Public Wifi Security and Why it's a Problem? | LMG Security

Things not to do at a coffee shop: leave a computer unattended | Wikimedia Commons

For many people, it’s a relief to walk into a coffee shop and see a “Free Wifi!” sign. Without the proper precautions, however, these public Wifi points make their users easy targets for cyberattacks. Attackers have a number of strategies – many of which require little skill – to exploit unprotected wireless access points (WAPs) and put your public wifi security at risk. For those who find themselves working over open Wifi networks at coffee shops, hotels, and other public spaces, it’s critical to be aware of these attacks and understand what they can do to defend their data.

Here are three attacks to be aware of, along with defense strategies to counter them:

1. 1. Traffic sniffing – “Sniffing” refers to an attacker spying on a victim’s network activity by getting in the middle of the connection between the victim’s computer and the host(s) with which it is communicating. While Wifi networks protected by a security protocol like WPA2 encrypt traffic in transmission, attackers can use a number of free tools to decrypt the traffic. Then the attacker can see any login credentials users type in, any messages they send, which websites they visit, and more. Defending against traffic sniffing – The best defense against the inherent risk of public Wifi is the use of a virtual private network (VPN). The user logs in with a passphrase, and then the VPN sets up an encrypted tunnel for secure data transmission between two hosts. A VPN adds a critical extra layer of security. Those who don’t have access to a VPN should only make limited use of public Wifi and avoid using applications that require them to enter login credentials.
   2. Session hijacking – This attack is sniffing taken to the next level: attackers sniff a victim’s traffic to intercept an HTTP cookie (the little piece of data sent by websites to users’ computers so that websites can recognize them and maintain their online sessions). Attackers then use that stolen cookie to gain access to the victim’s online session. Defending against session hijacking – The SSL/TLS security protocol offers protection against this attack. So when using public Wifi, browser warnings along the lines of “The site you’re trying to visit is unsafe” or, more specifically, “SSL certificate for this site not trusted” should be taken seriously, as they could be evidence of session hijacking. Listen to these warnings and hit the back button.
   3. “Evil twin” attack – Another common attack strategy is setting up a WAP in the same physical location as a public network with an identical or very similar name: an “evil twin.” The attacker’s goal is to trick users into selecting their hotspot because they believe it is the legitimate one provided by the business. Once a user is connected to the “evil twin,” the attacker can see all of his/her network traffic, just as in a traffic sniffing situation.  Defending against the “evil twin” attack – Before logging on to the public network, verify that its name matches the name of the legitimate network exactly. As the two above descriptions indicate, however, simply being on the business’s legitimate network by no means guarantees security.

Employing a VPN is a smart way to enjoy the convenience of public Wifi networks while mitigating the risk. It is important to follow company policies and recommendations regarding the use of VPNs and of public Wifi in general. As long as it as authorized by their companies, users can make reasonably secure use of public Wifi by taking proper precautions.