Ledger Finds Critical, Unfixable Vulnerability in Popular MediaTek Smartphone Chip
An unpatchable security flaw in a widely deployed smartphone processor from Taiwan-based MediaTek can allow an attacker to seize complete control of a device using a precisely timed electromagnetic attack. The issue was disclosed in new research published by hardware wallet maker Ledger.
The weakness resides in the chip’s boot ROM—the immutable code that runs at the very earliest stage of the startup sequence. Because boot ROM is burned into silicon at manufacture and cannot be overwritten, this class of bug cannot be corrected with a software update or a conventional security patch.
Ledger’s security research unit, the Donjon team, analyzed the MediaTek Dimensity 7300 (MT6878), a 4‑nanometer system-on-chip used across a range of Android smartphones. During their tests, they demonstrated that by carefully injecting electromagnetic pulses at specific moments in the chip’s boot process, they could sidestep memory-access protections and break into EL3, the highest privilege level defined in the ARM architecture.
Once code is running at EL3, it effectively has god‑mode access to the device: it can override security checks, alter protected memory, and potentially take control of any other software component running on the system, including secure environments that are normally isolated from Android and apps.
Why the Flaw Is “Unpatchable”
The defining factor that makes this vulnerability particularly serious is its location. Boot ROM is designed to be the system’s foundation of trust: it initializes hardware, verifies cryptographic signatures on later-stage bootloaders, and sets up the security model that everything else depends on.
Because this code is physically embedded in the chip:
– It cannot be updated over the air.
– Device manufacturers cannot fix it with a firmware or OS upgrade.
– Mitigations are limited to external safeguards or hardware revisions in future chip batches.
That means every device shipping with the affected boot ROM logic carries this flaw for its entire lifecycle.
How the Attack Works in Practice
The attack shown by Ledger’s team relies on electromagnetic fault injection (EMFI). In simplified terms, the researchers positioned specialized equipment near the chip and fired brief electromagnetic pulses at extremely precise times during the boot sequence. These pulses are tuned to momentarily disrupt the chip’s internal operations.
If the timing is right, the disturbance can cause the processor to:
– Misread a value in memory,
– Skip a critical conditional check,
– Or branch into code that should never be reachable by an attacker.
According to Ledger’s findings, this allowed them to bypass memory-access controls and climb the privilege ladder until they reached EL3. From there, they could subvert the entire security model the chip is supposed to enforce at boot.
This type of attack requires physical proximity and specialized tools; it is not something that can be executed remotely over the internet or through a normal app. However, for high-value targets—such as individuals holding significant cryptocurrency, sensitive corporate data, or state secrets—this bar is not necessarily prohibitive.
Implications for Crypto Users and Hardware Security
The research is especially relevant to the crypto ecosystem because many users rely on smartphones for managing wallets, keys, and exchanges. If a device’s lowest-level trust anchor can be compromised:
– Secure elements or trusted execution environments (TEEs) may be weakened or bypassed.
– Seed phrases or private keys that are believed to be in “secure” storage may become reachable to an attacker with physical access and the right equipment.
– Anti-tampering guarantees offered by mobile devices become less trustworthy for sophisticated adversaries.
Ledger’s involvement underscores why dedicated hardware wallets remain recommended for storing substantial amounts of cryptocurrency. A purpose-built wallet is designed around strict physical and logical isolation, whereas a general-purpose smartphone has a much broader attack surface and more dependencies on complex chips and firmware.
What This Means for Phone Owners Today
For everyday users, the discovery does not mean hackers can suddenly hijack phones en masse. Several constraints still apply:
– The attack is physical: an adversary needs access to the device and EMFI gear.
– It requires expertise and fine-tuned timing; this is not a mass-exploitation tool in its raw form.
– Many routine threats—phishing, malware, SIM swapping—remain far easier and cheaper for criminals.
However, the finding does change the risk picture for certain scenarios:
– High-profile individuals, activists, executives, and crypto-rich users face higher incentives for targeted, lab-grade attacks.
– Confiscated devices in border or law-enforcement contexts could, in theory, be subjected to this type of analysis to weaken or bypass device protections.
– Long-term confidentiality of data and keys stored on affected devices is harder to guarantee against well-resourced adversaries.
Why Boot ROM Vulnerabilities Are So Significant
Security engineers view boot ROM as the root of a device’s trust chain. If that root is flawed:
– Every layer above it (bootloaders, OS, secure apps) is built on compromised assumptions.
– Even perfectly written application code can be undermined if the hardware below it can be coerced into lying about what’s happening.
– Attackers can often disable or spoof later-stage mitigations, such as secure boot verification and integrity checks.
Unlike a bug in an app or OS, which can be rolled back with a patch, a boot ROM vulnerability effectively becomes part of the hardware’s permanent identity. That’s why chip vendors usually invest heavily in validating this code before mass production; when something slips through, the consequences can stretch across entire product generations.
Mitigations and What Manufacturers Can Still Do
Although the bug itself cannot be “fixed” on already-shipped chips, there are partial mitigations and strategic responses:
– Future silicon revisions: MediaTek can correct the boot ROM logic for new manufacturing runs, reducing the number of future devices exposed.
– Board-level defenses: Device makers can design phone interiors to complicate physical access to the chip, making precise EMFI positioning harder.
– Additional integrity checks: Higher-level firmware might attempt extra verifications, although anything above boot ROM ultimately inherits its weaknesses.
– Usage guidance: Vendors and security companies can warn high-risk users about the physical nature of the vulnerability and recommend stronger operational security for devices storing sensitive keys.
For security-sensitive individuals, minimizing the time a critical phone is out of their control and using separate, offline devices for long-term key storage are practical risk-reduction strategies.
Broader Lessons for the Chip Industry
This incident highlights several broader issues for the semiconductor and mobile ecosystem:
– Growing complexity: Modern system-on-chips pack more features into ever-smaller processes, increasing the difficulty of verifying every security-critical path.
– Physical attacks are mainstreaming: Techniques like fault injection, side-channel analysis, and EMFI, once confined to academic labs, are now more accessible to private security shops and attackers with moderate budgets.
– Unpatchable bugs are existential risks: A single mistake in boot ROM can effectively undermine an entire product line, with no easy recourse once millions of devices are in circulation.
As more financial and identity-critical functions move to phones—payments, authentication, digital IDs—the cost of low-level hardware flaws rises. The industry is increasingly pressured to treat hardware security on par with software security in both investment and transparency.
Practical Advice for Crypto Holders and Power Users
For users managing digital assets on smartphones, the findings from Ledger’s research support a few concrete recommendations:
1. Use dedicated hardware wallets for significant crypto holdings, and reserve phones for smaller, spending-level balances.
2. Treat physical access as a serious risk—do not leave critical devices unattended in high-risk environments for extended periods.
3. Enable all available device protections such as secure lock screens, full-disk encryption, and biometric authentication, understanding they are not absolute but still raise the bar.
4. Segment your risk: Avoid concentrating all wallets, authentication apps, and backup information on a single phone, especially if you travel frequently or are a high-value target.
The Road Ahead
The MediaTek Dimensity 7300 case is unlikely to be the last time a fundamental hardware flaw surfaces in a mainstream consumer device. As research tools improve and more security teams scrutinize low-level components, additional weaknesses will almost certainly come to light.
The key question for the ecosystem is how quickly chipmakers, device vendors, and the security industry can:
– Acknowledge such flaws transparently,
– Provide realistic guidance on impact and mitigation,
– And evolve designs to make future hardware more resilient against both logical and physical attacks.
For now, Ledger’s discovery serves as a reminder that even the most advanced smartphones rest on foundations that are not infallible—and that truly robust protection of critical assets still benefits from specialized, hardened hardware beyond the everyday mobile device.