IT security and data protection firm Sophos is warning computer users to be cautious following the discovery of a widespread spam campaign that is promising cash in return for completing a McDonald's customer satisfaction survey. The emails, claiming to be sent by 'McDonald's Survey Department' and with the subject line 'McDonald's Customer Survey' direct recipients to the survey that poses questions on McDonald's food.

Once the survey has been completed, computer users are asked to provide a raft of personal information, including their credit card number and security code, so that they can receive a $90 payment for taking the time to complete the questions.

"Exploiting online surveys is a popular way for scammers to make money as legitimate customer satisfaction surveys are increasingly common", said Graham Cluley, senior technology consultant at Sophos. "Although it's not unusual to be offered a reward or the chance of a prize for completing an online survey, a legitimate questionnaire will never ask you to part with your card details."