Low-Level Exploitation: Kernel, Driver, and Firmware Attacks

Part of the Cybersecurity Skills Guide — This article is one deep-dive in our complete guide series.

By HADESS Team | February 28, 2026 | Updated: February 28, 2026 | 5 min read

Low-level exploitation targets the most privileged layers of the computing stack. Kernel exploits give you complete control of the operating system. Driver vulnerabilities provide a path from user space to kernel space. Firmware attacks persist below the OS entirely. This is the most technically demanding area of offensive security.

Kernel Exploits

Kernel vulnerabilities are high value because successful exploitation grants ring 0 privileges. Common vulnerability classes include:

Race conditions in kernel code are difficult to find and exploit but powerful. Time-of-check to time-of-use (TOCTOU) bugs in syscall handlers let you swap data between the kernel’s validation check and its use of that data. The Dirty COW vulnerability (CVE-2016-5195) exploited a race in the Linux memory management subsystem and affected virtually every Linux kernel for a decade.

Integer overflows in size calculations lead to undersized allocations followed by buffer overflows. When the kernel allocates a buffer based on a user-controlled size that wraps around to a small value, subsequent writes overflow the allocation.

Use-after-free in kernel objects follows the same pattern as userland UAF but with kernel heap structures. Techniques like heap spraying with sendmsg or msgsnd to control the contents of freed kernel allocations have been used in numerous Linux privilege escalation exploits.

Modern kernels have mitigations: KASLR randomizes kernel base address, SMEP prevents the kernel from executing userland pages, SMAP prevents kernel-mode access to userland memory, and CFI restricts control flow. Each mitigation narrows the exploitation path but does not eliminate it.

Driver Vulnerabilities

Third-party kernel drivers are a softer target than the core kernel. Drivers run with full kernel privileges but are often written with less security rigor. Common issues include:

IOCTL handlers that accept user-controlled data without proper validation. A driver that copies a user-supplied buffer into kernel memory based on a user-supplied length has a kernel buffer overflow. Windows drivers are particularly rich targets because any vendor can ship a signed driver that runs in the kernel.

Bring Your Own Vulnerable Driver (BYOVD) attacks use legitimately signed but vulnerable drivers to gain kernel access. Attackers install a known-vulnerable driver (which passes signature checks), exploit it to get kernel execution, and then use that access to disable security controls. This technique has been used by ransomware groups and APTs.

DMA attacks through external interfaces (Thunderbolt, PCIe) let hardware devices directly read and write system memory. Firmware implants on network cards or GPU firmware can maintain persistent kernel-level access that survives OS reinstallation.

Firmware Attacks

Firmware sits below the operating system and executes before the OS loads. UEFI firmware vulnerabilities can provide persistence that survives disk wipes and OS reinstalls.

UEFI implants modify the firmware to load malicious code during the boot process, before any OS security controls initialize. The LoJax implant (discovered by ESET in 2018) was the first UEFI rootkit found in the wild, attributed to APT28.

Secure Boot bypass attacks find ways to load unsigned code during the boot process. Vulnerabilities in boot loaders (like the BootHole vulnerability in GRUB2) or in the Secure Boot verification logic itself can undermine the entire trust chain.

BMC/IPMI attacks target the management controllers found in server hardware. These controllers have their own processors, memory, and network stack. Compromising a BMC gives you out-of-band access to the host, including virtual KVM access and the ability to modify firmware, regardless of the host OS state.

Practical Considerations

Low-level exploitation requires extensive lab work. Set up kernel debugging environments (QEMU with GDB for Linux, WinDbg with a kernel debugger for Windows). Practice with intentionally vulnerable drivers and CTF challenges before attempting real research.

Fuzzing is the primary bug-finding technique at this level. Tools like syzkaller (for Linux syscall fuzzing) and kAFL (for kernel code coverage-guided fuzzing) have found hundreds of kernel vulnerabilities.

Next Steps

• Assess your low-level security knowledge with the skills assessment
• Explore binary analysis and reverse engineering topics in the skills library
• Use the coaching tool to build a research-focused development plan

Related Guides in This Series

• Binary Exploitation: From Buffer Overflows to Modern Techniques — HADESS | 2026
• OWASP ZAP: Web Application Security Testing
• Penetration Testing Methodology: Scoping Through Reporting

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