Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Mobile Security //

Cellular Network

09:05 AM
Larry Loeb
Larry Loeb
Larry Loeb

Researchers Show How Attackers Can Crack LTE Data Link Layer

In a paper, researchers show how an attacker with the right equipment can crack the data link layer of an LTE network. It's mostly theoretical, but it shows why upcoming 5G security standards need to be tougher.

A new report by security researchers at Ruhr-University Bochum and New York University Abu Dhabi has shown how the data link layer of the 4G LTE mobile telephony standard can be defeated.

In their paper, entitled "Breaking LTE on Layer Two," the researchers show two passive attacks that can determine many details -- including identity and website fingerprinting -- about the traffic along with an active attack that can change where the traffic ends up.

The snappy name they gave to the active attack is aLTEr. It can carry out DNS spoofing to redirect traffic.

However, the attacks are not something most users will have to concern themselves with right now. While the paper showed the feasibility of the attacks, it required use of an experimental network set up by the researchers that may not translate well into normal use.

(Source: Flickr)
(Source: Flickr)

That setup had some limiting factors.

For instance, the researchers note:

We use a shielding box to prevent our relay from interfering with the commercial network in the licensed spectrum, following ethics guidelines. Further, the shielding box stabilizes the user equipment's (UE) radio connection and prevents non-deterministic behavior of the relay. In other words, the shielding box setup assures that the UE does not connect to any other available cell and the malicious relay does not interfere with itself.

Some might say that the researchers actually stacked the deck to make things work for them.

They also asserted that their results will be real-world possible, even though they did not directly do it: "While we use this to simplify the experimental procedure, the setup is comparable to IMSI catcher [so-called 'Stingray' boxes used by law enforcement -- ed.] attacks when considering the victim's perspective. Such attacks were conducted successfully in real-world environments, i.e., without shielding equipment."

The aLTEr attack "exploits the missing integrity protection of LTE user data to perform a chosen-ciphertext attack," according to the researchers. It depends on a malicious relay acting as a rogue base station towards the user. The implicit assumption here is that the UE will first connect with the rogue station.

See how that UE shielding used in their experimental setup all of a sudden becomes really significant?

Boost your understanding of new cybersecurity approaches at Light Reading's Automating Seamless Security event on October 17 in Chicago! Service providers and enterprise receive FREE passes. All others can save 20% off passes using the code LR20 today!

Second, the relay acts as an unauthenticated user in the commercial network, and must be undetected by that network. Researchers think that by forwarding all messages between the user device and the network, the malicious relay will be undetectable.

However, the underlying problem exploited by aLTEr is that 4G data packets are not integrity-protected by the counter mode (AES-CTR) that is used. Instead, an attacker can intercept packets, alter them, and then relay those modified packets. And here the researchers have made a good point: While the 5G standard does include some stronger encryption, operators may not use it because of the overhead that is necessary to do so and can slow the speed of a network.

The researchers state their goals simply: "We urgently demand the implementation of effective countermeasures in the upcoming 5G specification to assure the security and privacy of future mobile communication."

Related posts:

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.

Comment  | 
Print  | 
More Insights
Newest First  |  Oldest First  |  Threaded View
How SolarWinds Busted Up Our Assumptions About Code Signing
Dr. Jethro Beekman, Technical Director,  3/3/2021
'ObliqueRAT' Now Hides Behind Images on Compromised Websites
Jai Vijayan, Contributing Writer,  3/2/2021
Attackers Turn Struggling Software Projects Into Trojan Horses
Robert Lemos, Contributing Writer,  2/26/2021
Register for Dark Reading Newsletters
White Papers
Cartoon Contest
Current Issue
2021 Top Enterprise IT Trends
We've identified the key trends that are poised to impact the IT landscape in 2021. Find out why they're important and how they will affect you today!
Flash Poll
How Enterprises are Developing Secure Applications
How Enterprises are Developing Secure Applications
Recent breaches of third-party apps are driving many organizations to think harder about the security of their off-the-shelf software as they continue to move left in secure software development practices.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
PUBLISHED: 2021-03-05
The Blog module in Kentico CMS 5.5 R2 build 5.5.3996 allows SQL injection via the tagname parameter.
PUBLISHED: 2021-03-05
Deutsche Post Mailoptimizer 4.3 before 2020-11-09 allows Directory Traversal via a crafted ZIP archive to the Upload feature or the MO Connect component. This can lead to remote code execution.
PUBLISHED: 2021-03-05
ssh-agent in OpenSSH before 8.5 has a double free that may be relevant in a few less-common scenarios, such as unconstrained agent-socket access on a legacy operating system, or the forwarding of an agent to an attacker-controlled host.
PUBLISHED: 2021-03-05
The npm package ansi_up converts ANSI escape codes into HTML. In ansi_up v4, ANSI escape codes can be used to create HTML hyperlinks. Due to insufficient URL sanitization, this feature is affected by a cross-site scripting (XSS) vulnerability. This issue is fixed in v5.0.0.
PUBLISHED: 2021-03-05
A flaw was found in newlib in versions prior to 4.0.0. Improper overflow validation in the memory allocation functions mEMALIGn, pvALLOc, nano_memalign, nano_valloc, nano_pvalloc could case an integer overflow, leading to an allocation of a small buffer and then to a heap-based buffer overflow.