Understanding Wireless Network Security and Learning to Hack WiFi [How to]

Wireless Security Protocols: WEP, WPA, and WPA2

Various wireless security protocols were developed to protect home wireless networks. These wireless security protocols include WEP, WPA, and WPA2, each with their own strengths — and weaknesses. In addition to preventing uninvited guests from connecting to your wireless network, wireless security protocols encrypt your private data as it is being transmitted over the airwaves. Wireless networks are inherently insecure. In the early days of wireless networking, manufacturers tried to make it as easy as possible for end users.

 Wireless Network Security and Learning to Hack WiFi

Wireless Network Security and Learning to Hack WiFi

The out-of-the-box configuration for most wireless networking equipment provided easy (but insecure) access to a wireless network. Although many of these issues have since been addressed, wireless networks are generally not as secure as wired networks. Wired networks, at their most basic level, send data between two points, A and B, which are connected by a network cable. Wireless networks, on the other hand, broadcast data in every direction to every device that happens to be listening, within a limited range.

Following are descriptions of the WEP, WPA, and WPA2 wireless security protocols:

Wired Equivalent Privacy (WEP): The original encryption protocol developed for wireless networks. As its name implies, WEP was designed to provide the same level of security as wired networks. However, WEP has many well-known security flaws, is difficult to configure, and is easily broken.

Wi-Fi Protected Access (WPA): Introduced as an interim security enhancement over WEP while the 802.11i wireless security standard was being developed. Most current WPA implementations use a preshared key (PSK), commonly referred to as WPA Personal, and the Temporal Key Integrity Protocol (TKIP, pronounced tee-kip) for encryption. WPA Enterprise uses an authentication server to generate keys or certificates.

Wi-Fi Protected Access version 2 (WPA2): Based on the 802.11i wireless security standard, which was finalized in 2004. The most significant enhancement to WPA2 over WPA is the use of the Advanced Encryption Standard (AES) for encryption. The security provided by AES is sufficient (and approved) for use by the U.S. government to encrypt information classified as top secret — it’s probably good enough to protect your secrets as well.

How does Hacking Tools Work

Many of  you know How to use Aircrack-ng, Airodump-ng, Airmon-ng. This Tutorials describes how these tool actually works, this could be important guide on ARP and Some Network Topics. Wireless networks are everywhere; they are widely available, cheap, and easy to setup. To avoid the hassle of setting up a wired network in my own home, I chose to go wireless. After a day of enjoying this wireless freedom, I began thinking about security.

How secure is my wireless network? I searched the Internet for many days, reading articles, gathering information, and participating on message boards and forums. I soon came to the realization that the best way for me to understand the security of my wireless network would be to test it myself. Many sources said it was easy, few said it was hard.

How a wireless network works

A wireless local area network (WLAN) is the linking of 2 or more computers with Network Interface Cards (NICs) through a technology based on radio waves. All devices that can connect to a wireless network are known as stations. Stations can be access points (APs), or clients. Access points are base stations for the wireless network. They receive and transmit information for the clients to communicate with. The set of all stations that communicate with each other is referred to as the Basic Service Set (BSS).

Every BSS has an Identification known as a BSSID, also known as the MAC address, which is a unique identifier that is associated with every NIC. For any client to join a WLAN, it should know the SSID of the WLAN; therefore, the access points typically broadcast their SSID to let the clients know that an AP is in range. Data streams, known as packets, are sent between the Access Point, and it’s clients. You need no physical access to the network or its wires to pick up these packets, just the right tools. It is with the transmission of these packets that pose the largest security threat to any wireless network.

Wireless Encryption Standards

If you’re confused about the different wireless encryption standards, then make use of the following examples are your basic wi-fi standard manual. Take note that all WEP and WPA with TKIP standards have long been considered insecure and, as such, aren’t recommended for use at all!
Wireless Protocols and Encryption Methods

Wireless Protocols and Encryption Methods

  • WEP (Wired Equivalent Privacy): The old, original, and currently discredited wireless security standard. Easily cracked.
  • WEP 40/128-bit key, WEP 128-bit Passphrase: See WEP. The user key for WEP is generally either 40- or 128-bit, and usually has to be supplied as a hexadecimal string.
  • WPA, WPA1: Wi-Fi Protected Access. The initial version of WPA, sometimes called WPA1, is essentially a brand name for TKIP. TKIP was chosen as an interim standard because it could be implemented on WEP hardware with just a firmware upgrade.
  • WPA2: The trade name for an implementation of the 802.11i standard, which includes AES and CCMP.
  • TKIP: Temporal Key Integrity Protocol. The replacement encryption system for WEP. Several features were added to make keys more secure than they were under WEP.
  • AES: Advanced Encryption Standard. This is now the preferred encryption method, replacing the old TKIP. AES is implemented in WPA2/802.11i.
  • Dynamic WEP (802.1x): When the WEP key/passphrase is entered by a key management service. Therefore, WEP didn’t support dynamic keys until the advent of TKIP and CCMP.
  • EAP: Extensible Authentication Protocol. A standard authentication framework. EAP supplies common functions and a negotiation mechanism, but not a specific authentication method. Currently, there are about forty different methods implemented for EAP. See WPA Enterprise.
  • 802.1x, IEEE8021X: The IEEE family of standards for authentication on networks. In this context, the term is hopelessly ambiguous.
  • LEAP, 802.1x EAP (Cisco LEAP): The Lightweight Extensible Authentication Protocol is a proprietary method of wireless LAN authentication developed by Cisco Systems. Supports dynamic WEP, RADIUS, and frequent reauthentication.
  • WPA-PSK, WPA-Preshared Key: Use of a shared key, meaning one manually set and manually managed. Does not scale with a large network either for manageability or security, but needs no external key management system.
  • RADIUS: Remote Authentication Dial In User Service. A very old protocol for centralizing authentication and authorization management. The RADIUS server acts as a remote service for these functions.
  • WPA Enterprise, WPA2 Enterprise: A trade name for a set of EAP types. Products certified as WPA Enterprise or WPA2 Enterprise will interoperate (EAP-TLS, EAP-TTLS/MSCHAPv2, PEAPv0/EAP-MSCHAPv2, PEAPv1/EAP-GTC & EAP-SIM).
  • WPA-Personal, WPA2-Personal: See Pre-Shared Key.
  • WPA2-Mixed: Support for both WPA1 and WPA2 on the same access point.
  • 802.11i: An IEEE standard that specifies security mechanisms for 802.11 networks. 802.11i uses AES, and includes improvements in key management, user authentication through 802.1X, and data integrity of headers.
  • CCMP: Counter Mode with Cipher Block Chaining Message Authentication Code Protocol. An encryption protocol that uses AES.

Packets and IVs 

It’s all in the packets. The bottom line is – while you may be able to employ several security features on your WLAN – anything you broadcast over the air can be intercepted, and could be used to compromise the security on your network. If that frightens you, start stringing wires throughout your home.

Every encrypted packet contains a 24 or 48 bit IV, depending on the type of encryption used. Since the pre-shared key is static and could be easily obtained, the purpose of the IV is to encrypt each packet with a different key. For example, to avoid a duplicate encryption key in every packet sent, the IV is constantly changing. The IV must be known to the client that received the encrypted packet in order to decrypt it; therefore, it is sent in plaintext.

The problem with this method is that the Initialization Vectors are not always the same. In theory, if every IV was different, it would be nearly impossible to obtain the network key; this is not the case. WEP comes with a 24 bit IV; therefore, giving the encryption 16 million unique values that can be used. This may sound like a large number, but when it comes to busy network traffic, it’s not. Every IV is not different; and this is where the issues arise. Network hackers know that all the keys used to encrypt packets are related by a known IV (since the user entered WEP part of the key is rarely changed); therefore, the only change in the key is 24 bits.

Since the IV is randomly chosen, there is a 50% probability that the same IV will repeat after just 5,000 packets; this is known as a collision. If a hacker knows the content of one packet, he can use the collision to view the contents of the other packet. If enough packets are collected with IV matches, your network’s security can be compromised.

The crack

Two of the most popular programs used for actually cracking the WEP key are Airsnort and Aircrack. Airsnort can be used with the .dump files that Kismet provides; and Aircrack can be used with the .cap files that Airodump provides. Airsnort can be used on it’s own without any other software capturing packets; although, it has been reported to be extremely unstable in this state, and you should probably not chance loosing all your captured data.

See also : Installing BackTrack OS on Vmware WorkStation

A better method would be to let Airsnort recover the encryption key from your Kismet .dump file. Kismet and Airsnort can run simultaneously. For this demonstration, we’ll be using Aircrack. You can use Airodump to capture the packets, and Aircrack to crack the encryption key at the same time.

Understanding Wireless Network Security and Learning to Hack WiFi [How to] With Airodump running, open a new command window and type:

aircrack -f 3 -n 64 -q 3 george.cap

The -f switch followed by a number is the fudge factor; which is a variable that the program uses to define how thoroughly it scans the .cap file. A larger number will give you a better chance of finding the key, but will usually take longer. The default is 2. The -n switch followed by 64 represents that you are trying to crack a WEP 64 key.

I knew because it was a setup; In the real world there is no way to determine what WEP key length a target access point is using. You may have to try both 64 and 128. The -q 3 switch was used to display the progress of the software. It can be left out altogether to provide a faster crack; although, if you’ve obtained enough unique IVs, you should not be waiting more than a couple minutes.

A -m switch can be used, followed by a MAC address, to filter a specific AP’s usable packets; this would come in handy if you were collecting packets from multiple APs in Airodump. Aircrack recovered my WEP 64 key within 1 minute using 76,000 unique IVs; the whole process took around 34 minutes. The same experiment was repeated with WEP 128 and it took about 43 minutes. The reason it was not substantially longer is because I simply let Airplay replay more packets. Sometimes you can get lucky and capture an ARP Request packet within a few minutes; otherwise, it could take a couple hours.


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