Skip to main content

Wi-Fi Security: Cracking WPA With CPUs, GPUs, And The Cloud

CPU-Based Cracking: Like Watching Paint Dry

Wireless Security Auditor: i5-2500k

If the guy trying to get into your network is only armed with a conventional desktop processor, don't fret about the security of your WPA-protected network. Those 16 388 SHA1 transformation invocations really bog down brute-force attacks. While we were able to crack WinZip archives at 20 million passwords per second in our previous piece, we're only able to manage about 5000 against WPA using an Intel Core i5-2500K.

Total Search Time Search, Assuming 5000 WPA Passwords/SecondPasswords Between 1 and 4 CharactersPasswords Between 1 and 6 CharactersPasswords Between 1 and 8 CharactersPasswords Between 1 and 12 Characters
NumbersInstant4 minutes6.5 hours7.5 years
Lower-case2 minutes18 hours1.5 years662 263 years
Alphanumeric (including Upper-case)52 minutes140 days1481 yearsNext Big Bang
All (Printable) ASCII characters5 hours5 years48 644.66 yearsNext Big Bang

How's this for a sense of futility? There's really no way to brute-force an alphanumeric password longer than six characters using our Core i5 processor. If you're using the entire (printable) ASCII set, a WPA password longer than five characters is reasonably safe.

CoWPAtty: i5-2500k

The calculations above assume you're running WSA in Windows, because the Linux route yields slightly worse CPU performance. Using CoWPAtty and Pyrit, we're down to 3307 passwords per second.

3949.1 PMKs: Pyrit Benchmark on i5-2500k

In the pages to come, we're going to present two numbers from Linux: the result from Pyrit's benchmark command and the figure reported by CoWPAtty using the Pyrit pass-through function. The Pyrit benchmark command is commonly used to highlight GPU performance, but it doesn't figure in the last couple of transformations needed to go from PMK to PTK. There is some overhead there because the PMK-PTK conversion occurs outside of Pyrit.

CoWPAtty and Elcomsoft's Wireless Security Auditor test the speed at which master keys are checked against the PTK information contained within captured packets. As such, those are the real-world numbers you would see in mounting a brute-force attack against a WPA-protected network.

  • fstrthnu
    Well it's good to see that WPA(2) is still going to hold out as a reliable security measure for years to come.
    Reply
  • runswindows95
    The 12 pack of Newcastles works for me! Give that to me, and I will set you up on my wifi! Free beer for free wifi!
    Reply
  • Soma42
    I think I'm going to go change my password right now...
    Reply
  • Pyree
    runswindows95The 12 pack of Newcastles works for me! Give that to me, and I will set you up on my wifi! Free beer for free wifi!
    Then either beer at your place is really expensive or internet is really cheap. Need 6x12 pack for me.
    Reply
  • compton
    Thanks for another article that obviously took a lot of work to put together. The last couple of articles on WiFi and archive cracking were all excellent reads, and this is a welcome addition.
    Reply
  • mikaelgrev
    "Why? Because an entire word is functionally the same as a single letter, like "a." So searching for "thematrix" is treated the same as "12" in a brute-force attack."

    This is an extremely wrong conclusion. Extremely wrong.
    Reply
  • What about the permutations of the words?
    i.e ape can be written:
    ape, Ape, aPe, apE, APe, aPE, ApE, APE.
    Thats 2^3=8 permutations. Add a number after and you get (2^3)*(10^1)=80 permutations.
    You can write PasswordPassword in 2^16=65536 ways.
    How about using a long sentence as a password?
    i.e MyCatIsSuperCuteAndCuddly, thats 2^25 permutations :)
    Reply
  • molo9000
    Any word on MAC address filtering?
    Can you scan for the MAC addresses? It's probably easy to get and fake MAC adresses, or it would have been mentioned.


    *scans networks*
    12 networks here,
    1 still using WEP
    10 allowing WPA with TKIP
    only 1 using WPA2 with AES only (my network)
    Reply
  • agnickolov
    Considering my WPA password is over 20 characters long I should be safe for the foreseeable future...
    Reply
  • aaron88_7
    "12345,&rel=ugc]http://www.youtube.com/watch?v=a6iW-8xPw3k]"12345, that's amazing, I've got the same combination on my luggage!"Still makes me laugh every time!
    Reply