Topic starter
09/07/2026 3:31 pm
TL;DR: Reynolds ransomware uses a Bring Your Own Vulnerable Driver pattern to load NSecKrnl.sys, gain kernel-level execution, terminate AV and EDR processes, and then encrypt local and network drives, according to Gurucul. When ransomware can disable defenses before encryption begins, detection, containment, and identity-aware control validation all become time-critical.
Editorial analysis by NHI Mgmt Group, based on content published by Gurucul: “Reynolds Ransomware: BYOVD Abuse of NSecKrnl.sys (CVE-2025-68947) for Kernel-Level Defense Evasion”.
Key questions
Q: What breaks when a vulnerable signed driver is loaded on an endpoint?
A: The normal trust boundary breaks because the attacker gains a kernel-level path that can bypass user-mode restrictions and interfere with endpoint protections.
Q: Why does BYOVD abuse increase ransomware impact so quickly?
A: BYOVD abuse moves the attacker into a privileged layer that can disable monitoring and accelerate encryption before defenders have a chance to intervene.
Q: What are the signs that Conti ransomware activity is progressing from initial access to impact?
A: The warning signs include suspicious authentication activity, brute-force attempts against RDP, unusual use of remote monitoring tools, malware staging on hosts, unexpected network scans of routers or storage devices, and abnormal outbound transfer activity.
Practitioner guidance
- Harden vulnerable-driver governance Inventory signed drivers that can be loaded on managed endpoints and block known vulnerable kernel drivers from execution paths wherever the platform supports it.
- Watch for kernel-level defense evasion Alert on sudden termination of AV and EDR processes, especially when it follows driver loading, IOCTL activity, or unusual device handle access.
- Correlate pre-encryption behaviours Tie together driver events, process enumeration, rapid file rename activity, and network-share enumeration so the first-stage symptoms are visible before mass encryption starts.
Bottom line: Reynolds ransomware demonstrates that a vulnerable signed driver can be enough to collapse endpoint defenses before encryption begins.
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09/07/2026 3:52 pm
BYOVD is a governance failure of trust in kernel provenance: organisations often treat a signed driver as a trusted runtime component, even when that driver can be weaponised. Reynolds shows that the trust decision cannot stop at signature validation if the binary can still be abused for privileged operations. The implication is that driver provenance and driver allowlisting are not niche hardening tasks but core endpoint governance requirements.
A question worth separating out:
Q: How should incident teams respond when ransomware kills AV or EDR processes?
A: Isolate the host immediately, preserve volatile evidence, and treat the endpoint as potentially untrustworthy at kernel level. The priority is containment and triage before the encryption routine finishes spreading to local and network storage.
👉 Read our full editorial: Reynolds ransomware shows how BYOVD breaks endpoint defenses