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Introduction OWASP Top Ten 2004 Project

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The Open Web Application Security Project (OWASP) is dedicated to helping organizations understand and improve the security of their web applications and web services. This list was created to focus corporations and government agencies on the most serious of these vulnerabilities. Web application security has become a hot topic as companies race to make content and services accessible though the web. At the same time, hackers are turning their attention to the common weaknesses created by application developers.

When an organization puts up a web application, they invite the world to send them HTTP requests. Attacks buried in these requests sail past firewalls, filters, platform hardening, and intrusion detection systems without notice because they are inside legal HTTP requests. Even “secure” websites that use SSL just accept the requests that arrive through the encrypted tunnel without scrutiny. This means that your web application code is part of your security perimeter. As the number, size and complexity of your web applications increases, so does your perimeter exposure.

The security issues raised here are not new. In fact, some have been well understood for decades. Yet for a variety of reasons, major software development projects are still making these mistakes and jeopardizing not only their customers’ security, but also the security of the entire Internet. There is no “silver bullet” to cure these problems. Today’s assessment and protection technology is improving, but can currently only deal with a limited sub-set of the issues at best. To address the issues described in this document, organizations will need to change their development culture, train developers, update their software development processes, and use technology where appropriate.

The OWASP Top Ten is a list of vulnerabilities that require immediate remediation. Existing code should be checked for these vulnerabilities immediately, as these flaws are being actively targeted by attackers. Development projects should address these vulnerabilities in their requirements documents and design, build, and test their applications to ensure that they have not been introduced. Project managers should include time and budget for application security activities including developer training, application security policy development, security mechanism design and development, penetration testing, and security code review.

We encourage organizations to join the growing list of companies that have adopted the OWASP Top Ten as a minimum standard and are committed to producing web applications that do not contain these vulnerabilities.

We have chosen to present this list in a format similar to the highly successful SANS/FBI Top Twenty List in order to facilitate its use and understanding. The SANS list is focused on flaws in particular widely used network and infrastructure products. Because each website is unique, the OWASP Top Ten is organized around particular types or categories of vulnerabilities that frequently occur in web applications. These categories are being standardized in the OASIS Web Application Security (WAS) XML Project.

This list represents the combined wisdom of OWASP experts, whose experience includes many years of application security work for governments, financial services, pharmaceuticals and manufacturing, as well as developing tools and technology. This document is designed to introduce the most serious web application vulnerabilities. There are many books and guidelines that describe these vulnerabilities in more detail and provide detailed guidance on how to eliminate them. One such guideline is the OWASP Guide available at

The OWASP Top Ten is a living document. It includes instructions and pointers to additional information useful for correcting these types of security flaws. We update the list and the instructions as more critical threats and more current or convenient methods are identified, and we welcome your input along the way. This is a community consensus document – your experience in fighting attackers and in eliminating these vulnerabilities can help others who come after you. Please send suggestions via e-mail to [email protected] with the subject "OWASP Top Ten Comments.”