Q: It’s been a while, but this digitally challenged senior citizen needs your wise counsel again. I've been very diligent in following your instructions about not clicking on suspicious things, but I was totally duped two days ago. I got a "secured Google document" from a friend. I don't do Google docs, so I downloaded the program to read it. Bad mistake, but it was so slick I still didn't get suspicious. The document was a reprint of four pages of my ancestors back five generations, and the sender was a trusted genealogist I correspond with regularly. I already had the documents, and I just wondered why she sent it to me again, but didn't bother to ask. Well, in about 12 hours, I started to get queries from EVERYONE in my address book!

I have changed my password for AOL, but am wondering if there is a hidden program lurking that might be stealing other passwords, personal and financial information in my computer.

– Franklin B., Shalimar

A: Aside from not clicking it in the first place, quickly changing your password was probably the best thing you could have done, Franklin. Based on the fact that you were getting emails from everybody in your address book, it sounds like someone had your password, and was using their access to your account to proliferate malware-laced SPAM. Changing it very likely locked them out and put an end to it – this time.

Based solely on the information you supplied, it’s impossible for me to gauge the extent of the damage or infiltration done to your computer. Do you have a “hidden program lurking” on your system? If you’re talking about malware, statistics say that there is a good chance of it. There have been recent reports that over 30 percent of the computers operating worldwide have some type of malware infestation. The authors of such trash software are releasing new ones every day. Is it any wonder our antimalware software can’t keep up, and occasionally lets one slip through?

I’d like to comment on the vector by which you believe your PC was compromised. Obviously, you’ve been paying attention to my warnings, and have trained yourself not to open things that look strange, or come from people you don’t know. But in this case, you stumbled on a type of threat that is a little harder to detect – email that appears to come from a trusted source. I routinely receive email from the likes of Amazon, UPS, eBay, and other sources that I normally trust, but which are phony attempts to get me to do what you unfortunately did: run an attachment that ends up being malware. So, it’s time to learn that it’s no longer enough to be wary of email from strangers. You now must beware of email that at least appears to come from friends. One hallmark of this kind of threat is that most of them want you to open an attachment. This is the virus payload that is going to infect you. If you receive an attachment that you’re not expecting – even if it’s from a friend – don’t click it or open it. Don’t even preview it within your mail program.

If you just absolutely feel compelled to delve into these attachments despite my warnings above, let me give you a few other tips that may help you convince yourself to leave them alone. One trick that I often see in such SPAM is tacking on a second file extension on to a legitimate looking filename. An email attachment might have a name like Invoice.docx.exe. At a casual glance you might think that’s a Microsoft Word document. But only the last extension is valid, so this would actually be an executable program. Speaking of which, we all know that only files that have extensions like .exe or .com can contain code that can run on our PC, right? Wrong. Many software applications, including the entire Microsoft Office suite and Adobe Acrobat support the embedding of macro functions within a document. These are usually automatically executed when the file is opened, leaving a perfect vector for malware infestation.

You can have all the malware scanners, antivirus/antispyware programs, and ad blockers in the world on your PC, but the most important part of your PC’s protection is YOU. Learning what not to click on is your first, best defense in the battle against malware infestations.

To view additional content, comment on articles, or submit a question of your own, visit my website at ItsGeekToMe.co (not .com!).