Why Your 2G Cellphone Network Data Encryption was Intentionally Weakened

You might think that the data you receive via your cellphone network is safe and secure. You’d be wrong. 

Recent research reveals a flaw in the encryption algorithm used in older 2G cellular phones that may have allowed hackers to eavesdrop on your data traffic. Even worse, it appears that the flaw was intentional.

Understanding 2G Networks and Data Encryption

There have been several generations of technology involved in the transmission of cellphone signals. The first generation, dubbed 1G, was entirely analog and transmitted only voice data, not digital data, in the 800 MHz band. The second generation— dubbed 2G came into use in 1991 and enabled the transmission of both voice and digital data. That meant that mobile phones could now handle voice calls, text messages, and digital data for email and Internet access. It’s an old technology today but was state-of-the-art twenty years ago.

Unfortunately, cybersecurity was not as good back then as it is today. Over the years researchers have uncovered many vulnerabilities in 2G technology, all of which have been mitigated with newer 3G, 4G, and now 5G networks and phones.

The primary problem with 2G is that, even though it encrypts its data transmissions, it uses very weak and easily cracked encryption. That problem is compounded by the lack of authentication between cell towers and individual phones, which makes it easier for malicious actors to impersonate a real 2G cell tower and eavesdrop on data transmissions that way.

Even though 2G technology is known to be susceptible to eavesdropping and spoofing, it’s still supported by modern cellphones – even the latest 5G models. That’s because not every location around the world has built out newer 3G, 4G, and especially 5G towers. In some areas all you can get is 2G – and it’s still as vulnerable as it was two decades ago.

What Researchers Discovered

On top of the traditional vulnerabilities associated with 2G technology, researchers in Europe have discovered a flaw in the encryption algorithm used by some 2G cellphones. This flaw, present in the original 2G technology, could have enabled malicious actors to spy on data traffic for more than twenty years.

There are two different 2G standards used worldwide – CDMA and GSM. The mobile data technology used in the GSM standard is called GPRS (General Packet Radio Service), and it uses the GEA-1 encryption algorithm. It is this algorithm that contains the newly discovered flaw.

The flaw revolves around the fact that, although GEA-1 supposedly uses a 64-bit encryption key, the effective key length is just 40 bits. That means that GEA-1 only provides 40-bit security, which is what could allow a hacker to easily decrypt all 2G GSM communications. 

It gets worse. It appears that this vulnerability in the GEA-1 algorithm was not an accident. The researchers believe that the flaw was intentionally baked into the algorithm to provide a backdoor for law enforcement agencies to access sensitive data transmissions. It also enabled cellphone companies to comply with laws in some countries that restrict the export of strong encryption tools.

The European Telecommunications Standards Institute (ETSI) that designed the GEA-1 algorithm later admitted that the built-in vulnerability was intentional to comply with restrictions in countries that did not permit the export of stronger encryption. An ETSI spokesperson commented, “We followed regulations” at the time that limited encryption strength. 

Should You Be Concerned?

GEA-1 was only used on GSM 2G networks and only for a few years. The GEA-1 algorithm was superseded by GEA-2, GEA-3, and GEA-4 encryption, all of which are stronger and do not contain the same vulnerability. By the time GEA-2 was released, the export controls on encryption had been eased, enabling the use of stronger encryption across the board. 

Today, most cellular traffic is sent over 4G (LTE) networks, with newer 5G technology emerging in some areas. Both 4G and 5G networks, as well as the previous 3G networks, all use much stronger transport encryption so that older vulnerabilities no longer pose a major risk to data security.

The risk, however, is not zero. The vulnerable GEA-1 encryption still exists because 2G is still supported in some mobile phones and is still used as a fallback by some cellular providers in some countries. While reverting to 2G and its vulnerable GEA-1 encryption is unlikely in today’s world, it is still possible. 

In short, the newly discovered vulnerability is not something to worry about today, although the fact it did expose data in the past is concerning. It’s also concerning that the vulnerability was deliberate, which makes some security experts wonder if similar intentional flaws could be inserted into today’s newer cellular phones. The only surefire way to protect against such vulnerabilities, experts advise, is to use a messaging system that employs true end-to-end encryption, such as that offered by companies such as Wickr.

Ensure truly secure data communications by downloading Wickr, the communication and collaboration platform protected by end-to-end encryption.