"Ransomware gangs, especially those with ransomware-as-a-service (RaaS) programs, frequently produce new builds of their encryptors, and ensuring that each new build is reliably undetected can be time-consuming. More importantly, encryptors are inherently very noisy (as they inherently need to modify a large number of files in a short period); making such malware undetected is rather challenging."
"EDR killers act as a specialized, external component that's run to disable security controls before executing the lockers themselves, thereby keeping the latter simple, stable, and easy to rebuild. That's not to say there have not been instances where EDR termination and ransomware modules have been fused into one single binary."
"The goal of a BYOVD attack is to gain kernel-mode privileges, often called Ring 0. At this level, code has unrestricted access to system memory and hardware. Since an attacker cannot load an unsigned malicious driver, they 'bring' a driver signed by a reputable vendor (such as a hardware manufacturer or an old antivirus version) that has a known vulnerability."
EDR killer programs are commonly used in ransomware intrusions to neutralize security software before deploying file-encrypting malware. Ransomware gangs, particularly those operating RaaS programs, use EDR killers as specialized external components to disable security controls while keeping ransomware encryptors simple and stable. Analysis reveals that 54 of approximately 90 detected EDR killer tools leverage the BYOVD technique, exploiting 34 vulnerable drivers to gain kernel-mode privileges. This approach is preferred because it reliably achieves elevated access without requiring attackers to load unsigned malicious drivers, instead using legitimate but vulnerable drivers signed by reputable vendors.
Read at The Hacker News
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