By Derek Handova, Senior Technical Writer at Synopsys Software Integrity Group

An application security vulnerability is “a hole or a weakness in the application, which can be a design flaw or an implementation bug, that allows an attacker to cause harm to the stakeholders of an application,” according to OWASP. These stakeholders include the application owner, application users, and others that rely on the application.

While it doesn’t call them vulnerabilities on the top line, MITRE, which maintains the CWE list of common software security weaknesses, uses the term “vulnerability” in defining software weaknesses: “Software weaknesses are flaws, faults, bugs, vulnerabilities, and other errors in software implementation, code, design, or architecture that if left unaddressed could result in systems and networks being vulnerable to attack.”

These are certainly useful definitions to know. But they don’t add anything particularly actionable for software developers on their journey to secure coding. That’s where the security vulnerability lists like OWASP Top 10 Most Critical Web Application Security Risks and the similar but more extensive CWE/SANS Top 25 Most Dangerous Software Errors come into play.

These lists lay out the most critical types of security vulnerabilities to keep in mind as you develop software. But some application vulnerabilities warrant more scrutiny and mitigation efforts than others. So let’s take a closer look at the different types of vulnerabilities.

What are the different types of security vulnerabilities?

OWASP is well known for its top 10 list of web application security risks. But the organisation’s website also lists dozens of entries grouped into 20 types of security vulnerabilities. Categories include API AbuseInput Validation Vulnerability, and Session Management Vulnerability. OWASP’s application vulnerability descriptions talk about risk factors, give examples, and cross-link to related attacks, vulnerabilities, and controls.

MITRE and the SANS Institute put together the latest CWE/SANS Top 25 list in 2011. In that list, they categorise three main types of security vulnerabilities based their more extrinsic weaknesses:

  • Porous defences
  • Risky resource management
  • Insecure interaction between components

Porous defense vulnerabilities

Out of the CWE/SANS Top 25 types of security vulnerabilities, 11 involve porous defenses. Defensive techniques such as encryption, authentication, and authorisation, when implemented correctly, are essential to application security. But when they are misused, abused, or otherwise implemented incorrectly — or just ignored — they become application vulnerabilities.

Three of these vulnerabilities point to a basic lack of good housekeeping: Missing AuthenticationMissing Authorisation, and Missing Encryption. And three others have to do with erroneous or ill-advised use of application defense techniques, including Incorrect AuthorisationIncorrect Permission Assignment, and Improper Restriction of Excess Authentication Attempts.

Risky resource management vulnerabilities

Resource management involves creating, using, transferring, and destroying system resources such as memory. Proper, secure management resource is necessary for effective application defense. The types of security vulnerabilities in the CWE/SANS Top 25 category “Risky Resource Management” are related to ways that the software mismanages resources.

These application vulnerabilities range from the classic Buffer Overflow and Path Traversal to the more-sci-fi-sounding Inclusion of Functionality from Untrusted Control Sphere and the ominously named Use of Potentially Dangerous Function.

Defending against these application vulnerabilities boils down to two strategies:

  1. You must know what inputs you are using and whether they come from known “good” sources.
  2. You must use those inputs properly for their intended purposes.

Liberal use of sandboxing and whitelisting can help here, but there are no guarantees. Other options include application security testing and vulnerability assessments to uncover these eight types of security vulnerabilities before something goes wrong.

Vulnerabilities related to insecure interaction between components

The category “Insecure Interaction Between Components” has the fewest members of the CWE/SANS Top 25 software errors. But it also contains the most wanted—make that least wanted—list of security vulnerabilities. It’s a well-known rogues gallery bearing names like SQL InjectionCross-Site Scripting, and Open Redirect.

What do these types of security vulnerabilities all have in common? They’re all related to how “data is sent and received between separate components, modules, programs, processes, threads, or systems.”

For a more in-depth look at security vulnerabilities, check out Synopsys Software Integrity’s ebook: Anatomy of an Application Weakness, which takes you through the application vulnerability life cycle.


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