CVE-2016-1182: Improper Input Validation in Apache Struts

Background

Apache Struts is an open-source framework for developing Java web applications. It provides a set of reusable components and a MVC (Model-View-Controller) architecture for building scalable and maintainable web applications. The vulnerability identified as CVE-2016-1182 affects Apache Struts versions 1.x through 1.3.10. This vulnerability arises due to improper input validation in the ActionServlet.java file, which fails to properly restrict the Validator configuration. As a result, remote attackers can exploit this vulnerability to conduct cross-site scripting (XSS) attacks or cause a denial of service by submitting crafted input. This vulnerability is similar to CVE-2015-0899.

Vulnerability Detail

The vulnerability in Apache Struts allows remote attackers to exploit the application by submitting malicious input. This can lead to cross-site scripting (XSS) attacks, where the attacker injects malicious scripts into web pages viewed by other users. Additionally, the vulnerability can be used to cause a denial of service, potentially disrupting the availability of the affected application. The vulnerability is rated as HIGH severity with a CVSS score of 8.2. It is classified under CWE-20, which refers to improper input validation.

Workaround

If upgrading to a non-affected version of Apache Struts is not immediately feasible, a possible workaround is to implement custom input validation and output encoding mechanisms to mitigate the risk of XSS attacks. This can involve validating and sanitizing user input before using it in dynamic web content and applying appropriate encoding techniques to prevent script injection. Here is an example of how input validation and output encoding can be implemented in Java:

// Input validation

String userInput =

request.getParameter("input");

if (userInput != null) {
  // Sanitize input

String sanitizedInput = userInput.replaceAll("<", "<").replaceAll(">", ">");

  // Use sanitized input in dynamic content
  response.getWriter().println("Hello " + sanitizedInput);
}

// Output encoding

String userContent = "<script>

alert('XSS');

</script>"; String encodedContent =

ESAPI.encoder().encodeForHTML(userContent);

response.getWriter().println(encodedContent);

Conclusion

The vulnerability in Apache Struts, identified as CVE-2016-1182, allows remote attackers to conduct cross-site scripting attacks or cause a denial of service. It is important to upgrade to a non-affected version of Apache Struts and follow proper input validation and output encoding practices to mitigate the risk. For further support on vulnerability remediation, please contact DevNack.com.

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