The weakness of integrity protection for LTE

Abstract

In this paper, we concentrate on the security issues of the integrity protection of LTE and present two different forgery attacks. For the first attack, referred to as a linear forgery attack, EIA1 and EIA3, two integrity protection algorithms of LTE, are insecure if the initial value (IV) can be repeated twice during the life cycle of an integrity key (IK). Because of the linearity of EIA1 and EIA3, given two valid Message Authentication Codes (MACs) our algorithm can forge up to 2 32 valid MACs. Thus, the probability of finding a valid MAC is dramatically increased. Although the combination of IV and IK never repeats in the ordinary case, in our well-designed scenario, the attacker can make the same combination occur twice. The duplication provides the opportunity to conduct our linear forgery attack, which may harm the security of communication. To test our linear forgery attack algorithm, we generate two counter check messages and successfully forge the third one. We also examine the attack timing by simulating real communication. From the experimental results, our attack is applicable. The second attack is referred to as a trace extension forgery attack, which works only in theory. However, this attack is more general than the linear forgery attack. Known only one MAC and message pair, we can construct a different message, who has the same MAC as the original one, with the probability 1 2 16 . In this attack, trace function is applied to the message to shrink the guessing space.

Two new message authentication codes based on APN functions and stream ciphers

“…Because two constructions are AXU MACs, they are resistant against most attacks, except cycling attack and linear forgery attack . We only consider these two attacks in the remaining part of this section.…”

“…The experiment shows our constructions have overwhelming advantage in both efficiency and security compared with EIA1. One, the same platform, both of our new MACs are much faster than EIA1, and our constructions are resistant to the cycling attack and the linear forgery attack ; two, attacks that EIA1 suffers.…”

On simulation studies of cyber attacks against LTE networks

“…For these services, lack of availability would be disastrous. While attacks against confidentiality & integrity are feasible and have been studied [7], [8], prior research has extensively examined ways to launch DoS attacks [5], [9], [10] against the network. Popular variants are partial/full flooding and jamming [5].…”

“…A malicious adversary could also actively track subscribers by observing the temporary identities consecutively assigned to UE devices. According to [8], authentication in LTE is not mutual. In other words, an eNodeB will authenticate a UE device, but not vice versa.…”

“…One of the most common integrity attacks, usually applied during AKA, is the man-in-the-middle attack whereby a malicious adversary is allowed to change the contents of a message in transit. Prior work has concentrated on launching integrity attacks against UE devices or the Uu air interface that links UE devices and eNodeBs, especially the authentication process [17], [8].…”