Research Lab

Apache Tomcat Remote Code Execution Vulnerability (CVE-2017-12617)

By Versa Staff

Versa Networks
October 18, 2017

Several Security Vulnerability have been patched in recently in Apache Tomcat. The list of fixed flaws recently addressed also included code execution vulnerabilities.
Apache Tomcat is the most widely used web application server, with over one million downloads per month and over 70% penetration in the enterprise datacenter.

The Apache Tomcat development team publicly disclosed the presence of a remote code execution vulnerability, tracked as CVE-2017-12617, affecting the popular web application server.

The Apache Tomcat versions 9.0.0.M1 to 9.0.0, 8.5.0 to 8.5.22, 8.0.0.RC1 to 8.0.46 and 7.0.0 to 7.0.81 are affected. The vulnerability is classified as “important” severity, has been fixed in latest version.

About CVE-2017-12617

The vulnerability only affected systems that have the HTTP PUT method enabled, it could be exploited by attackers to upload a malicious JSP file to target server using specially crafted request. Once file uploaded, the code it contains could be executed by requesting the file.

About Exploit

The Apache Tomcat team confirm that all above mentioned tomcat version are vulnerable for dangerous remote code execution (RCE) vulnerability on all operating system if default servlet or WebDAV servlet is enabled with the parameter readonly set to false.

<init-param>

        <param-name>readonly</param-name>

        <param-value>false</param-value>

     </init-param>

The Exploit available publically: https://github.com/cyberheartmi9/CVE-2017-12617/

This exploit is sending special crafted HTTP put request with JSP as payload to a Tomcat server. The code is executed when the uploaded JSP is accessed via a web browser (IE, Firefox and Chrome)

Mitigation

Update Tomcat to latest version where the vulnerability is fixed.
The readonly init-param should not be set to false.

Versa Security Solutions

Versa has released the following rules to address this vulnerability. However, more rules may be added or the current rules may change depending on the additional vulnerabilities information available.