What Is Application Security?

Application security is the practice of protecting software applications from attack across their whole life, covering the code that builds them, the components they pull in, the configuration they ship with, and the behavior of the systems running them in production.

Practitioners shorten the term to AppSec, and the boundary that matters most is the layer at which each discipline operates. Network and infrastructure security defend the environment an application sits in, controlling who reaches the host and what the host can reach. The logic inside that environment is what this discipline defends, which is why an application with correct firewall rules, patched hosts, and encrypted traffic can still hand an attacker another customer's records through a request that every network control considers legitimate.

Which Risks AppSec Addresses

OWASP maintains the reference list for web applications, and the Top 10:2025 is its current edition, the first revision since 2021. Each of its ten categories groups a set of weakness classes, averaging 25 per category and running from 5 in the smallest to a deliberate cap of 40 in the largest, drawn from contributed testing data and a practitioner survey.

Broken access control holds first place, as it has since 2021, appearing in 3.73% of applications tested and now absorbing server-side request forgery, which was its own category in the previous edition. Security misconfiguration climbed from fifth to second. Software supply chain failures entered at third, replacing the narrower category for vulnerable and outdated components, and mishandling of exceptional conditions arrived as a new tenth.

Injection, cryptographic failures and insecure design each dropped two places in the same revision, which is the clearest signal in the document that a decade of secure coding work has moved the needle on the defect classes teams control directly. The specific defect types underneath these headings are covered in this guide to application security vulnerabilities.

The Top 10 is widely misread as a checklist. OWASP describes it as an awareness document, and the organization publishes a separate standard for the work of verification. The Application Security Verification Standard, first released in 2008 and now at version 5.0 as of May 2025, turns those risk categories into testable requirements sorted into levels, so a team picks a level to match the assurance an application needs rather than working through a list of headings. A program citing the Top 10 as its standard has chosen the awareness document over the standard.

Where the Controls Sit

Tooling divides by the moment it operates, and the moment determines what it can see.

Each stage sees something the others cannot, since build-time controls read every path through the code while knowing nothing about which ones execute. Runtime controls know exactly which executed and nothing about the paths never taken. Programs that rely on one stage inherit that stage's blind spot as a permanent condition.

Shift Left, and What It Leaves Behind

The dominant strategy for a decade has been to move security work earlier, catching defects in development where they cost least to fix. It works, and it is incomplete for reasons visible in the OWASP list itself.

Misconfiguration is decided at deployment, and supply chain failures arrive through components a developer never wrote and often never chose. Credential abuse and the misuse of features working exactly as designed involve no defect to catch at all. None of these has a left to shift to.

That gap is the argument for runtime application security, which observes the application in the environment it runs in rather than the one it was tested in.

Application Security Best Practices

1. Know what you have before securing it. An inventory of applications, their owners, their internet exposure, and the data they touch decides where everything else goes, and a program without one protects whichever subset happened to get registered.
   
   
2. Assign every application a named owner. Findings routed to a team rather than a person age indefinitely.
   
   
3. Rank and schedule by exploitability, not severity alone. A critical rating on a component that never loads should not sit above a moderate one on a reachable path, and an internet-facing exploitable flaw should not share a deadline with an internal unreachable one.
   
   
4. Measure coverage rather than volume. The number of findings says more about scanner configuration than about risk, while the proportion of applications under any testing at all says something real.
   
   
5. Protect what cannot be fixed yet. Third-party software, systems awaiting a vendor patch, and code nobody owns still run, and runtime controls are what stand between them and an attacker while the queue clears.

Who Owns the Work

Ownership is shared in a way that generates friction. Development writes the code and carries the remediation work, while security defines requirements, runs the tooling, and interprets what comes out. Deployment and the runtime environment belong to operations, and the deadlines usually arrive from compliance, outside all three.

Programs fail at the seams between these groups more often than at any technical control. Findings that arrive without context get ignored, deadlines set without engineering input get missed, and runtime protection deployed without developer awareness gets disabled during the first incident it causes.

Raven works at the stage where the evidence is strongest, analyzing how code behaves inside the running application and stopping malicious execution as it happens, including against defects no scan flagged and no patch yet exists for. Book a demo to watch it run against your own applications.