Even if you have unlimited internet from one of the top 10 best internet service providers, WiFi theft is a problem, because hackers can use your WiFi connection to hijack internet-enabled devices or steal your data. So read these 10 simple steps to learn how to tell if someone is using your WiFi, and what actions you can take to protect yourself.
1. Notice any Slowdowns in Internet Speed
According to a Georgia Institute of Technology paper entitled Why is my internet slow?, the top reasons for internet slowdowns are high bandwidth use due to video streaming and deliberate slowdowns by your internet service provider (ISP). The latter, called throttling, is normal, and generally happens predictably during peak usage times.
However, if you see random decreases in speeds and regular buffering issues that do not usually happen, someone could be stealing your WiFi. To make sure, keep going down the list and see if any of the other points apply to you.
2. Take Note of any Surprising Ads
A paper by Microsoft that studied over 1 million ads notes that most of them use a form of targeting. Ad companies log your browsing habits, location, demographic information, and more to create content tailored to you. You may have noticed that, for the most part, the ads you see relate to recent purchases you’ve made or content that you regularly browse. After a recent online purchase, you will probably see your browser flooded with ads for similar or even identical products.
If you suddenly start seeing ads for something specific that you never bought or showed any interest in, this could be a sign of someone stealing your WiFi. The ads you are getting are based on that person’s browsing habits.
3. Review Your Internet Bills
Even if you don’t have unlimited data, your internet bill will probably stay pretty constant month-to-month unless you’ve downloaded something big or spent an unusual amount of time browsing. After all, we are all creatures of habit, which extends to our browsing. Activities like streaming take up a lot of bandwidth, so a telltale sign of a WiFi mooch is a higher-than-average internet bill. If it looks like a whole other person joined your internet bill this month, they probably did.
Review your history going back a few bills. If your bill jumped a while back and then stayed high, a thief may have joined your network and stayed on since that time.
If you have unlimited internet, you can still use your account statements to catch WiFi thieves. Your ISP should detail your bandwidth usage. Monitor bandwidth usage month by month and note any irregularities—they might be a sign that someone is mooching off your WiFi connection.
4. Check if Your Emails Are Going to Spam
Some thieves might be using your WiFi to do something that they would be uncomfortable doing from their home network. Spam emailing is a typical example. Spam emails work by sending a massive number of emails to a large list of recipients hoping that a few of them will reply.
Since spam is at best unwanted and at worst downright malicious, email providers take steps to limit its spread. One of the ways they do this is by tracking the email activities coming from a specific internet connection. Specifically, they look at your IP address, a unique identifier for your internet connection. If they see masses of spam emails coming from your IP address, they might block all emails from your IP.
If you notice your legitimate emails regularly going to other people’s spam folders, someone might have been using your WiFi to send spam emails. There might be a bit of a silver lining if this is the case, since the thief is probably long gone now that your IP has been blocked for spamming.
If this is a problem for you, change your WiFi password and contact your email provider’s customer service team to unblock your IP address.
5. Notice any Issues with Smart Home Devices
As smart home devices get increasingly popular, the danger WiFi thieves pose increases. A tech-savvy thief with access to your WiFi password could potentially take control of your smart home devices, gaining the ability to hear audio, see video, or otherwise surveil and interact with your home.
If you see your smart home devices behaving erratically—turning off and on regularly without prompting, for instance—your WiFi might be compromised. Change your WiFi password, power down any smart home technology immediately, and contact your smart home’s customer support team if you suspect that your smart devices have been compromised.
6. Check Your Bank Statements
One of the more nefarious reasons for stealing your WiFi is to gain access to your personal data. Criminals might then use this data to impersonate you and make purchases or access funds in your bank account using your name. This is identity theft, and it can have disastrous financial consequences.
Regularly monitor your monthly bank statements and immediately report any unusual or unauthorized transaction to your bank’s customer service team. If you suspect that you were the victim of identity theft, change your WiFi password.
However, note that there are many ways that identity theft can occur—WiFi theft is just one of them. To make sure that WiFi theft is the culprit, you will need to check your router. If you are concerned about identity theft, take a look at our list of the top 10 best identity theft protection services to help protect your personal data.
7. Check the Lights on Your Router
Every router is different, but most models have a set of indicator lights that display basic information. Common indicators include a light to show that the router is connected to power, another that shows it is connected to the internet, and another to show that your WiFi network is currently in use. It is this last light that concerns us.
If you suspect that a thief is currently using your WiFi, you can check by disconnecting all of your devices from the internet. If someone outside your home is connected to your WiFi, the light should still be on, even after you’ve disconnected everything.
This trick is harder to do if you have a lot of WiFi-enabled devices, such as smart home technology, since every single device has to be disconnected for this to work. Plus, you may want to check several times to make sure you catch the thief at a time they’re online.
8. Use an App
Various third-party applications exist to test for unknown WiFi connections. They all work the same way. Once you download the application, you will create a list of friendly devices to check against. Then, every time an unknown device connects, the app will notify you of an unknown WiFi connection.
While this app might not work against a seasoned hacker, it will certainly catch your average WiFi mooch. If you have not downloaded one already, consider picking up a WiFi theft detection app.
That said, these apps are not perfect. If you see any of the previous warning signs on this list, do not dismiss them simply because the app did not find anything.
9. Check Your Router’s Client List
Instead of using an app, you can manually check your router’s client list. The client list shows all the currently active WiFi connections for your router. While the process will differ slightly depending on your router model, you should be able to find the client list by logging in to your router.
When you log in, click on a tab called WiFi Client List, or simply Client List, and review the connected devices. Note that devices are listed according to their device name. You can usually find the name of any device you own in its settings menu. For a Windows computer, navigate to Settings > System. You will see your device name at the top of the screen.
If you see a device that does not correspond to something you own, someone is probably using your WiFi. If you are not sharing your network with a friend or relative voluntarily, it is likely an intruder. Turn your WiFi off and change the password. The unknown device should disappear from the list. Keep checking your client list regularly for a while to make sure it does not reappear.
10. Check Your Router’s Logs
Checking the client list only works if the WiFi thief is currently using your wireless network. Your router should have a timestamped log of past connections in the same menu where you found the client list. This log is the most reliable but the most time-consuming way of checking for WiFi thieves.
Your router’s logs will contain a timestamped history of every device that has connected to the internet in your home, when it connected, and when it disconnected. Depending on how many devices you have and your browsing habits, scrolling through multiple days of logs to find an unknown device could be very tedious.
That said, if you have a rough idea of when the thief might be operating, checking your router logs is the most reliable way to get hard evidence of past WiFi thievery.
WiFi theft is a serious issue that leaves your personal data and smart home devices vulnerable to attack. If you suspect that you are a victim of WiFi theft, change your password immediately. Afterward, go through the steps in this guide to make sure that nobody is using your wireless network without authorization.
If you like, you can go further to mitigate the threat by switching to a more secure internet service provider, such as Cox. Or, if you have a lot of smart home devices, you can stay on top of any suspicious smart home activity with an app, such as the one provided by AT&T.