New Rowhammer Attack Bypasses DDR5 Security, Putting Modern Systems at Risk
For years, the evolution of computer memory has been a story of increasing speed and reliability. The latest standard, DDR5, was introduced not just with performance boosts but also with built-in hardware mitigations designed to thwart a notorious class of hardware vulnerability known as Rowhammer. It was believed to be a significant step forward in securing the fundamental building blocks of our computers.
However, recent security research has demonstrated that these protections are not foolproof. A new, sophisticated Rowhammer attack has been developed that successfully bypasses the security features of DDR5 memory, proving that even the latest hardware is vulnerable to this persistent threat.
What Exactly Is a Rowhammer Attack?
To understand the significance of this development, it’s essential to know what Rowhammer is. At its core, Rowhammer is a hardware exploit that takes advantage of an electrical interference issue in modern high-density DRAM memory chips.
Memory is organized into a grid of rows and columns. When a processor repeatedly and rapidly accesses a specific row of memory—an action known as “hammering”—it can cause a tiny electrical disturbance. This disturbance can be strong enough to flip the bits (changing a 0 to a 1, or vice versa) in adjacent, physically close memory rows, even without directly accessing them. This phenomenon is called bit-flipping.
While a single random bit-flip might cause a simple crash, a targeted attack can allow a malicious actor to change critical data in memory, leading to a complete system takeover.
The DDR5 Promise: Why It Was Supposed to Be Safe
Memory manufacturers have long been aware of the Rowhammer problem. To combat it, DDR5 memory modules were engineered with on-chip mitigations. The most prominent of these is a mechanism called Target Row Refresh (TRR). In theory, TRR is designed to detect when a memory row is being accessed too frequently and proactively refresh the neighboring rows before their data can be corrupted.
This built-in defense was a key selling point for DDR5, promising a new era of resilience against hardware-level memory attacks. It was widely assumed that this would make practical Rowhammer exploits a thing of the past.
The Breakthrough: How the New Attack Bypasses Protections
Security researchers have discovered that the TRR mechanisms in today’s DDR5 chips have exploitable weaknesses. By analyzing the physical properties of the memory chips, they were able to devise new, complex access patterns that the on-chip defenses do not recognize as a threat. Instead of simply hammering one row, the new technique involves a more intricate sequence of memory accesses that effectively confuses the mitigation logic.
The most alarming aspect of this discovery is how the attack can be delivered. Researchers have demonstrated that this attack can be triggered remotely through a web browser using JavaScript. This means a malicious advertisement or a compromised website could be enough to launch a Rowhammer attack on a vulnerable system, requiring no prior access or user interaction beyond visiting a web page.
Why You Should Be Concerned: The Impact of a Successful Attack
A successful Rowhammer attack is not a minor issue; it’s a critical security failure. By strategically flipping bits in protected areas of memory, an attacker can achieve devastating results:
- Privilege Escalation: An attacker running a low-privilege application (like a sandboxed browser script) could alter memory belonging to the operating system’s kernel, granting themselves the highest level of administrative access.
- Security Bypass: The attack can be used to disable security features, break out of virtual machines, or compromise cryptographic keys stored in memory.
- Full System Control: Ultimately, a successful exploit can give an attacker complete control of a system, allowing them to steal data, install ransomware, or use the machine as part of a botnet.
How to Protect Your System: Actionable Security Measures
While this vulnerability exists at the hardware level, there are steps you can take to mitigate the risk. The responsibility for a full fix lies with manufacturers, but proactive defense is crucial.
- Update Everything: Ensure your operating system, web browsers, and all software are kept fully up to date. Software patches are often released to make hardware exploits more difficult to trigger.
- Monitor for Firmware Updates: The most effective patches for this issue will come from your computer or motherboard manufacturer in the form of BIOS/UEFI updates. These updates can tweak memory controller settings to make Rowhammer attacks harder to execute. Check your manufacturer’s support website regularly.
- Practice Safe Browsing: Since this exploit can be delivered via the web, exercise caution online. Use a reputable ad-blocker and avoid visiting untrusted websites.
- Enable Advanced Security Features: Modern operating systems like Windows and Linux offer kernel and memory integrity features. Ensure these are enabled, as they can provide an additional layer of defense against memory-based attacks.
The discovery of a working Rowhammer exploit for DDR5 is a stark reminder that in the world of cybersecurity, no system is ever completely secure. It highlights the continuous cat-and-mouse game between attackers and defenders, proving that vigilance and ongoing research are our best defenses against emerging threats.
Source: https://go.theregister.com/feed/www.theregister.com/2025/09/17/ddr5_dram_rowhammer/
