[patman76]

The best way to protect yourself on a Mac is not to use an administrator account for day to day running.

You should create a user account for every day usage. Only use the administrator account to install system wide applications and to apply system updates.

This will protect you from such malware, as the user account will need administrator authorisation to run any hidden apps/scripts that try to modify the system - any jpeg that requires authorisation to modify anything should set off the alarm bells!