Most small business owners don’t find out they’ve been hacked until the damage is already done. By the time the ransomware note appears or the suspicious bank transfer goes through, attackers have often been inside the network for weeks — or months.
Here are 7 warning signs that your business may have already been compromised, and what to do about each one.
1. Your Computer Is Running Unusually Slow
If your machines have slowed down significantly without any obvious reason — new software, heavy updates — it could indicate background processes running malicious code, mining cryptocurrency, or exfiltrating your data.
What to do: Run a full malware scan using a reputable tool (Malwarebytes, CrowdStrike Falcon, or similar). Check Task Manager for unknown processes using high CPU or network activity.
2. Unexpected Password Reset Emails
If you or your employees are receiving password reset emails you didn’t request, this is a classic sign that someone is trying to gain access to your accounts — or already has.
What to do: Enable multi-factor authentication (MFA) on all accounts immediately. Change passwords for any account that received an unsolicited reset email.
3. Unknown User Accounts Have Appeared
Attackers frequently create backdoor accounts to maintain access even after their initial intrusion method is discovered and closed. Check your user directories — Active Directory, Google Workspace, or your CMS — for accounts you don’t recognize.
What to do: Audit all user accounts monthly. Remove any accounts that aren’t assigned to a real employee. Enable alerts for new account creation.
4. Your Customers Are Reporting Spam from Your Email
If clients are getting suspicious emails “from you” that you never sent, your email account or domain may be compromised. Attackers use business email compromise (BEC) to impersonate executives and trick employees or clients into wiring money or sharing credentials.
What to do: Check your email “Sent” folder for messages you didn’t write. Review your SPF, DKIM, and DMARC records. Change your email password and enable MFA.
5. Unusual Network Traffic at Odd Hours
If your router logs show large amounts of data being transferred at 3 AM when no one is in the office, that’s a major red flag. Attackers often exfiltrate data during off-hours to avoid detection.
What to do: Review your firewall logs and router activity. Set up alerts for unusual bandwidth usage. Consider a 24/7 monitoring solution.
6. Your Antivirus Has Been Disabled
One of the first things sophisticated attackers do when they gain access is disable your security tools. If your antivirus software shows as “disabled” or “out of date” without anyone on your team doing it, this is a critical warning sign.
What to do: Re-enable and update your security tools immediately. Investigate how the software was disabled. Consider upgrading to endpoint detection and response (EDR) software.
7. Ransom Notes or Strange Files Have Appeared
The most obvious sign: files encrypted with strange extensions (.locked, .encrypted, .WNCRY) or text files demanding payment. If you’ve reached this point, you’re dealing with an active ransomware infection.
What to do: Disconnect affected machines from the network immediately. Do NOT pay the ransom — it doesn’t guarantee recovery and funds criminal activity. Contact a cybersecurity incident response team immediately.
What To Do If You Think You’ve Been Hacked
The most important thing is to act fast. Every minute an attacker stays inside your network, more damage is done. Here’s the immediate response checklist:
- Disconnect affected systems from the internet
- Change all passwords — especially admin accounts
- Enable MFA on all critical accounts
- Contact your IT team or a cybersecurity firm
- Document everything (screenshots, logs, timeline)
- Notify your bank if financial data may be involved
At MVP Projects, we offer a Security Audit that identifies vulnerabilities before attackers can exploit them. If you suspect you’ve already been compromised, our incident response team can help you assess the damage and secure your systems.