Backdrop.

We have all seen the familiar scene: A detective types a phone number into their computer, and within seconds, a map appears showing the exact location of the suspect. From the algorithmic omniscience of Person of Interest to the high-tech command centers of 24, television drama has embraced hidden mobile network backdoors as a cornerstone of modern surveillance storytelling.​

Real-world phone tracking is "far more complex and nuanced than what is depicted on screen," typically requiring warrants and facing significant technical limitations that television rarely acknowledges.

The gap between Hollywood's instant gratification and actual investigative procedures reveals how popular culture shapes our understanding of privacy, technology, and state surveillance capabilities.

However, it is entirely possible and has the potential to do so much more than just pinpoint your location.

What the baseband processor does

Every modern smartphone contains two separate computers. The main processor runs the operating system, apps, and the user interface that you see and interact with. The second computer, called the baseband processor, is dedicated solely to handling all cellular radio functions. It manages voice calls, text messages, mobile data, and the signaling that keeps the phone connected to the network. Because it operates independently, the baseband runs its own real-time operating system and firmware that are never visible to the user.

Why the baseband is a security concern

The baseband processor has privileged access to the phone's hardware. It can read and write the device's main memory through direct memory access channels, and it controls the radio that carries every piece of data entering or leaving the phone. The firmware that runs on the baseband is proprietary; manufacturers do not publish its source code, and users cannot inspect or modify it. This combination of high privilege, closed code, and continuous exposure to the public cellular network creates a powerful attack surface.

Real-world vulnerabilities

Over the past few years, multiple critical flaws have been discovered in baseband firmware from the major chipset makers. These flaws include buffer overflows, out-of-bounds writes, and logic errors in the handling of 5 G, LTE, and VoLTE messages. Exploits targeting these bugs can be delivered remotely without user interaction. An attacker needs only the victim's phone number and the ability to send a specially crafted network packet.

Successful exploitation gives the attacker full control of the baseband, allowing them to read passwords, encryption keys, and any data passing through the radio. It also enables the attacker to persist on the device even after the operating system is reinstalled or the phone is reset.

How attacks are carried out

Two primary delivery methods are used:

1. Rogue cellular towers (IMSI‑catchers). A device that pretends to be a legitimate cell tower broadcasts a stronger signal, causing nearby phones to connect to it. The attacker can then downgrade the connection to older, less secure protocols and inject the malicious packets that trigger the baseband bug.
2. Internet‑to‑baseband exploits. Certain vulnerabilities can be triggered through ordinary mobile data connections, such as Voice‑over‑LTE or Wi‑Fi calling. The attacker sends a malformed packet over the internet that reaches the baseband and triggers the flaw.

Both methods require no clicking, no app installation, and no special permissions from the user.

The update problem

Baseband firmware updates follow a complex chain: the chipset maker creates a patch, the device manufacturer integrates it, the carrier validates it, and finally the update is pushed over the air. This coordination introduces delays of weeks or months. Many mid‑range and budget phones stop receiving baseband updates after two years, leaving known vulnerabilities unpatched indefinitely. Even flagship devices may receive updates months after a flaw is publicly disclosed.

What the baseband cannot do

Although the baseband can access the main memory, modern devices incorporate hardware safeguards such as input‑output memory management units (IOMMU) and secure address space controllers. These mechanisms restrict the baseband's DMA to approved memory regions, preventing unrestricted reads of the most sensitive data.

However, a vulnerable baseband can still bypass many software protections, thereby increasing the risk.

Practical steps you can take today

1. Choose a phone with a long update commitment. Devices that receive five years of security updates, such as recent Pixel models or the latest iPhones, are far less likely to remain vulnerable for long periods.
2. Use end‑to‑end encrypted communication. Applications like Signal encrypt messages on the device before they reach the radio, so even if the baseband is compromised the content remains unreadable.
3. Turn off cellular radios when they are not needed. Switching to airplane mode disables the baseband entirely, eliminating the attack surface for that period.
4. Keep the operating system current. While OS updates do not patch the baseband directly, they often include mitigations that make it harder for a compromised baseband to affect the rest of the system.
5. Avoid custom ROMs on devices that do not receive baseband updates. Installing a custom Android build does not change the baseband firmware, but it may remove the manufacturer's verified boot protections.
6. Monitor the baseband version. Most phones display the baseband version in the settings menu. Compare it with the manufacturer's release notes to ensure you are not running an outdated firmware.

Recommendations for manufacturers and carriers

• Implement mandatory IOMMU protection on all devices, ensuring the baseband can access only explicitly approved memory regions.
• Separate signing keys for the application processor and the baseband, and rotate them regularly to limit the impact of a key compromise.
• Provide transparent baseband version information in the user interface and allow users to manually check for updates.
• Accelerate the patch pipeline so that critical baseband fixes reach devices within thirty days of discovery.
• Require explicit user consent for any over-the-air baseband update that is not an emergency security patch.

Bottom line

The baseband processor is a hidden but critical component that controls every radio communication on your phone. Its privileged access, proprietary firmware, and exposure to the public cellular network make it an attractive target for sophisticated attackers. Real-world exploits have demonstrated remote, zero-interaction compromise of the baseband, granting attackers full control of the device. While modern hardware adds layers of protection, many devices—especially older or budget models—remain vulnerable for extended periods.

By selecting a device with a strong update policy, using encrypted communication apps, and disabling radios when they are not needed, everyday users can dramatically reduce their exposure. Manufacturers and carriers must tighten hardware isolation, streamline patch distribution, and increase transparency to protect the billions of smartphones that rely on this unseen processor.