Mitigating SIM Card Data Breaches & Lowering Enterprise Mobile Risk

2 mins.

May 1, 2025

Overview

The SIM card is a critical component of the mobile network, playing a key role in authentication, encryption, and access control. As mobile networks evolve, particularly with the deployment of LTE and 5G technologies, stringent security measures have been implemented to protect user data.
Despite these efforts, SIM card data breaches may still occur, driven by evolving attack vectors and increasingly sophisticated threats. To mitigate these risks and losses, it is essential to prioritize identity verification and implement robust operational security. This includes proactively monitoring suspicious device activities, employing real-time detection of anomalous SIM behavior or identity mismatches, and utilizing a Zero Trust Architecture (ZTA) for connected devices to prevent identity compromises turning into even more impactful attacks.

Overlooking the risk of SIM data breaches within private, self-managed networks can expose enterprises to serious risk. A compromised SIM can result in unauthorized access, identity spoofing, and uncontrolled device connections, leading to operational disruptions and potential data breaches.

Attack Vectors

SIM data breaches
Although the SIM card itself is a highly secure and trusted module, user authentication data stored within the 5G core system can still be exposed through malicious activities. In the event of a SIM data breach, attackers may gain access to sensitive information such as phone numbers, IMSI (International Mobile Subscriber Identity), ICCID (Integrated Circuit Card ID), authentication keys, and user IDs. Once in possession of this information, attackers can impersonate the victim, gaining access to their accounts, sensitive communications, and even banking or financial services.

SIM cloning/ duplication
SIM cloning is when someone illegally copies the data from your original SIM card onto another SIM card. This creates a duplicate SIM, allowing the attacker to receive your phone calls and SMS messages, bypass two-factor authentication (2FA), or hijack your mobile identity. SIM cloning usually requires access to your SIM’s unique keys (such as the IMSI), which can be obtained through data breaches.

Identity theft
In this type of attack, hackers obtain personal information about the target, often through phishing or data breaches, and use it to convince the mobile carrier to transfer the target’s phone number to a new SIM card under their control. Once in possession of the new SIM card, the attacker gains access to the victim’s phone number, intercepts sensitive communications, and potentially commits identity theft or financial fraud

SIM fraud
SIM fraud occurs when hackers use stolen SIM data to engage in various forms of deception, including fraudulent calls, illegal mobile transactions, or abuse of mobile network resources. Hackers exploit the vulnerabilities in the SIM management process, sometimes acquiring SIM data through attacks on telecom networks, to carry out fraudulent activities.

Mitigation Plan

Given the growing risks associated with SIM data breaches, it is essential for enterprises to implement effective mitigation strategies based on real-time monitoring, detection, and Zero Trust Architecture (ZTA) principles to proactively address potential risks.

A Zero Trust Architecture (ZTA) is an essential framework for safeguarding mobile networks. It operates on the principle that no device or user should be trusted by default, regardless of whether they are inside or outside the network environment. Every request, whether from a device or user, must be identified and verified before access is granted. This ensures that even if a SIM card’s data is compromised, attackers cannot gain unauthorized access to the network or sensitive data without first undergoing thorough identification and verification processes. ZTA also mitigates the risk of SIM swap attacks for unauthorized users to manipulate the system.

CTOne Can Help

Our SIM-based endpoint protection solution adds a critical layer of zero-trust security without requiring integration into core network systems. During initial onboarding, it collects identifiers such as IMEI, IMSI, and other device information, using this combination to create a unique identity. Through identity binding, the system ensures only valid device-SIM pairings are allowed. Unauthorized access, such as cloned/duplicated SIMs (without our solution integrated) or corporate SIMs used in unauthorized devices, will be automatically blocked. Additionally, if an unauthorized cellular device attempts to access the radio network or send malicious traffic, our joint defense feature automatically detects and isolates the device from the mobile core network.

About CTOne

CTOne delivers an end-to-end solution, securing both the endpoint and network layers individually and in concert. The solution, called Trend Micro Mobile Network Security powered by CTOne, is an end-to-end security solution that supports zero trust architecture (ZTA) & joint defense strategies, providing a comprehensive cybersecurity solution covering visibility & enforcement across mobile endpoints, RAN, MEC, 5GC, and data networks.