The dangers of public Wi-Fi
Written by Joseph Poppy on 21/06/2019
But what about encryption?
As mentioned before, a great deal of the data leaving your device will be encrypted, meaning those nefarious middlemen won’t be able to do much with what they get. However, not all encryption is created equal and not everything is encrypted. In recent years there has been much ado about HTTPS and how much better it is than HTTP, and that has pushed the majority of sites to use it. However, not every site does.
If you are like me, you have every single app running in the background on your phone (and constantly question why your battery drains so quickly), it’s likely that these are set up to check in with their servers every once in a while. If they’re doing that on public networks, then any data they send out can be gobbled up too. Again, this data is often encrypted, but every app is different with many not being built with security in mind. Just ask some of our penetration testers. Man-in-the-middle attacks are so easy to execute on public Wi-Fi that the risks outweigh the benefit.
Let’s not forget that there are various levels of encryption. Over the years we’ve seen new versions of TLS emerge, meaning there have been weaknesses in the cryptography used previously. There’s nothing to say that app developers have kept their security implementation up to date, nor that someone will find a way to crack whatever the latest encryption standard is in the future.
Another process hackers often employ is one I have used myself on occasion when the person in front of me on the bus is reading a good book. Shoulder surfing is indeed a danger when working on public Wi-Fi. All sorts of information can be gleaned from a casual or not-so-casual glance. These wandering eyes can soak up logins and other pieces of sensitive information and potentially log into your accounts. Or, they can see what sites you browse and log into, potentially your username (maybe even your email) and they have some information to do some brute forcing with or craft a more convincing phishing email.
Once you’ve inadvertently installed malware onto your machine, hackers can then compromise other networks you choose to connect to, and any machine connected to them. Next time you take that laptop into work, congratulations, you’ve just compromised your work network too.
Endpoint attacks are common in any network, but more so on a public one. An endpoint is any internet capable device on a network, be it a desktop, laptop, phone or tablet. Any one of these can provide entry to a network. In a business environment, most endpoints will have been built to a specification which hopefully adheres to security best practices. If they aren’t in your business, start doing that. Even so, not everyone diligently installs their updates. If you operate on a BYOD policy, you could be at a greater risk, not everyone’s computer will be as secure or as up to date. If you’re on a public Wi-Fi, you’re at the mercy of everyone’s lax security approach.
Compromising one endpoint can be done in a number of ways, for example, a hacker could set up a malicious website that users browse to, thus letting them in. If they’ve set up their own rogue access point (see below), then they can forcibly direct everyone to the malicious website at their leisure. If someone else sitting on the network gets hacked, then said hacker potentially has access to every device on it, including yours.
It’s worth noting that if your machine is compromised, any site that you have set to ‘remember your credentials’ may well be visible to the hacker. This could lead to them accessing personal information and even potential credit card info. It will also allow them to craft some fairly convincing phishing emails.
There go my lattes
So, should you avoid using public Wi-Fi? The convenience factor of public Wi-Fi is impossible to dismiss, but you definitely need to take precautions. Public Wi-Fi is susceptible to the same threats as any other network, only they’re much more vulnerable to them. Mostly, it comes down to not knowing who set them up or who’s connected to them. Infected devices and man in the middle attacks are more likely to cause havoc on public networks than private ones. Ensure your phone and laptop are kept updated and that your firewall is appropriately configured. Be careful what apps you're using and make sure the sites you visit are HTTPS.
It's at this point one might recommend using a secure VPN to add an extra layer of security to your communications, but even this is no sure thing if the public network itself is already compromised. Still, take every precaution you can. Public Wi-Fi is great and isn’t going anywhere. If you are going to use them, and you probably are, be on top of your cyber security.
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