Temporal Key Integrity Protocol

Abstract: In this paper, we describe two attacks on IEEE 802.11 based wireless LANs. The first attack is an improved key recovery attack on WEP, which reduces the average number of packets an attacker has to intercept to recover the secret key. The second attack is (according to our knowledge) the first practical attack on WPA secured wireless networks, besides launching a dictionary attack when a weak pre-shared key (PSK) is used. The attack works if the network is using TKIP to encrypt the traffic. An attacker, who has about 12-15 minutes access to the network is then able to decrypt an ARP request or response and send 7 packets with custom content to network.

Abstract: We show that low-layer attacks against Wi-Fi can be implemented using user-modifiable firmware. Hence cheap off-the-shelf Wi-Fi dongles can be used carry out advanced attacks. We demonstrate this by implementing five low-layer attacks using open source Atheros firmware. The first attack consists of unfair channel usage, giving the user a higher throughput while reducing that of others. The second attack defeats countermeasures designed to prevent unfair channel usage. The third attack performs continuous jamming, making the channel unusable for other devices. For the fourth attack we implemented a selective jammer, allowing one to jam specific frames already in the air. The fifth is a novel channel-based Man-in-the-Middle (MitM) attack, enabling reliable manipulation of encrypted traffic.These low-layer attacks facilitate novel attacks against higher-layer protocols. To demonstrate this we show how our MitM attack facilitates attacks against the Temporal Key Integrity Protocol (TKIP) when used as a group cipher. Since a substantial number of networks still use TKIP as their group cipher, this shows that weaknesses in TKIP have a higher impact than previously thought.

Abstract: A system and method are disclosed that overcome deficiencies of prior art IEEE 802.11 WEP key management schemes. Preferred embodiments of the present system and method update WEP keys and rotate transmission key indices in a synchronized manner and on a frequent basis making it impractical for a hacker to gather sufficient network traffic using any one WEP key to decrypt that key and without disrupting communications. Preferred embodiments of the present system and method do not require changes in access point or mobile unit hardware, radio drivers, or firmware and are therefore compatible with existing or legacy network infrastructure or components. The disclosed system and method may be used to facilitate secure communications between one or more access points and one or more mobile units and/or groups of two or more mobile units engaging in peer-to-peer associations.

Abstract: The IEEE 802.11 Wireless LAN standard has been designed with very limited key management capabilities, using up to 4 static, hong term, keys, shared by all the stations on the LAN. This design makes it quite difficult to fully revoke access from previously-authorized hosts. A host is fully revoked when it can no longer eavesdrop and decrypt traffic generated by other hosts on the wireless LAN.This paper proposes WEP*, a lightweight solution to the host-revocation problem. The key management in WEP* is in the style of pay-TV systems: The Access Point periodically generates new keys, and these keys are transferred to the hosts at authentication time. The fact that the keys are only valid for one re-key period makes host revocation possible, and scalable: A revoked host will simply not receive the new keys.Clearly, WEP* is not an ideal solution, and does not address all the security problems that IEEE 802.11 suffers from. However, what makes WEP* worthwhile is that it is 100% compatible with the existing standard. And, unlike other solutions, WEP* does not rely on external authentication servers. Therefore, WEP* is suitable for use even in the most basic IEEE 802.11 LAN configurations, such as those deployed in small or home offices. A WEP* prototype has been partially implemented using free, open-source tools.