There’s a concept in ransomware defense that has earned a mythic status over the past several years: encryption key capture. The idea is elegant. Ransomware encrypts your files using symmetric keys – AES, ChaCha20, Salsa20 – and those keys must exist in process memory, however briefly, before they’re wrapped with the attacker’s asymmetric public key and discarded. If you can grab the symmetric key material in that fleeting window, you can decrypt your own files without paying a ransom.
It’s a compelling recovery mechanism, and the concept has real academic pedigree. The lineage traces back to PayBreak in 2017, which was the first practical open-source implementation of real-time key material interception. Since then, multiple vendors and research teams have built commercial and open-source tools around the same principle, positioning key capture as the ultimate safety net: if everything else fails, at least you can still decrypt.
I still believe key capture has value as a forensic and recovery tool. But I’ve been watching the threat evolve over the past two years in ways that fundamentally undermine the assumptions key capture depends on, and I think it’s important to point out about where those cracks are forming before organizations anchor their ransomware strategies to a capability that may not be there when they need it most.
How Key Capture Works — And What It Assumes
To understand why key capture is losing ground, you have to understand the mechanics. Nearly all modern ransomware uses hybrid encryption: a symmetric cipher handles the heavy lifting of encrypting file contents at speed, while asymmetric encryption (typically RSA or ECC) protects the symmetric keys themselves. The symmetric key is generated on the victim’s machine, used to encrypt one or more files, and then encrypted with the attacker’s embedded public key. Once the symmetric key is wrapped or wiped from memory, it’s gone — unless you intercepted it first.
Key capture works by monitoring cryptographic API calls, hooking into the operating system’s memory management, or snapshotting process memory at the moment canary files detect encryption activity. The captured key material, session keys, initialization vectors, seed values, is stored securely so that a defender can later reverse the encryption without the attacker’s private key.
This methodology makes three critical assumptions. First, that the ransomware process is running locally on the endpoint where your agent is installed. Second, that your agent is still operational and hasn’t been disabled before encryption begins. And third, that there’s a meaningful and exploitable window between key generation and key destruction during which you can extract the material.
Every one of these assumptions is now under direct, sustained assault.
The most consequential shift in the ransomware landscape is one that many defenders still haven’t fully been able to adapt to: remote encryption. According to Malwarebytes’ 2026 State of Malware report, 86% of ransomware activity in 2025 involved remote encryption operations, attacks where the adversary encrypts data across the network from an unmanaged or compromised system, without ever running malicious code on the protected endpoint itself.
Think about what this means for key capture. Your agent is sitting on the target machine, waiting to intercept cryptographic activity in local process memory. But the encryption is happening on a different machine entirely, one that likely has no endpoint protection installed. The ransomware reads files over SMB, encrypts them in memory on the attacker-controlled node, and writes the ciphertext back. Your agent on the victim endpoint never sees a suspicious process. There’s no local key generation to intercept. The entire mechanism is bypassed without the attacker needing to do anything particularly clever. They just need access to one unmanaged system on the network.
This isn’t a theoretical edge case. It is now the dominant operational model for ransomware deployment. And it renders local key capture architecturally irrelevant for the majority of real-world attacks.
BYOVD: Killing the Agent Before It Can Act
Even when ransomware does execute locally, attackers have gotten remarkably good at neutralizing the security tools that would need to be running for key capture to work. Bring Your Own Vulnerable Driver (BYOVD) has become the most common defense evasion tactic used by ransomware operators in 2025 and into 2026.
The technique is straightforward and devastating: the attacker deploys a legitimately signed but vulnerable kernel-mode driver, exploits it to gain elevated privileges, and uses that access to terminate endpoint security processes, including EDR agents, antivirus, and any specialized ransomware protection tools that rely on userland or kernel hooks. Tools like TrueSightKiller, Poortry, GhostDriver, and AuKill have become standard components of the ransomware affiliate toolkit. The Reynolds ransomware family, documented just weeks ago by Broadcom researchers, took this a step further by embedding the BYOVD component directly into the ransomware payload itself, collapsing what used to be a multi-stage operation into a single, faster, harder-to-intercept execution.
If the agent responsible for key capture is terminated before encryption begins, there’s nothing to capture. It doesn’t matter how sophisticated your hooking mechanism is or how fast your memory snapshotting operates. A dead agent captures nothing.
Intermittent and Partial Encryption: Shrinking the Window to Nothing
Key capture’s viability has always depended on timing, on the existence of a window between key generation and key destruction where the material is accessible in memory. Ransomware developers have been systematically shrinking that window through intermittent and partial encryption techniques.
Research published by Index Engines [1] found that approximately 80% of ransomware variants analyzed in Q4 2025 employed intermittent, partial, or slow encryption methods, up 33% from Q2 of the same year. Families like BlackCat, LockBit, and Akira have pioneered approaches that encrypt only portions of each file, sometimes as little as every 16th byte. LockFile encrypts alternating 16-byte blocks specifically to avoid triggering the entropy-based detection mechanisms that many security tools, including canary-based key capture triggers, rely on.
These techniques create compounding problems. Per-file key lifetimes become shorter. Encryption I/O patterns fall below the anomaly thresholds that trigger memory snapshots. And in cases where the ransomware throttles its activity, what researchers describe as “slow-burn” encryption, the behavioral indicators that would initiate capture mechanisms may never fire at all. The ransomware encrypts your data quietly, over hours or days, and by the time anyone notices, the keys are long gone from memory.
Academic work on this is catching on. A 2025 paper on intermittent encryption measurement [2] noted that behavioral defenses struggle against slow-burn ransomware that throttles I/O below anomaly thresholds, requires privileged hooks that raise deployment barriers, and often detects only after partial data loss. That description applies equally well to key capture architectures, which face the same fundamental timing dependency.
Fileless Execution and Living Off the Land
Modern ransomware increasingly avoids dropping traditional executables to disk. Fileless techniques, executing entirely in memory, leveraging PowerShell, WMI, and other legitimate system tools, have become standard operating procedure. Industry data from 2025 confirms that living-off-the-land techniques now define the majority of modern ransomware campaigns, with attackers deliberately minimizing their digital footprint.
This creates a fundamental challenge for key capture architectures that rely on identifying and hooking into a distinct ransomware process. When the “ransomware” is a sequence of PowerShell commands encrypting files through native OS cryptographic APIs, the boundary between legitimate activity and malicious encryption becomes vanishingly thin. The encryption keys exist in the memory space of trusted system processes rather than in an identifiable malware binary, making targeted interception vastly more complex and prone to false positives.
AI-Driven Polymorphism: An Evolving Adversary
The final pressure on key capture comes from the accelerating sophistication of AI-enhanced ransomware development. Nearly 90% of ransomware samples analyzed in Q4 2025 exhibited polymorphic behaviors, code that mutates with every execution, making static analysis, signature-based identification, and machine learning algorithms functionally useless.
ESET documented PromptLock in 2025 [3], the first known AI-powered ransomware, which used large language models to dynamically generate and modify its code. While PromptLock was likely a proof of concept, the trajectory it represents is clear: AI enables attackers to generate novel encryption routines, customize obfuscation per-target, and potentially alter the cryptographic implementation itself in ways that defeat hardcoded interception logic. If the key generation pathway changes with every deployment, the hooks and patterns that key capture agents depend on become unreliable.
SentinelOne researchers separately identified MalTerminal [4], a GPT-4-powered malware capable of generating ransomware code at runtime. When the code that generates and manages encryption keys is itself being written on the fly by a language model, the assumptions underpinning key capture aren’t just strained. They’re structurally unsound.
I should note that there’s healthy skepticism about how much of the AI-polymorphism threat is real today versus vendor-driven hype.
Security researcher Marcus Hutchins has rightly pointed out that current AI-generated mutation engines don’t yet offer clear advantages over traditional obfuscation techniques. That’s a fair assessment of where we are in early 2026. But the trajectory matters more than the current snapshot. The tooling is improving rapidly, and the barrier to building AI-assisted ransomware is falling just as fast. Defenders who dismiss the trajectory because today’s examples are crude will find themselves unprepared when the examples stop being crude.
The Uncomfortable Math
Let me put this plainly. Key capture requires four conditions to function: (1) a functioning agent on the endpoint where encryption occurs, (2) local execution of the ransomware process, (3) an exploitable time window for key extraction, and (4) predictable cryptographic implementation patterns to target.
Remote encryption eliminates condition two for the vast majority of attacks. BYOVD eliminates condition one. Intermittent encryption degrades condition three. And AI-driven polymorphism undermines condition four.
That doesn’t mean key capture is worthless. In the subset of cases where ransomware executes locally on a protected endpoint, using conventional cryptographic libraries, without first disabling the agent, and with sufficient dwell time for memory extraction, key capture can still provide a viable recovery path. That’s a real and valuable capability. Every additional chance at recovery matters when you’re staring down a ransom note.
But positioning key capture as the anti-ransomware strategy, as the primary thing standing between an organization and a ransom payment, is a bet with worse odds every quarter. The conditions it requires are being systematically dismantled by the very adversaries it’s supposed to defeat.
What This Tells Us About Where Defense Is Heading
The broader lesson here isn’t really about key capture specifically. It’s about the limits of any defense model that depends on reacting to encryption after it starts. Whether you’re capturing keys, rolling back from snapshots, or restoring from backups, you are operating downstream of the damage event. You’re accepting that the attacker has already achieved their objective and trying to undo the consequences.
That made sense in a world where ransomware moved at human speed, used predictable tooling, and executed on managed endpoints in visible processes. None of those conditions reliably hold anymore.
The organizations I’m watching most closely right now are the ones shifting their defensive center of gravity upstream, from recovery after encryption to denial of the conditions encryption requires. That looks like approaches that make the attack surface unpredictable, that conceal critical data before an attacker can target it, that detect adversary presence during reconnaissance rather than during payload execution, and that operate independently of any single agent’s survival.
To be clear, none of this means key capture should be shelved, just like nobody should be ripping out EDR or backups. Defense in depth remains the right architectural principle, and key capture is a valid recovery layer for the scenarios where it can still function.
But treating key capture, or any single recovery mechanism, as synonymous with ransomware resilience is a bet against the trendline. The center of gravity is shifting, whether we push it or not. From intercepting keys to ensuring there is nothing for those keys to lock. From outrunning the attack to making the attack irrelevant.
The attackers have already moved in that direction. I think the defenders who see it early will be glad they did.
Brad Potteiger is the Chief Technology Officer at Arms Cyber, where he leads the development of next-generation preemptive security & anti-ransomware technology. Arms Cyber’s patented Stealth Posture Management platform protects organizations across Windows, Linux, and MacOS by making critical data invisible and resilient to attackers.
References
[1] Index Engines, “New Research from Index Engines Shows Ransomware Continues Shift Towards Polymorphism, Shadow Encryption, and Wiper-Style Attacks,” PR Newswire, February 24, 2026. https://www.prnewswire.com/news-releases/new-research-from-index-engines-shows-ransomware-continues-shift-towards-polymorphism-shadow-encryption-and-wiper-style-attacks-302694885.html
[2] Y. Ineza, G. Jackson, P. Niyonkuru, J. Kevil, and A. Serwadda, “Intermittent File Encryption in Ransomware: Measurement, Modeling, and Detection,” arXiv:2510.15133, October 2025. https://arxiv.org/abs/2510.15133
[3] ESET Research, “First known AI-powered ransomware uncovered by ESET Research,” WeLiveSecurity, August 27, 2025. https://www.welivesecurity.com/en/ransomware/first-known-ai-powered-ransomware-uncovered-eset-research/
[4] A. Delamotte, V. Kamluk, and G. Bernadett-Shapiro, “Researchers expose MalTerminal, an LLM-enabled malware pioneer,” SentinelOne SentinelLABS, presented at LABScon 2025, September 2025. https://securityaffairs.com/182433/malware/researchers-expose-malterminal-an-llm-enabled-malware-pioneer.html
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