Question

an unauthorised computer programme behaving like an authorised programme thereby concealing what it is actually doing

Answer 1

Please add this as a brainliest answer.....
If a program behaves like this, always understand that your PC is infected with computer virus

Answer 2

This is called trozen horse . When it enters our computer system it's seems like the program is doing something desirable function but at the back it perform it's function of stealing the information or the purpose it is meant for . So trozen horses are always difficult to find as there actions are different from their purpose  .