Detecting intrusions of your network can sometimes be difficult. You can’t assume it’s a big, catastrophic event.

In fact, hackers would prefer that you never notice at all. Here are five signs to be on the lookout for.

Your Firewalls or Anti-virus Software Are Disabled

If you find that they’re been turned off, it may be the first sign that a hacker is at work. With these disabled, a hacker can freely probe your system for weaknesses. The first time it happens you may assume it’s an application glitch. But you should disconnect from the internet and run a Security scan to be safe.

Passwords Have Changed

If you find that any passwords to your online accounts no longer work, you may have been hacked. They can be stolen by phishing emails, key-trapping spyware, or even guessed based on your social media posts. Once they have access, hackers can lock you out, steal funds, or damage your reputation. Use strong passwords on all sites and change them regularly. Never use the same password for multiple accounts.

Family or Associates Report Odd Emails from You

Cyber criminals gaining control of your email accounts can use them to defraud, harass, spread malware, or send spam to hundreds of people in your name. This can not only be embarrassing, but your email account could get black-listed as a spamming account by internet servers. Run a security scan of your computer, report the problem to your email provider, change the account password, and be prepared to make some apologies.

You Find Software You Didn’t Install

This is a clear sign your computer has been compromised. You can be infested with malware without realizing it if it’s hidden in other files or activated by clicking on a link. It could be harmless adware or it could be something very serious. Be cautious about downloading anything. As soon as you discover these phantom applications, try to uninstall them and run a scan to be sure it worked. If it didn’t, try doing a search on the application or .exe filename to find advise on how to remove it.

Internet Searches Get Redirected

Redirects are a common form of malware where you’re redirected to a certain page not matter what you’re trying to reach. It can also happen only when you try to reach a certain website. Often it’s malware trying to force you to buy something, and the hacker is getting paid for this. This often happens if you’ve downloaded a new toolbar. If you have this problem, uninstall any toolbars you don’t want and run a scan.

Internet providers have measures in place to protect users, but that doesn’t guarantee you’re safe. If you experience one of these signs and can’t find a solution, call a security expert.