Free preview lesson · Application Security & Secure Coding · Module 1: Thinking like an attacker
Why applications get breached
Secure code starts with understanding how applications actually get breached. Most attacks exploit a small number of recurring mistakes.
Untrusted input
Anything from outside your code — form fields, URLs, headers, files, API payloads — can be crafted by an attacker. Injection and cross-site scripting both happen when untrusted input is treated as code or markup.
Broken access control
Applications often check that a user is logged in but forget to check that they are allowed to see a particular record. Changing an ID in a URL to view someone else's data is one of the most common real-world flaws.
Vulnerable dependencies and configuration
Modern applications rely on many third-party packages, and outdated ones may contain known vulnerabilities. Default credentials, verbose error messages and missing security headers add further easy openings.
Common pitfall
Relying on client-side validation for security. Anything in the browser can be bypassed; checks must also happen on the server.
Action step
Pick one endpoint in code you work on and list every input it accepts and where each one is validated.
This is one lesson from Application Security & Secure Coding.
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