Know How... 102

We talk about the new Raspberry Pi B+, expert guest Aaron Newcomb goes over the different flavors of linux, learn how a remote control car suspension works, and put your black hat on for ARP Cache Poisoning Attack.

News Topic

Raspberry Pi B+ Announced

Linux 101

Aaron Newcomb shows the different flavors of Linux.

Remote Control Car Suspension

Coil Overs and Ball Bearings explained

The ARP Cache Poisoning Attack

The ARP Cache Poisoning Attack

• ARP = "Address Resolution Protocol"
• MAC = "Media Access Control"

Most of us think that our computers are identified by their IP address.

• However, on an ethernet network, they're actually identified by their MAC address (Media Access Control)
• A MAC is a 6-byte Hexideximal string that looks like, "00:11:aa:bb:cc:dd"

When we connect a computer to a network, it needs to become aware of all the other devices on the network, and all the other devices on the network need to become aware of the device.

• That's what ARP does: It correlates an IP address to a MAC address so that we can find a computer on the network with a particular IP address

Here's how it works:

• Computer A needs to send a file to Computer B
• Computer A knows that Computer B has the IP address of 192.168.1.2
• Computer A does an ARP Broadcast saying, "Hey! Who has the IP address 192.168.1.2?"
• Computer B hears the broadcast and responds, "I Do! 00:00:00:aa:aa:aa"
• Computer A know knows how to send the file to Computer B

Here's how access to the Internet Works:

• Computer A connects to the Network and receives a DHCP address of 192.168.1.3 with a gateway of 192.168.1.1
• It wants to sent data through the gateway to the Internet, so it does an ARP Broadcast saying, "Hey! Which of you is the gateway at 192.168.1.1?"
• The router(gateway) responds, "I'm 192.168.1.1 aa:bb:cc:dd:ee:ff
• Computer A sends data through the gateway at aa:bb:cc:dd:ee:ff
• Important to note is that all the devices will CACHE that response: so they all know which IPs belong to which MAC addresses.

Here's how a CACHE Poisoning Attack Works:

• Computer A wants to send data to the Internet, so it does an ARP Broadcast saying, "Hey! Which of you is the gateway at 192.168.1.1?"
• The router responds, "I'm 192.168.1.1 aa:bb:cc:dd:ee:ff"
• The attacking computer takes note that the gateway is at aa:bb:cc:dd:ee
• The attacking computer responds CONTINUOUSLY "I'm 192.168.1.1 22:22:22:22:22:22"
• Computer A sends data through WHAT IT THINKS is the gateway at 22:22:22:22:22:22
• The attacking computer receives the data, sniffs it, then sends it on to the REAL gateway at aa:bb:cc:dd:ee:ff

Using Cain and Abel

1. Download and Install Cain and Abel
2. You may need to disable global taskoffloading (netsh int ip set global taskoffload=disable)
3. Run the Sniffer
4. Switch to the Sniffer tab and hit the "+" icon to add a range scan (Use the IP range you're a part of)
5. Switch to the "ARP" tab at the bottom of the screen
6. Hit the "+" icon to Select your router and the client that you want to poison (or multiple clients)
7. Hit the "ARP" icon in the top bar to start the attack
8. Run Wireshark for more clear information

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• Transcripts: Know How... 102 (Transcript)