Security and technology researchers from the University of Birmingham and Fuzor, at the OzoneX VOT security conference in Baltimore, warned that malicious or compromised SIM cards create serious and overlooked security threats for cellular devices.
This threat can silently take over phones, electric vehicle chargers, and critical industrial equipment. Using the specialized Katana tool, researchers tested 26 representative devices including smartphones and IoT modules in EV chargers and industrial equipment.
Dr. Marius Münch, an assistant professor of computer science at the University of Birmingham, says: “The interesting part is that proactive SIM capabilities and the resulting attack surface are explicitly defined in cellular communication specifications, which leads to ‘spec-compliant’ attacks.”
The flaw is not a coding bug, but a feature. An internal feature called “proactive SIM” allows the SIM card to issue direct commands to the device modem.
According to ITNA and citing Interesting Engineering, among these capabilities lies a powerful legacy: AT commands. To demonstrate the danger of this feature, researchers used the Katana tool and found that attackers can gain full control of devices without any user interaction.
They were able to execute arbitrary code, steal sensitive hardware identifiers, force locked Android phones to open malicious links, downgrade connection security from 4G to vulnerable 2G networks, and remotely disconnect or power off devices.
Notably, smartphones are not the only target. Industrial routers, EV chargers, and automotive systems that are designed like fortified bastions have all left a large backdoor open: the SIM slot. An attacker does not always need physical access to swap the SIM card.