Met a guy the other day who is in the IT software business. We started talking about a case that a friend of mine had me help her with. I have come to the conclusion that she was being scammed and he warned that the document she had me print and then scan for her may possibly be a trojan horse.
Maybe you misunderstood him. A "trojan horse" is a type of malicious software, a subset of what is known generally as "malware".
A document is not software (that is, it is not a program that can run) and it is not malware. However, a document can be a scam. But that would be a bit of social engineering, having little or nothing to do with one's computer other than that it might be how you received the document. A "phishing" scam is a common type of document that you receive, usually via e-mail, that attempts to fool you into doing something that you shouldn't, like sending the bad guys your personal information, or worse, money. But it isn't a program that runs and does malicious things.
We would need more information to tell you exactly what you were dealing with, but from what little you have told us, it isn't malware of any type.
I asked what is the best way to deal with it. He said delete it and anything that was saved. Also highly recommended Kaspersky security software that he has used for years. Is anyone familiar with it?
I'm guessing that this IT person is not a Macintosh expert. You should NEVER get your Macintosh computer advice from someone who only knows Windows. I might even go so far as to say that you should avoid advice from Windows users and experts, as the Macintosh is not Windows and though they look superficially similar, good advice for one platform does not usually carry over to the other.
Kaspersky is a decent (but not the best) commercial anti-virus program, at least with regard to its effectiveness. It identified 94% of the samples in the last comparison test that is on the web that (at least *I* find) believable (there are a lot of shill comparison sites on the Web).
Mac anti-virus testing 2014 - The Safe Mac
(Scroll down to the table of results.)
Unfortunately, Kaspersky as a company is highly suspect, running badly afoul of the U.S. Government in the past:
FCC flags Russian cybersecurity firm Kaspersky as risk to national security
I wouldn't trust it, or have it on my computer.
But that's no big deal. If you look at the table in the link that I just gave you, you will find that Intego's Virus Barrier was the top tested product. The really good news, is that there is a free version:
VirusBarrier Free Edition (free)
Intego VirusBarrier Scanner
If you are feeling paranoid about malware, just download this program and run it and I'm willing to bet that you will find that you aren't infected with anything.
Now, about there being "no viruses for the Macintosh." That's technically true, but incredibly misleading, and a very disappointing thing for anyone who knows anything about the Mac to say.
Technically a "virus" is a self-propagating piece of malware. There are none of those in the wild for the Macintosh. However, the general public considers the terms "virus" and "malware" to be synonymous. A Trojan Horse is not a virus (it doesn't self-propagate, it has to be volitionally disseminated), but it IS malware, and Trojan Horses DO exist for the Macintosh. Here is a list of malware for the Macintosh (this list is dated, though there haven't been a huge number of additions to that list since in was published):
https://www.thesafemac.com/mmg-catalog/
Looking through that list and reading about each example of malware, one can see that just about everything listed either no longer exists in the wild, or the Mac has been hardened against it.
The Macintosh isn't "immune" to malware, and it isn't true that there is no malware for the Macintosh, but there is extremely little malware in the wild to worry about. Of the tens of thousands of users on this discussion list, you will notice that NONE of them are reporting that they have been infected with malware. There just isn't a lot of Macintosh malware going around, and there hasn't been for decades. Also, the Macintosh has several levels of anti-malware software built-in. See:
App security overview
Generally, whatever is going on with your Mac, the answer is just about never that the problem is malware. But you don't have to take my word for it. Have a look at this free video course on Macintosh security:
Do Macs Need Anti-Virus Software?
The Practical Guide To Mac Security: Part 9, Do You Need Anti-Virus Software?
I hope this helps.
