If anyone asks how I can better secure my Wi-Fi, the relevant ones will propose encryption WPA2-PSK. It's the only really effective way to restrict access to your home Wi-Fi. But WPA2 encryption can be broken.
This publication is not a guide to breaking the encryption WPA2-PSK someone. It's an explanation of how your encryption could break and what you can do to protect yourself better.
There are two types of ways we can break a password, offline and online. In an offline attack, an attacker has a file with data that may attempt to break. For example, if an attacker manages to access and download a database with encrypted passwords, he could have as long as he wants to break them. It can use the appropriate tools to guess millions of times per second, depending on how fast the computer uses it.
An online attack is much more difficult and lasts a lot longer. For example, imagine an attacker trying to access your Gmail. He could guess some passwords, and then Gmail would block him, blocking access because he would recognize someone trying to guess the password.
We usually think that Wi-Fi is only vulnerable to online online attacks. Unfortunately, this is not true.
When a device connects to a Wi-Fi network with WPA-PSK encryption, it does something known as a “four-way handshake.” Essentially, this is the negotiation where the Wi-Fi base station and a device that requests connection, exchange password and encrypted information. This handshake is the Achilles heel of WPA2-PSK.
An attacker can use a tool like airodump-ng to monitor airborne traffic and capture the four-way handshake. Then he will have the untreated data he needs to perform an offline attack. With his quietness he can guess millions of passwords until he finds the one that suits the four-way handshake.
If an intruder can wait long enough to be able to "catch" the four-way handshake when a device is connected. However, it can carry out a "deauth" attack, which will forcefully disconnect your device from the Wi-Fi network you are using. It is known that your device will try to reconnect automatically, and this is exactly what the hacker wants, to catch the four-way handshake of the connection.
Breaking the four-way handshake
Once the data is obtained, the attacker can use a tool such as cowpatty or Aircrack-ng, μαζί με ένα “λεξικό” που περιέχει μια μεγάλη λίστα με πιθανούς κωδικούς πρόσβασης. Αυτά τα αρχεία χρησιμοποιούνται γενικά για να επιταχύνουν τη διαδικασία σπασίματος. Θα δοκιμάσουν κάθε συνθηματική φράση εναντίον των δεδομένων του WPA four-way handshake μέχρι να βρουν αυτή που ταιριάζει. Δεδομένου ότι πρόκειται για μια offline επίθεση, ο hacker έχει όσο χρόνο χρειάζεται και φυσικά η διαδικασία μπορεί να προχωρήσει πολύ πιο γρήγορα. Ο εισβολέας δεν θα πρέπει να είναι στην ίδια φυσική περιοχή, όπως το ίδιο δίκτυο, ενώ προσπαθεί να σπάσει την συνθηματική φράση. Ο εισβολέας θα μπορούσε δυνητικά να χρησιμοποιήσει το Amazon S3 ή άλλη υπηρεσία υπολογιστικού cloud ή κάποιου data center, dramatically speeding up the process.
All of the above tools are available on Kali Linux (formerly BackTrack), a Linux distribution designed for penetration testing.
There is no telling how long it would take an attacker to crack the password this way. If it's a long code, it could take years, maybe even hundreds of years or more. If the password is “password”, the process will probably take less than a second. As computers improve, this process speeds up. It's clearly a very good idea to use long passwords, 20 characters take a lot longer than 8 to crack. THE change of your password every six months or every year could also help.
There is also an attack on WPS, an incredibly vulnerable system carried by many routers enabled by default. On some routers, disabling the WPS environment does nothing - it stays on and waits for attackers to take advantage of it!
In fact, WPS forces the devices to use a 8-numbered PIN that bypasses the passphrase. This PIN is always checked in groups of the two 4-Voice Codes, and the connection device informs whether the four-digit segment is correct. In other words, an attacker has only to guess the first four digits and then he can guess the second four digits separately. This is a pretty quick attack that can be carried out by air.
WPA2-PSK is likely to have other vulnerabilities that have not yet been discovered. But we continue to say that WPA2 is the best way to secure your network because it is still.
