Code Injection: What it is, how it leads to RCE, and how to prevent it

What it is

Code injection (often leading to remote code execution) is when attackers feed a program the kind of input it never expected—so it runs the attacker’s code instead of safe instructions. That “code” can be a script or DLL dropped after the first break-in. Our walkthrough

code injection guide

How it works

A vulnerable app trusts input (form fields, uploads, API calls).
The attacker crafts input that breaks out of normal handling.
Their code executes—downloading payloads, stealing data, or taking control.

What you might notice

Sudden processes you didn’t start; new services or tasks
Unusual outbound connections right after a form submit/upload
AV/EDR alerts about script hosts, PowerShell, or injected DLLs

If you suspect it

Isolate the host; preserve logs and memory.
Block the offending URL/IP at WAF/firewall.
Patch/disable the vulnerable feature; rotate secrets/keys.
Hunt laterally for dropped payloads and persistence.

Prevent it

Validate and sanitize all inputs; treat uploads as untrusted.
Use allow-lists (what’s allowed) rather than block-lists.
Turn on WAF/Runtime protections (e.g., RASP) and strict content security.
Keep apps, libraries, and frameworks updated; avoid risky plugins.
Run services with least privilege; restrict script interpreters.

Helpful?

Glossary (A-Z)

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