The standards body in charge of 5G wireless network security is drafting new requirements for addressing recently reported vulnerabilities in the technology that impact both end user devices and operator infrastructure.
The new requirements - which are expected to become available from the 3rd Generation Partnership Project (3GPP) with the next release of the 5G standard - specify how certain device information should be handled on the network.
Security researchers at the Technical University of Berlin and Kaitiaki Labs discovered the vulnerabilities earlier this year and presented details of their work at Black Hat USA.
The problem, according to the researchers, is that when a mobile device registers on a 5G network, details about the device and its technical capabilities are exchanged in an insecure manner. This gives attackers a way to intercept the device capability data and use it to identify specific devices, degrade performance, and drain batteries.
"The vulnerabilities are present in the 4G and 5G registration procedure that happens every time a device is turned on with SIM card," says Altaf Shaik, principal security researcher at Kaitiaki Labs and PhD student at the Technical University of Berlin.
During this procedure the device conveys its capabilities — such as its throughput categories, app data, radio protocol support, security algorithms, and carrier info — to the network, either in plain text or prior to establishing over-the-air security. This opens the procedure to both passive attacks and man-in-the-middle attacks, Shaik says.
"Attackers can obtain the capabilities and fingerprint specific devices or can modify the capabilities and cause downgrade or DoS [denial-of-service] attacks," he says.
Potential dangers include attackers being able to track high-value devices such as those belonging to politicians or the military, or downgrading devices to less secure networks and causing poor quality of service overall.
4G LTE Affected as Well
Shaik identified the vulnerabilities in the current 3rd Generation Partnership Project (3GPP) standards for mobile telephony. All devices supporting 4G LTE and upcoming 5G standards are impacted.
Shaik and fellow researcher Ravishankar Borgaonkar from Kaitiaki Labs built an experimental setup consisting of two i7 PCs running Linux and two software-defined radio modules to demonstrate how attackers could exploit the vulnerabilities.
Shaik says the task of fingerprinting mobile devices using the vulnerabilities is similar to using the Nmap network-scanning tool on the Internet. By intercepting and analyzing device capabilities, an attacker can identify device model, device type, manufacturer, applications, operating system version, and other details.
The two researchers used their experimental set up to similarly show how an attacker could use a man-in-the-middle attack to make a device appear less powerful than it really is to the network - thereby effectively neutralizing its high-speed capabilities. In experiments the researchers conducted with an iPhone 8 and a Nighthawk M1 mobile router, the researchers were able to degrade device performance from 27 Mbps to 3 Mbps. Of the 30 mobile networks that Shaik and Borgaonkar tested for the issue, 21 were impacted.
Similarly, attackers can cut down the effective battery life of narrowband IoT devices by a factor of five by disabling the IoT functionality in the devices and making them operate like a traditional smartphone, Shaik says.
The 3GPP standards body is currently working on introducing a requirement that device capability information is protected and will be sent to the network only after a secure session has been established, he adds.
High Impact on Unattended IoT
In a change request form on the 3GPP website, the organization described the vulnerabilities as exposing user equipment to attacks that can downgrade device throughput, or to trace specific devices.
"Since the [User Equipment] capabilities are persistently stored in the network, the impact of the attack can last for weeks, or until the UE is power cycled," the standards body said. It added that such attacks could have a particularly high impact on unattended IoT devices.
Rolando Hernandez, vice president at Valid, a Brazilian provider of various mobile technology and data services, says the security issues surrounding 5G exist at both the network and the device level. "Protection of the subscriber’s identity is one of 5G’s biggest security challenges," he notes.
"The easiest fix to this challenge is to implement the subscription concealed identifier (SUCI), which adds an additional layer of security," he says. The SUCI prevents a malicious actor from tracking mobile subscribers because the subscriber identifier in a 5G SIM card is encrypted such that only the 5G network is able to match the real subscriber, he says.
"The standards bodies are a carrier's best bet for mitigating the vulnerabilities associated with 5G networks," he notes. "When any vulnerability is discovered and improvements are suggested, standardization entities launch a new version of the standards, indicating the changes that manufacturers will need to implement in their equipment or devices."
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