5 Signs Your Business Has Already Been Compromised

Most cyberattacks aren't discovered the moment they happen — they're discovered weeks or months later, after real damage has been done. If you know what to look for, you can catch a problem early and limit the harm to your business.

Your Computers or Network Are Acting Strange

Slow machines, programs crashing for no clear reason, or your internet connection dragging even when nobody's doing anything heavy — these aren't always just IT annoyances. Attackers often run software in the background that quietly uses your computing power or sends data out through your network. If multiple staff members are suddenly complaining about performance at the same time, that's worth taking seriously, not just rebooting and moving on.

You're Seeing Logins From Places That Don't Make Sense

Most cloud business tools — Microsoft 365, QuickBooks Online, your banking portal — keep a log of where and when accounts are accessed. If you or your IT person checks those logs and sees sign-ins from cities you've never visited, unusual hours like 3 a.m., or multiple failed attempts followed by a successful one, someone may already have access to your accounts. This is one of the most common early warning signs, and it often goes unnoticed because nobody thinks to check.

Customers or Vendors Are Reporting Something Odd

Sometimes your own clients or suppliers are the ones who spot the problem first. They might tell you they received a strange email that looked like it came from you, got an unusual invoice request, or were asked to change payment details out of nowhere. This is a pattern called Business Email Compromise, and it's one of the costliest scams targeting Canadian small businesses right now. If someone reaches out saying something felt off about a message from your company, take it seriously immediately.

Files Have Changed or Gone Missing Without Explanation

Ransomware — the type of attack where criminals lock your files and demand payment — usually gives warning signs before it fully takes hold. Staff might notice files they can't open, folders with strange names appearing on shared drives, or documents that seem to have been moved or renamed. If anyone on your team flags something like this, shut the affected machine off the network right away and call for help. Acting fast can be the difference between recovering most of your data and losing it all.

Your Security Tools Have Gone Quiet — Or Been Turned Off

Antivirus software, firewall alerts, or monitoring dashboards that suddenly stop sending notifications aren't necessarily fixed — they may have been disabled. Attackers will often try to turn off your defences as a first step so they can move around your systems without triggering alarms. If your IT person or MSP notices that logging has stopped or a security tool is no longer reporting, treat it as a red flag until proven otherwise.

What This Means For Your Business

None of these signs on their own is definitive proof of a breach, but any one of them is reason enough to pause and investigate. The biggest mistake Canadian SMB owners make isn't ignoring security altogether — it's assuming that unusual activity has a boring explanation and moving on without checking.

If something feels off, the cost of a quick investigation is almost always far lower than the cost of finding out later that you were right to be concerned. If you're not sure what you're looking at, that's exactly what a managed security provider is there for.