Linux Kernel Exploitation: A Hands-On Guide to Privilege Escalation

Linux kernel exploitation remains one of the most challenging and rewarding areas of cybersecurity research. This guide covers the essential theory and practical techniques needed to understand and exploit kernel vulnerabilities.

Key Topics Covered

• **Understanding kernel memory layout** and virtual address spaces in x86_64
• **Common vulnerability classes**: Use-After-Free, Heap Overflow, Race Conditions, and Double-Free
• **SMEP/SMAP/KPTI bypass techniques** in modern Linux kernels (5.x and 6.x)
• **Practical exploitation** with ret2dir and physmap sprays
• **Building a privilege escalation exploit chain** from CVE analysis to root shell
• **Kernel debugging** with QEMU + GDB and writing kernel fuzzers with syzkaller

Lab Setup

We'll set up a complete kernel exploitation environment using QEMU with a custom-compiled kernel, buildroot for a minimal filesystem, and GDB with the kgdb plugin for source-level kernel debugging.

Exploit Development Workflow

1. **Vulnerability Discovery**: Analyzing CVEs, patch diffing, and fuzzing with syzkaller
2. **Trigger Analysis**: Reproducing the crash and understanding the root cause
3. **Exploit Primitive**: Converting the bug into a read/write primitive
4. **Privilege Escalation**: Overwriting cred structures or modprobe_path
5. **Stabilization**: Post-exploitation cleanup to prevent kernel panic

⚠️ This content is for educational and defensive research purposes only.