6 Hidden Places Cybercriminals Install Malware (That Most Teams Never Check)

When people think of malware, they imagine something dramatic — flashing warnings, broken systems, or a computer that suddenly refuses to cooperate. But modern cybercriminals don’t want to be noticed. Their goal is to hide, stay quiet, and collect data while your team carries on like nothing’s wrong.

And unfortunately, most businesses only check the obvious places. Meanwhile, attackers slip into the corners of your network no one ever thinks to inspect.

Here are six hidden places where malware loves to hide — and where most teams never bother to look.

1. Browser Extensions You Don’t Remember Installing
Extensions look harmless, but a single shady plug-in can collect passwords, monitor browsing, or inject ads.

Red flags:

Extensions employees don’t remember installing

Tools that ask for “full access” to browser activity

Add-ons that mysteriously reappear after removal

If you don’t manage extensions company-wide, someone else might be managing them for you.

2. Startup Programs Running in the Background
Malware that launches at startup blends in with legitimate tools and hides inside Windows or macOS boot processes.

Why it’s dangerous:
It activates automatically every time the device turns on — giving attackers a free pass daily.

Check for:

Unknown apps launching on boot

Programs using too much CPU or memory

Tools without an identifiable source

3. Old, “Forgotten” User Accounts
Former employees. Old contractors. Temporary accounts that were never deleted.

Attackers love unused accounts because:

Nobody monitors them

Passwords never change

Access permissions remain wide open

A dormant account with access is almost as dangerous as a stolen password.

4. Outdated Software You Didn’t Know Was Still Installed
Even if your main apps are updated, old versions of programs often stick around quietly.

Hackers look for these because:

Old software has known vulnerabilities

Security patches don’t apply to unused versions

Most teams don’t scan for them

It’s like leaving a broken lock on a back door.

5. Network Devices No One Logs Into
Printers. Scanners. VoIP phones. Old routers.

If it’s on your network, it’s an entry point — and most businesses never update or monitor these devices.

Why attackers love them:

They run outdated firmware

They’re rarely password-protected

They provide quiet access into your main network

6. Cloud Folders With “Temporary” Permissions
Files shared “just for now” often stay accessible forever.

Attackers know cloud misconfigurations are one of the easiest ways in.

Common mistakes include:

Public links left open

Folders shared with “Anyone with the link”

Overly broad permissions for convenience

One wrong share setting can expose sensitive information without you realizing it.

Final Thought
Malware doesn’t hide in obvious places anymore. It hides where security teams aren’t looking. The solution isn’t paranoia — it’s consistency: regular scanning, device monitoring, and proactive IT support that checks the places most teams forget.

At ETTE, we help small businesses uncover these blind spots before attackers take advantage of them.

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