Dangerous Wi-Fi: how to protect yourself from hacking a wireless network with a KRACK exploit?

A security gap has been discovered in the updated WPA2 encryption standard. How hackers can act, who is vulnerable to KRACK exploit attacks in general and what should you do to protect your data?

For several years now, security experts and specialized magazines have been strongly recommending using WPA2 encryption when using Wi-Fi. And now it is in this standard that a security vulnerability has been discovered.

This has caused concern for many people, especially after that, how information security experts warned against using Wi-Fi and recommended using, for example, for online banking systems, only a cable connection.

But what really is the security gap discovered by the KRACK program? Who exactly is vulnerable? And what measures should users take? To begin with, we hasten to reassure you: for the user personally, the risk of attacks through KRACK is extremely low. The danger arises only in special cases, if it concerns a certain company or a certain person, which are purposefully monitored.

The first reason to hang up the alarm is that, that an attack on a Wi-Fi network is only possible at close range. The hacker must be within reach of your wireless network, to be able to carry out an attack at all. KRACK cannot be used from afar, and it can’t spread from one device to another, like a classic worm or virus.

Imaginary reliability of WPA2:

How does KRACK function?

The second reason to calm down is the structure and functioning of the KRACK exploit, opened by scientists of the Catholic University of Leuven in Belgium. This abbreviation stands for ‘Key Reinstalling Attack’ (an attack by reinstalling the key). To put it more simply, an attack using KRACK forces network participants to reinstall encryption keys, which protect WPA2 traffic.

WPA2 uses a one-time code sent over the radio to encrypt data transmission, which both connecting devices should know. During an attack on a Wi-Fi network, hackers catch only one part of the code and try to achieve that, so that the router will send it a second time soon.

But with a one-time code, this is impossible - as a result, hackers compare parts of the decrypted code with each other and thus calculate the code used step by step. Eventually they can read the transmitted data. Almost all devices are exposed to this danger, following the official WPA2 specification. First of all, these are smartphones and tablets based on Android, as well as computers with the Linux operating system.

Microsoft and Apple computers, and also iOS devices are only partially vulnerable, since both manufacturers did not follow the specification from the very beginning. They reacted very quickly and posted additional security patches for vulnerable systems online. Such Linux distributors, like Ubuntu, Fedora and openSUSE, we also concluded deals on the acquisition of these programs quite quickly. The Linux system was particularly vulnerable, since a null parameter was used during the updated code transfer.

By the green castle, as well as the prefix ‘https’ before the web address, you will understand, that the connection is encrypted.

Security by using SSL/TLS

There is also a third reason for peace of mind: already many Internet connections are encoded using SSL or TLS protocols. Even if the hacker manages to catch on to the connection, encrypted with WPA2, and read the data, he will see only encrypted information.

So, all connections to online banks, most online stores and many websites with usernames are already encoded. You will recognize the encrypted connection in the browser by the prefix ‘https’ before the address of the visited website.

Besides, Firefox search engines, Chrome and Edge show a green padlock in front of the web address. If you click on one of these locks, then you will learn further information about the current encryption systems and the certificates used for this. The certificate confirms, that the visited page belongs to the company, whose address you see in the browser.

Connections without SSL/TLS are not encrypted, and the information can be read relatively easily. If you want to prevent this, you can use a VPN (virtual private network). At the same time , all the data, incoming to or sent from your PC, they will go through a coded tunnel to the VPN provider. And only then will they get into the open Internet.

Thanks to the detailed description of the SSL certificate, you will definitely know, for whom and by whom it was issued.

For everyday use (for example, for reading the news) there is no need for such a procedure. Even many chat programs also use encoded connections. These include the popular Telegram and WhatsApp. Here hackers have no chance to get into the chat through hacking WPA2 and spy on your communication.

Taking countermeasures

However, all users should update the firmware on all devices in the house, using a Wi-Fi network. If possible, this will close all vulnerabilities for the penetration of the KRACK exploit. For old equipment, many manufacturers no longer release updates. But at least the most important suppliers of such routers, like TP-LINK, D-Link and Zyxel, they have already announced the presence of patches or even posted them online.

Returning to the previously used WEP or WPA encryption options is not a good idea. In particular, WEP was hacked several years ago. Here, decryption of the transmitted data is possible in relatively easy ways. In the case of WPA, with the help of KRACK attacks, it is even possible to partially change the transmitted data and cause direct harm in this way.

Vulnerable devices for KRACK

Computer Emergency Response Team (CERT) compiles a constantly updated list of manufacturers, vulnerable to KRACK, and their Wi-Fi devices. You will find the list at http://bit.ly/2hcO1y8

Click on ‘View More’, to see the entire list. Find the supplier you are interested in there (for example, using the keyboard shortcut ‘Ctrl F’) and click on the content in the ‘Status’ column. This way you will find out information about the actions of the relevant manufacturer, aimed at eliminating the shortcomings of their products. Some of the data also contains links to further information, posted on manufacturers’ websites.