**Reynolds Ransomware Uses BYOVD Driver to Evade EDR Tools**
*What CISOs and Security Leaders Need to Know About This Alarming Threat Tactic*
**Introduction**
Imagine this: your endpoint detection and response (EDR) tools are fully deployed, your security team is confident, and your SIEM shows no alerts. Yet, deep within a system, ransomware is methodically locking files and disabling defenses—undetected. That’s the new frontier we’re facing with threats like the Reynolds ransomware strain.
According to a recent report by The Hacker News [(source)](https://thehackernews.com/2026/02/reynolds-ransomware-embeds-byovd-driver.html), Reynolds ransomware has started embedding a Bring Your Own Vulnerable Driver (BYOVD) tactic to disable security tools and slip under the radar of EDR systems. This isn’t just a clever hack—it’s a calculated evolution in ransomware deployment, one that directly undermines modern security investments.
If you’re a CISO, CEO, or security strategist, this development should be a red flag. This post breaks down how the BYOVD technique works, why it’s particularly dangerous, and—critically—what practical steps you can take today to defend your organization against this emerging threat. By the end, we aim to turn this urgent warning into a concrete response plan.
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**How BYOVD Works: Exploiting Trust in Drivers**
Let’s start by unpacking the core vector: BYOVD. In short, attackers exploit signed but vulnerable kernel-mode drivers to gain privileged access, disable security tools, and move freely.
Here’s what makes this method so effective:
– **Signed drivers are inherently trusted by Windows**. When malware loads a legitimate—though vulnerable—driver, the system allows it because it’s signed.
– **This specific Reynolds ransomware variant embeds the RTCore64.sys driver**, previously used in other BYOVD attacks like those linked to BlackByte and LockBit.
– Once loaded, the driver can be used to disable or remove critical EDR components, tamper with kernel memory, and escalate privileges.
To put it in perspective, a 2023 Microsoft report noted that over 35% of ransomware groups now incorporate BYOVD techniques into their toolkits—a number that’s clearly growing.
**Actionable Tips**:
– Perform a thorough audit of all drivers running in your environment. Look especially for older versions known to be vulnerable.
– Leverage tools like Microsoft’s Driver Blocklist, available via Defender Application Control (WDAC), to prevent known bad drivers from loading.
– Include BYOVD-specific checks within your red team exercises. Ensure your detection response plans account for this vector.
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**Why This Evasion Technique Bypasses EDR and AV**
EDR technologies are generally excellent at detecting user-space malicious activities. But BYOVD is different—it operates at the kernel level with trusted, signed drivers.
Here’s why Reynolds ransomware is skipping past EDR:
– **It disables the kernel-mode callback routines** that EDRs use to monitor process execution and file operations. Without these, the EDR is effectively blind.
– Some EDRs rely on kernel hooks that are easily disrupted or removed once a vulnerable driver is in use.
– Traditional antivirus tools scan for known malware signatures—but not for vulnerable drivers used as enabling components.
Security teams are often surprised that a technique this low-level can still be so effective. But consider this: according to Mandiant’s Threat Intelligence, more than 60% of successful ransomware intrusions in 2025 involved some form of security tool tampering.
**Actionable Tips**:
– Implement kernel patch protection (PatchGuard on Windows) and Secure Boot to reduce the risk of unauthorized driver loading.
– Monitor for driver installation events and privilege escalation patterns that deviate from baselines.
– Roll out EDR with kernel-mode protection (e.g., CrowdStrike Falcon or SentinelOne Singularity) that can detect even low-level tampering.
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**Mitigation Isn’t Optional: Prioritize Preemptive Defense**
The Reynolds ransomware tactic serves as a reminder: advanced threat actors no longer “bypass” defense—they dismantle it.
Now is the time to harden your infrastructure with defense-in-depth principles focused on both visibility and prevention. Here’s a layered approach:
– **Zero Trust for Drivers**: Don’t assume “signed” equals “safe.” Develop a allowlist policy for drivers—not just by vendor but by version.
– **Threat surface reduction**: Disable unused device drivers or services. The fewer drivers running, the fewer opportunities for BYOVD attack.
– **Procurement coordination**: Work closely with IT procurement teams to ensure that drivers associated with new hardware or software are scrutinized for vulnerabilities.
A misstep in this area isn’t just a security issue—it’s a business continuity risk. IBM’s 2025 Cost of a Data Breach report revealed the average ransomware breach now exceeds $5.3 million in remediation costs, excluding downtime and ransomware payments.
**Actionable Tips**:
– Review the vendor’s patch history before updating or installing third-party drivers.
– Integrate threat intel feeds that track driver misuse and incorporate rules into your SIEM.
– Train incident response teams on identifying malicious driver use and potential EDR evasion signs.
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**Conclusion**
The Reynolds ransomware campaign is a warning shot: adversaries are increasingly adept at turning our systems’ trust mechanisms against us. BYOVD isn’t new—but its resurgence in modern ransomware campaigns, like Reynolds, signals a larger issue for enterprise defenders. Relying solely on perimeter and endpoint tools is no longer sufficient when threats operate at or below the kernel level.
We encourage security leaders to take this threat seriously. Now is the time to re-evaluate your assumptions about driver trust, bolster your EDR capabilities, and update defensive playbooks to include BYOVD-specific scenarios.
**Don’t wait for ransomware to test your defenses—test them yourself.**
If you haven’t yet, start by auditing your currently installed drivers across all endpoints. Then, work with your security teams to implement the Microsoft blocklist, monitor driver activity, and red team your kernel-level defense strategy. The Reynolds campaign is a wake-up call—but with the right actions now, your organization can stay ahead of the curve.
For further technical details, consult the full analysis on The Hacker News: https://thehackernews.com/2026/02/reynolds-ransomware-embeds-byovd-driver.html.
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