I am researching about the weaknesses of WPA with TKIP. I have an idea that the AES-CCMP mode is better than TKIP, but what are the weakest points of TKIP? Also, I am wondering about the disadvantages of WPA TKIP. What are the disadvantages over WPA-AES?
Here's a relevant excerpt from a blogpost I did on here a few months ago:
WPA generally uses Temporal Key Integrity Protocol (TKIP). TKIP was designed by the IEEE 802.11i task group and the Wi-Fi Alliance as a solution to replace WEP without requiring the replacement of legacy hardware. This was necessary because the breaking of WEP had left WiFi networks without viable link-layer security, and a solution was required for already deployed hardware. TKIP is not an encryption algorithm, but it's used to make sure that every data packet is sent with a unique encryption key.
An excerpt from the aircrack-ng paper, Practical attacks against WEP and WPA:
TKIP implements a more sophisticated key mixing function for mixing a session key with an initialization vector for each packet. This prevents all currently known related key attacks because every byte of the per packet key depends on every byte of the session key and the initialization vector. Additionally, a 64 bit Message Integrity Check (MIC) named MICHAEL is included in every packet to prevent attacks on the weak CRC32 integrity protection mechanism known from WEP. To prevent simple replay attacks, a sequence counter (TSC) is used which allows packets only to arrive in order at the receiver.
There are two attacks known against TKIP:
- Beck-Tews attack
- Ohigashi-Morii attack (which is an improvement on the Beck-Tews attack)
Both of these attacks only could decrypt small portions of data, compromising confidentiality. What they can't give you is access to the network. To give you an idea of how much data can be recovered, a single ARP frame would take around 14-17 minutes to get the plain text. Getting useful information with this type of attack is very improbable (but not impossible) considering the rate of recovery.
More recent attacks:
Background: WPA-TKIP uses WEP's key structure, changing the 104-bit key on every packet using key mixing. The 24-bit IV is however generated from the low 16-bit of a replay counter, which still created keystream biases in RC4. They are however much more difficult to exploit than WEP's keystream biases where the 104-bit key is always the same.
You can gain complete access to a WPA(2) + TKIP network, if there is a client connected. It is trivial to deauth a client and capture the key exchange. This functionality is built into aircrack-ng once you have the 4 way handshake you can simply run it against a dictionary file until you find the key.
Here is a link that walks you through the process: https://web.archive.org/web/20160501103330/https://itfellover.com/9-wpa2-tkip-security-mode-cracking/