PHASE 1 — FOUNDATION (RCE)

Basically before now I approached RCE as a vuln instead of an end result, for me it was just LFI and SSRF but now I’m on my journey to master RCE perfectly , so yh this is my learning material

Let’s strip it down so bare that even a baby-level mental model can grasp it. Before we even touch “remote code execution,” we need to break down two pieces separately: execution and remote.

1. What is “execution” in computing?

Execution simply means a computer running instructions. A processor (CPU) doesn’t understand English or JavaScript—it understands machine code: a sequence of binary instructions (like 10110000). When we say “program executes,” it means the CPU is reading instructions from memory, interpreting them step by step, and carrying them out (like adding numbers, moving data, branching to another part of the program).

To make life easier, we humans write in higher-level languages (Python, C, Java). These are either:

• Compiled → turned into machine code before running (e.g., C → binary).
• Interpreted → read line by line and executed by another program (e.g., Python interpreter).
• Bytecode + VM → compiled into a middle form, then run inside a controlled environment (Java → JVM, C# → CLR).

But the end result is the same: instructions execute.

So “execution” = telling the CPU (or a virtual CPU, like JVM) to carry out instructions.

2. What does “code” mean here?

“Code” = instructions. That might be:

• Native machine instructions (like mov eax, ebx).
• Script instructions (Python, PHP, JavaScript).
• SQL statements interpreted by a database engine.
• Shell commands interpreted by /bin/sh.

Every system has its own execution environment: web server executes PHP, browser executes JavaScript, DB engine executes SQL, OS shell executes Bash.