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Curriculum/Cybersecurity/Application Security/What is Application Security?
35 minBeginner

What is Application Security?

After this lesson, you will be able to: Explain why applications are a top attack target and where security fits in the software development lifecycle.

Web applications are the front door for most companies, and a goldmine for attackers. Application Security is the practice of building, testing, and operating software so an attacker can't trick it into doing the wrong thing.

Prerequisites:Intro to Cybersecurity

Why apps are the favorite target

Apps handle the data attackers want (credentials, payments, PII), they're internet-facing by design, and they're written by humans under deadline pressure. The Verizon DBIR consistently lists web app attacks as the #1 breach pattern. Even strong network security can't compensate for an SQL-injectable login page.

Security in the SDLC

Threat modeling at design time, what could go wrong? Secure coding guidelines during development. SAST (static analysis) and SCA (dependency scanning) on every commit. DAST scans against staging deployments. Pen tests before major releases. Bug bounty + monitoring in production. AppSec is woven through every step, not bolted on at the end.

Design
threat model
→
Code
SAST
→
Build
SCA
→
Deploy
DAST
→
Run
bug bounty
Shifting left: a security activity attached to every SDLC phase, not just a scan at the end.

💡 Shift left or pay 100x

A bug found in design costs $1 to fix. The same bug in production costs roughly $100. This is why modern AppSec invests heavily in earlier stages. IDE plugins, CI checks, threat modeling, even though it slows initial development.

OWASP, the AppSec community

The Open Worldwide Application Security Project (OWASP) is a free non-profit that publishes the most-referenced AppSec resources: the Top 10, the Web Security Testing Guide, the ASVS standard. Every AppSec engineer should bookmark owasp.org.

Quick Check

When is the cheapest time to fix an app vulnerability?

Choose the SDLC stage.

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