Worms vs. Viruses: What’s the difference?

Worms, viruses, bots, oh my! Such names sound less like monikers for malicious software than characters in a sci-fi novel. Despite their fictional-sounding names, the monetary damage these types of malware can cause to computers and data is very real. Studies put the global cost of ransomware attacks for 2017 between 1 and 3 billion dollars.

Most types of malicious software (aka malware) work differently, but all have the same function: to install unwanted software on your computer or network for malicious purposes ranging from simple annoyance to corporate espionage.

Two of the most common forms of malware are worms and viruses. Knowing how they work can limit the damage of a malware attack sooner and help avoid infection altogether.

Spreading the Word Doc

Worms and viruses differ in two main ways: how they spread or “replicate” and their level of autonomy. To function, viruses need a host file (e.g., a Word document) or a host program (e.g., that free PDF splitter you downloaded). To replicate, viruses need humans to send them through emails, messages, attachments, etc. They can’t do this on their own.

Worms are viruses that can replicate themselves, emailing themselves to other computers and networks without help from pesky humans. A worm’s autonomy tends to make it more aggressive or contagious, while a virus may lay dormant for years waiting for a user to open an infected file. To use a cinematic analogy, worms are more like predators, viruses are more like aliens.

How viruses replicate

Computer viruses are transmitted like biological ones. For example, the common cold spreads through person-to-person contact. We pass our cold germs to other people through coughs and sneezes. Unsuspecting victims breath in our virus spray and presto! We’ve just replicated the virus to them. The point: It takes a human action (i.e., coughing and sneezing) to replicate a virus.

We replicate computer viruses by sending (sneezing) infected attachments through emails, instant messages, etc., to other users. Like us, they unknowingly download and open the attached file. Most recipients will open these attachments because they trust us. Replication of the virus took a human action and a little gullibility.

Social engineering

Social engineering is a way of tricking people into spreading malware to others. Hackers use our own assumptions and confirmation bias to fool us.

For example, when we visit our bank’s website, we usually first look for the most recognizable features: company name, logo and the familiar layout of the page. All of these features tip us off that we’re in the right place. Instead of applying a more critical eye, we quickly compare what we see to what we expect. When those basic expectations are confirmed, we click ahead.

Everyday, hackers create malicious copies of legitimate websites and emails to steal our private credentials. These digital fakes don’t need to be perfect copies either, just close enough to match our expectations. That’s why it’s best to avoid clicking email links to common websites and instead use a browser bookmark so you always know you’re in the right place.

Even a worm will turn

Worms are actually a subclass of virus, so they share characteristics. They also are passed through files like attachments or website links, but have the ability to self-replicate. Worms can clone and transmit themselves to thousands of other computers without any help from humans. Consequently, worms tend to spread exponentially faster than viruses.

Worms have this viral superpower in part because they don’t rely on a host file like a virus. While viruses use these files and programs to run, worms only need them as disguises to sneakily wiggle into your computer. After that, the worm runs the show. No more host files or social engineering required.

How to protect yourself

Even though worms and viruses are different, you take similar precautions to avoid them.

Avoid opening unfamiliar messages and attachments

Social engineering is powerful and preys on our assumptions and familiarity, but you can fight it by paying more attention to your online interactions. Inspect emails closely. Phishing emails usually have telltale signs they’re scams. Most importantly, never open an email attachment from an unknown source. If you can’t confirm the source, delete the attachment. One moment of satisfying your curiosity isn’t worth the risk.

Avoid non-secure web pages

Non-secure websites don’t encrypt how they talk to your browser like secure ones do. It’s easy to identify websites that are non-secure. They start with HTTP in their URL address. Try to visit only secure sites that start with HTTPS. The ‘s’ stands for ‘secure’. Browser plugins like HTTPS Everywhere can make searching only HTTPS sites easier.

Update your operating systems

Hackers love to find security holes in operating systems like Windows. It’s a game of cat and mouse played with software engineers who constantly test, identify and patch ways of infiltrating their own software. The result of their efforts is the security update. Updating your OS applies those patches as soon as they’re released, increasing your protection level. Set your system to auto-update.

Be picky about your programs

Like operating systems, individual apps on your devices also need updating – and for the same reason. Aside from updating them, you should also decide whether you even need them at all. Remember, viruses need host files and programs for execution and disguise. Decide whether you actually need the app, or if you already have it, how often you use it. The more apps you have, the more updates. The more updates, the more opportunities for a security breach or infection.

A couple of programs you will want to give special attention to are Adobe Flash and Acrobat Reader. Both are popular targets for cyber criminals. If you don’t use them, uninstall them.

Get antivirus protection

The easiest and most effective action you can take to protect yourself from worms and viruses is to get a total antivirus protection plan. Antivirus software can’t be manipulated by social engineering tricks. It never assumes anything. It scans every file you open and every program you run for viruses and worms. Good ones do this in real time.

Every worm and virus discovered gets assigned a ‘signature’, a unique indicator that says “this is a virus!” Antivirus software keeps a list of those signatures and compares them to all of the data coming through your system.

You now understand the differences between worms and viruses, how they spread and where they hide. Be more critical the next time you open an unfamiliar email or visit a familiar website. Following these tips and getting antivirus software is the best way to avoid malware.