Every three years the Open Source Web Application Consortium releases its list of the top 10 web vulnerabilities. Year after year, top threats like SQL injection and Cross Site Scripting (XSS) battle for positioning as the worst of the worst, cementing themselves as perennial champions of the web vulnerability world. The 2013 OWASP Top 10 release candidate is out and available for comment now.

Since the list’s inception in 2004 much has changed online, and much has stayed the same. Many of the vulnerabilities from the original top ten have been on every list since or have been absorbed by broader categories. As with the list for 2010, the 2013 list is prioritized by risk. We've ordered this year's list along side the previous version for a comparison to show how risk has changed over the past three years, as well as how it has evolved.

An Error Has Occured
Error Message:

↑ ↓ movement up or down versus previous ranking
– no movement
↔ threat has been combined with or expanded upon another threat
† new to list (subpoint of threat, now its own threat)

2013 OWASP Top 10 Details

A1 - Injection

Injection flaws, such as SQL, OS, and LDAP injection occur when untrusted data is sent to an interpreter as part of a command or query. The attacker’s hostile data can trick the interpreter into executing unintended commands or accessing unauthorized data.


A2 - Broken Authentication and Session Management

Application functions related to authentication and session management are often not implemented correctly, allowing attackers to compromise passwords, keys, session tokens, or exploit other implementation flaws to assume other users’ identities.


A3 - Cross-Site Scripting

XSS flaws occur whenever an application takes untrusted data and sends it to a web browser without proper validation or escaping. XSS allows attackers to execute scripts in the victim’s browser which can hijack user sessions, deface web sites, or redirect the user to malicious sites.


A4 - Insecure Object Reference

A direct object reference occurs when a developer exposes a reference to an internal implementation object, such as a file, directory, or database key. Without an access control check or other protection, attackers can manipulate these references to access unauthorized data.


A5 - Security Misconfiguration

Good security requires having a secure configuration defined and deployed for the application, frameworks, application server, web server, database server, and platform. All these settings should be defined, implemented, and maintained as many are not shipped with secure defaults. This includes keeping all software up to date.


A6 - Security Misconfiguration

Many web applications do not properly protect sensitive data, such as credit cards, tax ids, and authentication credentials. Attackers may steal or modify such weakly protected data to conduct identity theft, credit card fraud, or other crimes. Sensitive data deserves extra protection such as encryption at rest or in transit, as well as special precautions when exchanged with the browser.


A7 - Missing Function Level Access Control

Virtually all web applications verify function level access rights before making that functionality visible in the UI. However, applications need to perform the same access control checks on the server when each function is accessed. If requests are not verified, attackers will be able to forge requests in order to access unauthorized functionality.


A8 - Cross-Site Request Forgery

A CSRF attack forces a logged-on victim’s browser to send a forged HTTP request, including the victim’s session cookie and any other automatically included authentication information, to a vulnerable web application. This allows the attacker to force the victim’s browser to generate requests the vulnerable application thinks are legitimate requests from the victim.


A9 - Using Components with Known Vulnerabilities

Vulnerable components, such as libraries, frameworks, and other software modules almost always run with full privilege. So, if exploited, they can cause serious data loss or server takeover. Applications using these vulnerable components may undermine their defenses and enable a range of possible attacks and impacts.


A10 - Unvalidated Redirects and Forwards

Web applications frequently redirect and forward users to other pages and websites, and use untrusted data to determine the destination pages. Without proper validation, attackers can redirect victims to phishing or malware sites, or use forwards to access unauthorized pages.

Web vulnerability breakdowns provided by OWASP. For Port80 Software's own breakdown of top web vulnerabilities, check out The Top 10 Most Dangerous Web Vulnerabilities

Port80's take on Web Vulnerabilities >>