scan results and insists the user purchase the full version of the software to remove the infections.

Continual pop ups and system warnings will also be displayed showing phony alerts and warnings of infections urging users to buy the software. Do not fall for the TrustNinja scam, buying this software will not stop the warnings and pop ups, it will not remove infections from your PC or protect it from future infections.