How VEN0m Ransomware Uses Vulnerable Drivers to Bypass Modern Security: A Technical Breakdown
Hook
Most ransomware tries to kill security processes in memory—but what if you could just delete the antivirus software from disk before it even knows you’re there? VEN0m does exactly that, and it’s fully undetectable against major AV vendors.
Context
Modern endpoint security has become increasingly sophisticated, with kernel-mode drivers, protected processes, and behavior-based detection making traditional malware techniques obsolete. EDR solutions run with SYSTEM privileges, hook kernel APIs, and are specifically designed to resist termination attempts. Security vendors have largely won the arms race against simple process killers and in-memory tampering.
But there’s a fundamental asymmetry in endpoint security: while these products are excellent at protecting themselves in memory, they’re surprisingly vulnerable to disk-level attacks. VEN0m exploits this blind spot using a BYOVD (Bring Your Own Vulnerable Driver) technique—bundling a legitimate, Microsoft-signed driver from IObit Malware Fighter that contains a critical vulnerability (CVE-2025-26125). By loading this trusted driver into the kernel, VEN0m gains the ability to perform arbitrary file deletion with kernel privileges, targeting the installation directories of security products before they can respond. Written in Rust for memory safety and cross-compilation capabilities, VEN0m represents a new generation of ransomware that combines old-school privilege escalation with modern evasion tactics.
Technical Insight
VEN0m’s architecture is a masterclass in Windows exploitation, orchestrating five distinct attack stages into a cohesive ransomware operation. The attack begins with a UAC bypass using the Slui.exe hijacking technique—exploiting Windows’ Software Licensing executable to spawn elevated processes without triggering User Account Control prompts. This works by creating a registry key at HKCU\Software\Classes\exefile\shell\open\command that the elevated Slui.exe process reads, allowing arbitrary code execution with high integrity.
The core innovation is the BYOVD implementation using IObit’s IMFForceDelete.sys driver. Rather than attempting to terminate security processes—which modern EDR solutions defend against aggressively—VEN0m loads this vulnerable signed driver and uses it to recursively delete entire AV/EDR installation directories from disk. The Rust implementation leverages the windows-sys crate to interact with the Service Control Manager:
use windows_sys::Win32::System::Services::*;
use std::ffi::OsStr;
use std::os::windows::ffi::OsStrExt;
fn load_vulnerable_driver(driver_path: &str) -> Result<(), Box<dyn std::error::Error>> {
let sc_manager = unsafe {
OpenSCManagerW(std::ptr::null(), std::ptr::null(), SC_MANAGER_ALL_ACCESS)
};
let service_name: Vec<u16> = OsStr::new("IMFForceDelete")
.encode_wide().chain(Some(0)).collect();
let driver_path_wide: Vec<u16> = OsStr::new(driver_path)
.encode_wide().chain(Some(0)).collect();
let service = unsafe {
CreateServiceW(
sc_manager,
service_name.as_ptr(),
service_name.as_ptr(),
SERVICE_ALL_ACCESS,
SERVICE_KERNEL_DRIVER,
SERVICE_DEMAND_START,
SERVICE_ERROR_IGNORE,
driver_path_wide.as_ptr(),
std::ptr::null(),
std::ptr::null_mut(),
std::ptr::null(),
std::ptr::null(),
std::ptr::null(),
)
};
unsafe { StartServiceW(service, 0, std::ptr::null()) };
Ok(())
}Once the driver is loaded, VEN0m communicates with it via DeviceIoControl calls to perform kernel-mode file deletion operations that bypass all usermode security hooks. The tool targets specific directories hardcoded in the binary—installation paths for major AV vendors including Kaspersky, Norton, Bitdefender, Windows Defender, CrowdStrike, and others. By deleting these folders at the file system level with kernel privileges, VEN0m effectively blinds the system before encryption begins.
The encryption phase uses a straightforward symmetric key approach with a 32-byte key hardcoded at compile time. The Rust implementation likely uses the aes crate for AES-256 encryption, iterating through specified drive letters and file extensions. VEN0m’s configuration allows customization of target extensions (documents, images, databases) and exclusion patterns to avoid encrypting system-critical files that would prevent ransom payment.
Persistence is established through Winlogon registry hijacking, modifying the HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit key to execute VEN0m’s payload on every user login. The ransom note is deployed via a scheduled task that displays a GUI window with payment instructions. Notably, VEN0m includes a companion “Antid0te” decryptor compiled with the matching hardcoded key, demonstrating the complete attack lifecycle in a proof-of-concept context.
The modular architecture uses Cargo’s conditional compilation features, allowing different components to be built independently. The repository structure separates the main ransomware logic, the decryptor, and the ransom note GUI into distinct binaries, each with their own feature flags. This modularity makes the codebase easier to study and modify for red team operations, though it also reveals the educational rather than operational intent.
Gotcha
The most significant limitation is one the author openly documents: the UAC bypass fails against systems running Microsoft Defender, which is enabled by default on all modern Windows installations. This single point of failure means VEN0m is immediately ineffective on unmodified Windows 10/11 systems—precisely the most common deployment scenario. For a ransomware claiming to be “fully undetectable,” failing against the default security posture is a critical weakness that severely limits practical deployment.
The hardcoded encryption key is the project’s Achilles heel. Unlike real-world ransomware that generates unique keys per victim and exfiltrates them to command-and-control servers, VEN0m compiles the key directly into the binary. Any incident responder who retrieves the executable can immediately extract the key and decrypt all affected files without paying the ransom. While this design choice makes sense for a proof-of-concept educational tool, it completely undermines the threat model of actual ransomware operations. Additionally, the BYOVD technique has a short shelf life—Microsoft’s driver blocklist is constantly updated, and once IMFForceDelete.sys from IObit Malware Fighter v12.1.0 is added, the tool becomes non-functional. The author even acknowledges that the specific CVE-2025-26125 vulnerability will eventually be patched and blocked, requiring constant driver hunting and integration work to maintain effectiveness.
Verdict
Use if: You’re a security researcher studying modern ransomware techniques, conducting authorized red team engagements in controlled environments, or teaching offensive security concepts. VEN0m’s BYOVD implementation provides an excellent case study in Windows driver exploitation, and the Rust codebase is clean and well-structured for educational purposes. The modular architecture makes it easy to extract individual techniques (UAC bypass, registry persistence, driver loading) for incorporation into other security testing tools. If you’re building detection signatures or defensive capabilities against BYOVD attacks, analyzing VEN0m’s approach to disk-based AV evasion offers valuable threat intelligence.
Skip if: You need a production-ready security testing framework, require operational security for real engagements, or expect the tool to work beyond its limited window of effectiveness. The hardcoded encryption key, reliance on a specific soon-to-be-blocklisted driver, and failure against default Windows Defender configurations make this impractical for serious red team operations. The repository’s high visibility (163 stars) also means detection signatures are likely already developed by major AV vendors. For practical ransomware simulation in enterprise environments, commercial tools like Caldera or Atomic Red Team provide better coverage, documentation, and legal protection. VEN0m is fundamentally a proof-of-concept that demonstrates “what’s possible” rather than a maintained offensive tool—valuable for learning, risky for deployment.
