Computer viruses have come a long way from the floppy-disk threats of the 90s. Today's malware is faster, smarter, and harder to spot — and in 2025, the threat landscape changed dramatically. Here's what you need to know, and what to do if your PC is already infected.
A computer virus is malicious software — usually called "malware" — that is designed to damage, disrupt, or gain unauthorized access to your computer system. Like a biological virus, it can copy itself and spread to other files, programs, or even other computers on your network.
But here's the thing: the word "virus" has become a catch-all term that most people use to describe any kind of malicious program. Technically, a virus is just one type of malware. Ransomware, spyware, trojans, and infostealers are all different animals — but they're all equally dangerous, and in 2025, these threats grew significantly more sophisticated.
A traditional virus works by attaching itself to a legitimate program or file. When you run that program, the virus executes alongside it — often silently. It may then copy itself into other files, slow your system down, corrupt data, or open a backdoor for an attacker to access your machine remotely.
Modern malware often skips this self-replication step entirely. Ransomware, for example, doesn't need to spread to do damage — it just needs to find your files and encrypt them. Infostealers don't spread at all; they quietly harvest your passwords, browser cookies, and financial data, then send it all back to the attacker before you even notice something is wrong.
The common thread in nearly every case: the attacker needs a way in. That entry point is almost always a phishing email, a malicious download, an outdated piece of software with a known vulnerability, or — increasingly in 2025 — a compromised credential that lets an attacker simply log in rather than hack in.
The malware landscape grew significantly in scale and sophistication over the past year. Here's what the data shows.
People use "virus" as a shorthand, but there are several distinct types of malicious software — each with different goals and behaviors.
Attaches itself to a legitimate file or program and spreads when that program is executed. Can corrupt files, slow your system, and copy itself to other devices. Less common than it used to be, but still exists.
Encrypts your files and demands payment to restore access. Ransomware was involved in 44% of all data breaches in 2025. Even small businesses and home users are targeted. Paying the ransom does not guarantee file recovery.
Silently harvests your passwords, browser cookies, saved credit cards, and session tokens — then transmits everything to an attacker. Over 1.8 billion credentials were stolen by infostealers in just the first half of 2025 alone.
Disguises itself as legitimate software — a free game, a PDF reader, a fake system update — and installs malicious code when you run it. One of the most common infection vectors, especially via email attachments and shady download sites.
Monitors your activity, keystrokes, browsing history, and sometimes your webcam or microphone without your knowledge. Often bundled with free software. Designed for surveillance — sometimes by a jealous partner, sometimes by a criminal.
Forces unwanted ads into your browser, redirects your searches, and changes your homepage. On its own it's a nuisance — but adware often opens the door for more dangerous malware by exposing you to malicious ad networks.
Unlike a virus, a worm doesn't need you to run anything — it spreads automatically across networks by exploiting vulnerabilities. One infected machine on a home or business network can quickly compromise every other device on it.
Buries itself deep in the operating system to hide its presence from antivirus tools and even the system itself. Rootkits are designed for long-term, undetected access. Removing them often requires advanced tools or a full OS reinstall.
Uses your computer's processing power to mine cryptocurrency for the attacker — without your knowledge. Your PC slows down, your electricity bill goes up, and your hardware runs hot. SonicWall recorded over 1 billion cryptojacking incidents in recent years.
Some infections are obvious. Others are designed to stay hidden for weeks or months. Here are the signs to watch for — and if you're already seeing several of these, read our full guide on signs your computer may be infected with malware.
The delivery methods haven't changed dramatically — but they've gotten a lot more convincing, largely because attackers are now using AI to make their scams and lures much harder to spot.
Phishing — fake emails designed to trick you into clicking a link or opening an attachment — remains the single most common entry point for malware. In 2025, successful phishing attacks increased by 400% compared to prior years, largely because AI tools allowed attackers to eliminate the spelling errors and awkward phrasing that used to be the telltale signs of a scam. A phishing email today can look nearly identical to a message from your bank, your boss, or UPS.
Free software from unofficial sources, cracked games, fake browser extensions, and counterfeit utility apps are all common malware delivery vehicles. In 2025, attackers published over 15,000 malicious packages to open-source software registries — targeting developers and businesses who rely on shared code libraries.
Every piece of software on your computer has vulnerabilities that get discovered over time. Software companies release patches to fix them. If you're running an outdated version of Windows, an old browser, or haven't updated your router's firmware in years, attackers can exploit those known holes without you clicking anything at all. This is why keeping software updated isn't optional — it's foundational.
This is a major shift in how attacks work in 2025 and beyond: attackers are logging in rather than breaking in. If your username and password have been leaked in a data breach — and billions of credentials are bought and sold on criminal marketplaces — an attacker may simply use them to access your email, your cloud storage, or your business accounts. No virus required. This is why password reuse is so dangerous, and why two-factor authentication matters.
Plugging in a USB drive you found in a parking lot, or one handed to you at a trade show, is still a real risk. Worm-style malware like "Raspberry Robin" specifically targets removable media as a propagation method. Never plug in a USB drive you didn't purchase yourself from a trusted source.
By 2025, AI had become a dual-edged tool in cybersecurity — used by defenders to detect threats faster, and by attackers to create more convincing phishing lures, generate malware code, and automate the early stages of network intrusion. CrowdStrike reported an 89% increase in attacks by AI-enabled adversaries in 2025. The fastest recorded attacker "breakout time" — the time between initial access and moving to another system on your network — dropped to just 27 seconds.
The fundamentals haven't changed — but they matter more than ever given how fast threats move in 2025.
Windows updates, browser updates, and app updates patch known security holes. Turn on automatic updates and don't keep clicking "remind me later."
Never reuse the same password across multiple sites. Use a password manager. Enable two-factor authentication on email, banking, and any important account.
Windows Defender (built into Windows 10/11) is solid for most home users. Malwarebytes is a reliable addition for on-demand scans. Avoid fake "PC cleaner" tools — many are malware themselves.
Don't click links in unsolicited emails. Go directly to websites. Verify unexpected invoices or requests by calling the person directly. If it creates urgency, treat it as suspicious.
The best defense against ransomware is a backup that attackers can't reach. Use an external drive (kept offline) or a reputable cloud backup service — ideally both. Test your backups periodically.
Only install software from official sources — the Microsoft Store, the Apple App Store, or the developer's own website. Avoid cracked software, pirated content, and "free" tools from sites you don't know.
First: don't panic. Don't pay anything. Don't call a phone number that appeared on your screen (those are almost always scams). Here's what to actually do:
Malware is the broad category — it stands for "malicious software" and includes viruses, ransomware, spyware, trojans, adware, and more. A virus is a specific type of malware that copies itself and spreads to other files. Most people use "virus" to mean any malware, which is fine for everyday conversation — just know that not all malware actually self-replicates like a traditional virus.
Yes. The old "Macs don't get viruses" idea is outdated. In 2025, malware campaigns increasingly targeted macOS users alongside Windows — sometimes in the same campaign. Mac users face adware, infostealers, fake apps, and browser hijackers. macOS has good built-in protections, but it's not immune, and running reputable security software is still a good idea.
Smartphones can get malware, though it works differently from a traditional PC virus. Android devices are more commonly targeted — especially through fake apps downloaded outside the official Play Store. In 2025, Android banking trojans became significantly more sophisticated, with some capable of mimicking human typing behavior to evade detection. iPhones are harder to infect but not completely immune, especially if you've jailbroken the device.
Not necessarily. Paying gives you no guarantee — attackers have no obligation to send a working decryption key after receiving payment. Law enforcement and cybersecurity organizations universally advise against paying ransoms, both because it doesn't guarantee file recovery and because it funds criminal operations. If you're hit with ransomware, contact us before doing anything. Depending on the ransomware strain, data recovery may be possible without paying.
For most common infections — adware, browser hijackers, basic trojans — we typically have computers cleaned and back to normal within a day or two. More complex infections, rootkits, or ransomware situations can take longer depending on what we find. We'll give you an honest estimate when you drop off. We don't start work without telling you what we found and what it'll cost to fix.
We make every effort to preserve your data during virus removal. Most malware removal does not require wiping the drive. In cases where a full reinstall is the safest option, we'll discuss that with you first and back up whatever data we can recover before proceeding. We won't wipe anything without your knowledge and approval.
For most home users, yes — Windows Defender (built into Windows 10 and 11) combined with occasional Malwarebytes scans provides solid baseline protection. Where things break down is user behavior: even the best antivirus can't protect you if you click a convincing phishing link and hand over your password. Good habits matter at least as much as the software you run.
Yes. We provide small business IT support to companies across central New Jersey — including network assessment, malware removal, and security hardening to reduce the risk of future infections. Give us a call at (908) 428-9558 to discuss what you're dealing with.
Drop it off at our Somerville, NJ shop — no appointment needed. We'll diagnose the problem, explain what we find, and get your machine cleaned up and secure.
📞 (908) 428-9558One location, drop-off only. Dave's Computers has one location at 75 N Bridge St, Somerville NJ 08876. All virus removal and repairs are performed at our Somerville shop. We do not offer on-site or in-home service.