Can your computer become infected with a virus via email? It absolutely can. I had one of the worst weeks of my career due to a virus delivered over e-mail. But the good news is, it’s preventable. You can take simple measures to make it much more difficult, if not impossible, to catch a virus via e-mail.
Let me tell you a story
It was 2001. I’d just gotten to work and for some reason I decided to check my e-mail before going to the breakroom for coffee. One of the messages in my inbox was from a manager. She was married and more than twice my age and she tolerated me. Deep down she probably thought I was a bit of a punk. What’s that have to do with anything? The subject line said “I love you.”
Now, the subject line hadn’t registered. I saw it was e-mail from a manager, so I opened it. The body of the message read, “Kindly check the attached love letter coming from me.” Or something to that effect. It didn’t sound like her at all. There was an attachment, loveletter.vbs. I opened it. But I opened it in Notepad. I was more than a decade from being a CISSP, but I knew to examine unexpected attachments.
Long story short, I’m no VB programmer but I didn’t like what I saw about 13 lines in, when I saw the code was trying to edit the system registry. I made a couple of phone calls and quickly found out it was indeed a virus, and they were working on deleting it from the mail servers, but an unknown number of computers were already infected. One of our developers had figured out what files to delete to clean it up.
By the end of the day, we knew hundreds of computers had been infected. I ended up leading some of the cleanup efforts. Not because I was a manager, but because I could quickly teach anyone who was interested in helping how to delete those files, and if that didn’t work, they could leave the computer for me and I would figure it out from there.
I gave up alcohol in 2003, but I drank quite a bit that week.
I’ve had other run-ins with viruses in my career but that one was the most memorable.
How a computer can become infected with a virus via e-mail
First of all, those messages that say not to open a message with a certain subject line are almost always hoaxes. A virus has to have something more than just text to sit in. Generally you have to open an attachment to infect the computer.
But if you open an infected attachment, the game’s over. Your computer can get infected at that point, then do things you don’t want it to do. Most are more subtle than Love Letter of 2001 was.
If someone ever paid me to hack their network and then tell me how I did it, I would start by sending an infected e-mail attachment to someone who would open it. Applying for a job and sending a resume to HR ought to do the trick. Opening e-mail from strangers is their job.
How to stop a computer from becoming infected with a virus via e-mail
Using cloud-based e-mail is a good first line of defense. I’ve had people take me to task for using Gmail, but Google does a good job of keeping my inbox virus-free.
The second line of defense is having antivirus software. Windows comes with good-enough antivirus software, so it’s fine to use that.
The last, and most important line of defense is to keep your software up to date. Adobe Acrobat and Microsoft Word attachments are good for hiding malicious payloads in, so make sure you let Adobe Reader and Microsoft Office update when they want to. If it seems like they want to update every other month, you’re probably not imagining things. It’s a hassle, but those updates keep your computer much safer.
I lied. There’s a fourth line of defense. I don’t even open unexpected e-mail from strangers. And I have to have a really good reason to open an unexpected e-mail attachment from someone I know. I miss some jokes that way, but It keeps me from getting viruses.