Shellcode Development (Windows/Linux/macOS)

Build shellcode as a constrained engineering problem: small PIC code, strict ABI behavior, reliable memory transitions, and reproducible test loops.

This skill is for implementation and validation workflow. It is not a vulnerability discovery skill.

When to activate

• Writing or reviewing shellcode/stagers in ASM/C/Python pipelines
• Building cross-platform syscall-based payloads (Windows/Linux/macOS)
• Porting payloads between x86_64 and arm64
• Handling bad-byte restrictions with encoder/decoder stages
• Implementing reflective/manual in-memory loading workflows
• Debugging crashes caused by calling-convention or stack-alignment mistakes
• Verifying payload behavior with emulator/disassembler tooling before runtime tests

If the task is specifically about BOFs, prefer bof/c-bof or bof/cpp-bof first. If it is specifically about stack masquerade or syscall gates, combine with offensive-coding/stack-spoofing or offensive-coding/indirect-syscall.