Cyber: Reynolds Ransomware Embeds Byovd Driver To Disable EDR Security Tools
Cybersecurity researchers have disclosed details of an emergent ransomware family dubbed Reynolds that comes embedded with a built-in bring your own vulnerable driver (BYOVD) component for defense evasion purposes within the ransomware payload itself.
BYOVD refers to an adversarial technique that abuses legitimate but flawed driver software to escalate privileges and disable Endpoint Detection and Response (EDR) solutions so that malicious activities go unnoticed. The strategy has been adopted by many ransomware groups over the years.
"Normally, the BYOVD defense evasion component of an attack would involve a distinct tool that would be deployed on the system prior to the ransomware payload in order to disable security software," the Symantec and Carbon Black Threat Hunter Team said in a report shared with The Hacker News. "However, in this attack, the vulnerable driver (an NsecSoft NSecKrnl driver) was bundled with the ransomware itself."
Broadcom's cybersecurity teams noted that this tactic of bundling a defense evasion component within the ransomware payload is not novel, and that it has been observed in a Ryuk ransomware attack in 2020 and in an incident involving a lesser-known ransomware family called Obscura in late August 2025.
In the Reynolds campaign, the ransomware is designed to drop a vulnerable NsecSoft NSecKrnl driver and terminate processes associated with various security programs from Avast, CrowdStrike Falcon, Palo Alto Networks Cortex XDR, Sophos (along with HitmanPro.Alert), and Symantec Endpoint Protection, among others.
It's worth noting that the NSecKrnl driver is susceptible to a known security flaw (CVE-2025-68947, CVSS score: 5.7) that could be exploited to terminate arbitrary processes. Notably, the driver has been put to use by a threat actor known as Silver Fox in attacks designed to kill endpoint security tools prior to delivering ValleyRAT.
Over the past year, the hacking group has previously wielded multiple legitimate but flawed drivers – including truesight.sys and amsdk.sys – as part of BYOVD attacks to disarm security programs.
By bringing together defense evasion and ransomware capabilities into one component, it makes it harder for defenders to stop the attack, not to mention obviating the need for an affiliate to separately incorporate this step into their modus operandi.
"Also of note in this attack campaign was the presence of a suspicious side-loaded loader on the target's network several weeks prior to th
Source: The Hacker News
