Shellcode and Exploitation

Shellcode is a small piece of machine code that performs an action when executed, classically spawning a shell. It is the payload you redirect execution to after controlling EIP.

It is written in raw bytes (opcodes) so it can be injected directly into memory.

Common payload goals include:

• Bind shell: opens a listening port on the victim.
• Reverse shell: connects back to the attacker (better through firewalls/NAT).
• Execute command: runs a single command like adding a user.

Reverse shells are most common in real engagements.