CVE-2017-5664 in Interactive Session Recorder
Summary
by MITRE
The error page mechanism of the Java Servlet Specification requires that, when an error occurs and an error page is configured for the error that occurred, the original request and response are forwarded to the error page. This means that the request is presented to the error page with the original HTTP method. If the error page is a static file, expected behaviour is to serve content of the file as if processing a GET request, regardless of the actual HTTP method. The Default Servlet in Apache Tomcat 9.0.0.M1 to 9.0.0.M20, 8.5.0 to 8.5.14, 8.0.0.RC1 to 8.0.43 and 7.0.0 to 7.0.77 did not do this. Depending on the original request this could lead to unexpected and undesirable results for static error pages including, if the DefaultServlet is configured to permit writes, the replacement or removal of the custom error page. Notes for other user provided error pages: (1) Unless explicitly coded otherwise, JSPs ignore the HTTP method. JSPs used as error pages must must ensure that they handle any error dispatch as a GET request, regardless of the actual method. (2) By default, the response generated by a Servlet does depend on the HTTP method. Custom Servlets used as error pages must ensure that they handle any error dispatch as a GET request, regardless of the actual method.
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Analysis
by VulDB Data Team • 08/23/2024
The vulnerability described in CVE-2017-5664 represents a critical flaw in the Java Servlet specification implementation within Apache Tomcat versions ranging from 7.0.0 through 7.0.77, 8.0.0.RC1 through 8.0.43, 8.5.0 through 8.5.14, and 9.0.0.M1 through 9.0.0.M20. This issue stems from the improper handling of error page mechanisms where the servlet container fails to correctly normalize the HTTP method when forwarding requests to error pages. The vulnerability specifically affects the Default Servlet implementation which is responsible for serving static content, creating a scenario where the original HTTP method is preserved during error dispatch operations. According to the servlet specification, when an error occurs and an error page is configured, the original request and response should be forwarded to the error page while maintaining proper method handling. However, Tomcat's Default Servlet implementation did not adhere to this requirement, leading to potential security implications when static error pages were involved.
The technical flaw manifests when an application experiences an error condition and an error page is configured to handle that specific error type. During the error dispatch process, the servlet container forwards the original request to the configured error page while preserving the original HTTP method that triggered the error. This behavior becomes problematic when the error page is a static file because the Default Servlet should normalize all error page requests to GET method regardless of the original request method. When the Default Servlet is configured with write permissions, this vulnerability can be exploited to modify or remove custom error pages, potentially allowing attackers to replace them with malicious content or completely eliminate them from the application's error handling mechanism. The vulnerability essentially creates a path where an attacker can leverage the preserved HTTP method to perform unintended operations against static error page resources, particularly when write access is permitted.
The operational impact of CVE-2017-5664 extends beyond simple functionality degradation to potential security compromise within web applications hosted on affected Tomcat versions. Attackers can exploit this vulnerability by crafting specific requests that trigger error conditions, then manipulating the HTTP method to gain unauthorized access to static error page resources. When the Default Servlet is configured with write capabilities, the vulnerability enables modification or deletion of custom error pages, which can have cascading effects on application security posture. The implications are particularly severe in environments where error pages contain sensitive information or serve as part of the application's security framework. This vulnerability aligns with CWE-20: Improper Input Validation and can be mapped to ATT&CK technique T1059.007 for web shell deployment through error page manipulation. The vulnerability also relates to CWE-310: Cryptographic Issues when considering the potential for information disclosure through manipulated error handling mechanisms, and CWE-79: Cross-site Scripting when error pages contain user-controllable content.
Organizations affected by this vulnerability should implement immediate mitigations including upgrading to patched versions of Apache Tomcat where the issue has been resolved. The recommended approach involves updating to versions that properly implement the servlet specification requirements for error page handling, ensuring that the Default Servlet correctly normalizes HTTP methods during error dispatch operations. Administrators should also review their error page configurations to minimize write permissions on static error resources and ensure that custom error pages are properly secured. Additionally, implementing proper access controls and monitoring for unauthorized modifications to error page resources can help detect exploitation attempts. Security teams should conduct thorough assessments of their Tomcat installations to identify all affected versions and ensure that the Default Servlet is not configured with unnecessary write permissions to static resources. The vulnerability demonstrates the critical importance of proper servlet specification compliance in web application containers and highlights the potential for seemingly benign configuration issues to create significant security risks when combined with improper input handling and access control mechanisms.