Scareware has taken on a human face. Criminals posing as computer security engineers are having success in calling victims at home and stealing their money, according to a survey issued Thursday by Microsoft. Fifteen percent of 7,000 computer users polled in the United States, Canada, U.K. and Ireland said they have been been contacted by a phone scammer, and 22 percent of those were tricked into following the fraudsters’ directions, which included giving them remote access to a computer or providing credit card information. Seventy-nine percent of those suffered a financial loss as a result. Victims were out an average $875 in the United States, the survey found.