Malware on macOS: The everyday clues most people miss

When a Mac suddenly feels slow, crashes more than usual, or starts showing strange pop-ups, something is off. Sometimes, it’s a normal software issue, but malware can cause the same kind of chaos. Below are the most common signs to watch for, plus simple ways to verify what’s really happening.

Frequent system crashes and slowdowns

Random freezes, spinning beach balls, apps quitting unexpectedly, or long boot times can happen for normal reasons, such as low storage, buggy updates, or a failing drive. Malware can cause similar symptoms by running hidden tasks in the background, injecting itself into apps, or constantly contacting remote servers.

Rapid battery drain

Battery drain often points to heavy background activity. A legit cause might be a browser with many tabs, Spotlight indexing, or a video call. Malware can drain power by mining crypto, running ad scripts, or constantly uploading data.

Unfamiliar processes running

Every Mac runs many background services, so “unknown process” doesn’t always mean “bad.” A normal process is usually signed by Apple or a known developer, behaves consistently, and matches installed software. Malware often tries to blend in with harmless-sounding names like “Updater,” “Helper,” or “Security.”

To verify whether a process is legitimate, go to Activity Monitor and double-click on any suspicious processes to view details. Take a moment to review the name and any related information to decide if it matches something you intentionally installed. If it looks unfamiliar or oddly named, make a note of it.

Next, check which programs are set to open automatically when your Mac starts up. Go to System Settings > General > Login Items and review the list carefully. Remove any apps you don’t recognize or no longer use. Programs that automatically relaunch every time you reboot (especially ones you didn’t approve) deserve closer attention.

Pop-ups and fake alerts that try to scare you

Scareware is built around pressure. Messages claim your Mac is “infected,” “at risk,” or “locked,” then push you to call a number or install a tool. Legit macOS security alerts don’t typically include phone numbers, flashing banners, or urgent countdowns.

Increased network activity

Unusual internet activity can be a serious warning sign because many types of malware quietly communicate with outside servers. That connection might be used to send out data, pull in more unwanted software, or load aggressive ads. Some background traffic is completely normal, such as iCloud syncing or apps updating, but it usually comes from apps you recognize.

To check what’s happening, open Activity Monitor and click the Network tab. Sort the list by Data Sent or Data Received to see which apps are using the most internet data. If something unfamiliar is near the top while you’re not actively using it, this could be a sign of malware.

Modified security settings you didn’t change

Malware sometimes tries to weaken defenses by turning off protective features, adding device profiles, or pushing you to allow system extensions. A “modified settings” warning should be treated seriously if nobody on your team or household made changes.

To check, open System Settings > Privacy & Security and review any recent security messages or newly allowed apps. Look for a Profiles section as well (it may appear within Privacy & Security). If you see a profile you don’t recognize, investigate it further or remove it. Unknown profiles can quietly change how your Mac connects to the internet or how your browser behaves.

Compromised files (missing, changed, encrypted, or duplicated)

A malware infection can damage files in quiet ways: documents won’t open, filenames change, or you see strange duplicates. Ransomware is the extreme case, but even adware can mess with browser data and cached files.

Unexpected page redirects

Redirects can come from ad-heavy sites, but repeated redirects on trusted websites can mean a hijacked browser setting, a rogue extension, or a malicious proxy.

If you detect several of the above signs on your Mac, it’s important to take action right away. This involves disconnecting from the internet, backing up important files, changing passwords, and running a good anti-malware program. But if that seems too overwhelming, we’re always here to help. Our Mac experts can remotely diagnose and fix any issues you may be experiencing with your Mac. Contact us now to protect your systems and data.