TROJ_CRYPCTB.NSA can be categorized as a kind of trojan which is very good at infecting . It can enter any pc by means of porn websites, spam email, freeware installer and fake software update links. Also, it can infect all kinds of system, including windows xp, windows 7, windows 8, vista, linux, and so on. It is notorious for its infection but it is seldom detected by users since its excellent elusive nature.
When TROJ_CRYPCTB.NSA targets on your pc, it is able to control the whole operating system. It will change its settings and disable the functions rejecting itself. In the same time, it will bring in tens of thousands of virus on your pc. So many people think it is more dangerous than the virus.
And the significant functions of TROJ_CRYPCTB.NSA is to make your documents or files locked with unknown password or some programming. It is of course not just for fun. It aims at money from you. When you have found that some of your doc. which you desperately need, you will be eager to solve it just with several hundred dollars. But when you consider the whole scam in retrospect, you may blame yourself for the carelessness.