Apache Struts 2.x <= 2.5.20 Multiple Vulnerabilities


The version of Apache Struts installed on the remote host is 2.x prior or equal to 2.5.20. It is, therefore, affected by multiple vulnerabilities: - The Apache Struts frameworks, when forced, performs double evaluation of attributes' values assigned to certain tags attributes such as id so it is possible to pass in a value that will be evaluated again when a tag's attributes will be rendered. With a carefully crafted request, this can lead to Remote Code Execution (RCE). The problem only applies when forcing OGNL evaluation inside a Struts tag attribute, when the expression to evaluate references raw, unvalidated input that an attacker is able to directly modify by crafting a corresponding request.Example:List available EmployeesIf an attacker is able to modify the skillName attribute in a request such that a raw OGNL expression gets passed to the skillName property without further validation, the provided OGNL expression contained in the skillName attribute gets evaluated when the tag is rendered as a result of the request.The opportunity for using double evaluation is by design in Struts since 2.0.0 and a useful tool when done right, which most notably means only referencing validated values in the given expression. However, when referencing unvalidated user input in the expression, malicious code can get injected. In an ongoing effort, the Struts framework includes mitigations for limiting the impact of injected expressions, but Struts before 2.5.22 left an attack vector open which is addressed by this report. This issue is similar to: S2-029 and S2-036. (CVE-2019-0230) - When a file upload is performed to an Action that exposes the file with a getter, an attacker may manipulate the request such that the working copy of the uploaded file is set to read-only. As a result, subsequent actions on the file will fail with an error. It might also be possible to set the Servlet container's temp directory to read only, such that subsequent upload actions will fail. In Struts prior to 2.5.22, stack-accessible values (e.g. Action properties) of type java.io.File and java.nio.File as well as other classes from these standard library packages are not properly protected by the framework to deny access to potentially harmful underlying properties. (CVE-2019-0233) Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.