Old Java Card vulnerabilities resurface in eSIMs
Research focusing on eSIM security has led to the discovery of a hacking method that could have serious implications.
Embedded SIMs, or eSIMs, have become increasingly common. They eliminate the need for physical SIM cards in mobile phones and other IoT devices that require cellular communications. One important component of the eSIM ecosystem is the embedded Universal Integrated Circuit Card (eUICC), which enables remote SIM provisioning and the use of multiple profiles for connecting to different mobile networks.
Security Explorations, the research lab of Poland-based AG Security Research, has conducted an extensive analysis of eSIMs and eUICC and found vulnerabilities that could be exploited to clone a target’s eSIM and spy on their mobile communications.
The research has focused on a widely used Kigen eUICC card. Kigen, which claims to have enabled two billion SIMs in IoT devices, has been notified of the findings and it has taken steps to mitigate the risk of attacks.
The company has published an advisory describing the potential impact of the vulnerabilities, as well as mitigations. While Kigen has classified the issue as having medium impact, Security Explorations noted that it received a $30,000 reward from the company for its work.
GSMA, the organization that represents the interests of mobile network operators around the world, has shared guidance for profile owners, eUICC manufacturers, device vendors, and application developers in response to the eSIM hacking research.
It’s worth noting that while the Security Explorations project focused on Kigen products, eUICC/eSIM chips from several other vendors may be vulnerable to similar attacks as the underlying issue is related to a series of vulnerabilities found in Oracle’s Java Card technology.
The Java Card flaws were disclosed by Security Explorations in 2019, but Oracle and SIM card manufacturers using the technology downplayed their potential impact at the time.
Building on that research, Security Explorations looked into the security of eSIM over the course of several months.
In order to conduct an attack, the attacker needs temporary physical access to the device with the targeted eSIM. The goal is to extract a key that allows the installation of a malicious Java Card application.
Adam Gowdiak, the CEO and founder of AG Security Research, explained for SecurityWeek that once the keys are obtained, they can be used to install malicious apps using over-the-air (OTA) mechanisms and physical access is no longer required, as demonstrated by a proof-of-concept he created.
Once a malicious application has been installed, it can enable the attacker to compromise the security of the chip, which was built with the assumption that it cannot be compromised.
The attacker can obtain eSIM profile data (used by different mobile operators for authentication on their network), which can be leveraged by well-resourced threat actors (eg, nation state hackers) to eavesdrop on communications, Gowdiak warned.
It’s also possible for an attacker to download eSIM profiles in clear text and use them for eSIM cloning. The researcher demonstrated the potential impact by cloning an Orange Poland eSIM profile, which led to messages and calls going to the device with the cloned eSIM rather than the original device. Other mobile network operators are likely impacted as well.
Gowdiak also noted that it may be possible for an attacker to create a backdoor on an eSIM chip, and mobile operators and phone vendors would likely have no means of detecting it.
Lastly, an attacker may also be able to use the exploit to brick eSIM chips — the researcher said he damaged five cards during his research.
Oracle does not seem very concerned about the latest research either, according to Security Explorations. However, the security firm believes the latest attack may have been prevented if Oracle had taken the 2019 bugs more seriously.
Security Explorations has created a toolset for determining whether a Java Card VM used by an eSIM is vulnerable to attacks. The toolset also enables the extraction of the required key, but this functionality is specific to Kigen cards, and a custom exploitation method is likely needed for each other type of eUICC card.
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