Command Injection
Domain: Security
🎯 Motivation
Passing user input to shell commands lets attackers chain extra commands using ; or &&. Using safe APIs that avoid the shell entirely prevents this dangerous vulnerability.
📋 Concrete Example
Avoid os.system(f"convert {filename} out.png"). A filename like a.png; rm -rf / is catastrophic. Use subprocess.run(["convert", filename, "out.png"]) with a list — no shell, no injection.
🔗 Analogy
Giving a courier a sealed package with an address label is safe. If you hand them a note saying “deliver to A; also throw away everything at B,” you have given them two instructions.