5G Inherits Some 4G Vulnerabilities

• By Karen Epper Hoffman
• Dec 09, 2019

Commercial 5G mobile networks are only just becoming available, with highly developed use cases for improving autonomous automobiles navigation and smart-sensor networks, and new vulnerabilities and security requirements are already emerging. Although 5G networks promise improvements in device authentication, traffic encryption, privacy protections for device IDs and credentials, many of the security protocols and algorithms for 5G are being ported from the previous 4G standard. That means these newer networks may suffer from many of the same vulnerabilities, at least in the short-term.

Indeed, researchers have found that cyber criminals can exploit device fingerprinting for targeted attacks as well as the possibility of man-in-the-middle offensives, even in 5G, according to Altaf Shaik, principal researcher at Kaitiaki Labs. Speaking on “New Vulnerabilities in 5G Networks” at the recent Black Hat USA conference, Shaik discussed multiple ways in which 5G networks could be compromised.

For example, since 5G networks are made up of base stations covering a specific area, they connect to a mobile edge cloud, which in turn connects to the core network. To get to a carrier network, 5G devices send device-capability data to the base station, which passes it on along the chain for eventual authentication to the core network. This data can incorporate include information about voice calling, SMS ability, vehicle-to-vehicle communication support, frequency bands used, and the device category as well as radio requirements.

At Black Hat, Shaik pointed out that in forthcoming 5G networks, the device capability information is sent to the base station before any security is layered onto the connection. Over-the-air security includes encryption of traffic from the endpoint to a base station; but since the device capabilities are transmitted prior to that taking effect, hackers can see this information in plain text. Hence, according to Shaik, 5G networks could still allow for a few types of attack:

Mobile network mapping (MNmap): Using real devices and commercial networks in Europe and the United States, Shaik's research team was able to sniff the information sent by the device in plain text and use it to create a map of devices connected to a given network. “We set up a fake base station to receive the capabilities of the devices,” Shaik said. “We categorized maker, model, OS, use case and version. This allows you to identify any cellular device in the wild. You can tell if a device is Android or iOS, if it’s IoT or a phone, if it’s a car modem, a router, a USB dongle, or a vending machine.”

That information paves the way for targeted attacks against a specific device or a whole class of devices, Shaik said. “You can plan a targeted attack against a certain kind of device – such as those used in field testing, or military devices. There’s also a privacy aspect here because you can link the [mobile subscriber ID] to a specific person.”

MiTM attacks: Man-in-the-middle attacks become relevant when hackers hijack the device information before security is applied -- as it is being sent to the base station. “You can take this data and modify the capabilities” of the device, Shaik said. Attackers could alter the frequency band information for a device to prevent handovers or roaming; or they could disable voice over LTE, which makes a phone revert to 3G/2G voice calling. These changes can also force the draining of IoT device batteries.

In his tests, Shaik reported that 22 out of 32 tested LTE networks worldwide were vulnerable to these types of attacks, with most of the tampering persisting for an average of seven days. He reported his findings to standards organizations and hopes to see fixes implemented by vendors next year.

“This is a problem, a fundamental issue that was ported from 4G,” Shaik said. “But in 5G, there are more use cases and more capabilities that define exactly what kind of device it is, making targeting that much easier.”