It is often said that using public wifi is dangerous. There have been numerous warnings about using coffee shop WIFI, airport WIFI, or other freely available WIFIs. At the Olympics in Rio there were many reports of bogus WIFI networks popping up around the city.
The question is what can happen to you if you are on an untrusted WIFI network. One of the dangers is snooping, anyone on the network can see data that is passed unless the data is encrypted. This means any username, passwords, and other information that is passed across the network could be intercepted.
In fact, if someone running the network sets up bogus DNS servers you cannot trust that you will be sent to the site that you typed in the address of.
If you are going to a site that is secure usually this is reflected by a green lock in your browser.
This will protect you from most of the simpler attacks. People snooping on the network can see which sites you are going to, but not data you are sending back and forth.
It is much more difficult to fake these sites, since the site sends you a certificate to prove its authenticity.
You also want to choose the option on your operating system to let it know that you are on a public network. This will prevent the computer from showing any shared drives that are set up on the computer.
If the WIFI spot is set up by a hacker, it might not even be safe to go to secure sites. This can happen because web addresses can be made with letters from non-English letters that will look like English. So the user thinks that they are going to bankofamerica.com website but they are actually going to bankofamerica.com where the “O” is a Cyrillic О. This site could then capture your data and then send it to the real bankofamerica.com site. To the user it would appear that they were on the correct site and it would look as it normally looked.
To prevent against this type of attack it is recommended that you use a Virtual Private Network (VPN) on an untrusted network. A VPN is software that encrypts the traffic between your computer and another machine allowing you to appear as if you are the other machine.
This way you connect to a VPN server while passing certificates to verify each other’s identity.
The safest option when using public WIFI is a VPN, but if you trust that the network is not compromised you may be safe with simply browsing https.