Protection is provided to prevent a computer user from unintentionally giving away sensitive data (e.g., security credentials, credit card number, PINs, personal data, or bank account number) to an illegitimate or unintended entity by means of a client application capable of communicating the sensitive data across a network to other computer users. To provide the protection, user input is monitored to detect a user entry of the sensitive data into the client application for communication to other users. When such an entry occurs, action is taken to reduce the likelihood of an unintentional giveaway of the sensitive data or to reduce the effects of an unintentional giveaway.