My mother-in-law bit on a fake email ("Your USPS package...") sent to her AOL account and opened the attachment with her iMac. She's on 10.5. She called us shortly after she realized that the attachment wasn't opening. No symptoms yet. What is the impact? What diagnostic/recovery/protection steps should I take? (other than making sure in the future she's up-to-date with her operating system and has an antivirus)
No antivirus. There's a partial backup but it's on a hard drive that's connected; can I trust it?