DefaultServlet must be set to readonly for PUT and DELETE.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-222934	TCAT-AS-000090	SV-222934r615938_rule		Medium

Description
The DefaultServlet is a servlet provided with Tomcat. It is called when no other suitable page can be displayed to the client. The DefaultServlet serves static resources as well as directory listings and is declared globally in $CATALINA_BASE/conf/web.xml. By default, Tomcat behaves as if the DefaultServlet is set to "true" (HTTP commands like PUT and DELETE are rejected). However, the readonly parameter is not in the web.xml file by default so to ensure proper configuration and system operation, the "readonly" parameter in web.xml must be created and set to "true". Creating the setting in web.xml provides assurances the system is operating as required. Changing the readonly parameter to false could allow clients to delete or modify static resources on the server and upload new resources.

Description

The DefaultServlet is a servlet provided with Tomcat. It is called when no other suitable page can be displayed to the client. The DefaultServlet serves static resources as well as directory listings and is declared globally in $CATALINA_BASE/conf/web.xml. By default, Tomcat behaves as if the DefaultServlet is set to "true" (HTTP commands like PUT and DELETE are rejected). However, the readonly parameter is not in the web.xml file by default so to ensure proper configuration and system operation, the "readonly" parameter in web.xml must be created and set to "true". Creating the setting in web.xml provides assurances the system is operating as required. Changing the readonly parameter to false could allow clients to delete or modify static resources on the server and upload new resources.

STIG	Date
Apache Tomcat Application Sever 9 Security Technical Implementation Guide	2021-06-15

Details

Check Text ( C-24606r622485_chk )
From the Tomcat server run the following command: sudo cat $CATALINA_BASE/conf/web.xml \|grep -i -A5 -B2 defaultservlet If the "readonly" param-value for the "DefaultServlet" servlet class = "false" or does not exist, this is a finding.

Fix Text (F-24595r622486_fix)
From the Tomcat server console as a privileged user: Edit the $CATALINA_BASE/conf/web.xml file. If the "readonly" param-value does not exist, it must be created. Ensure the "readonly" param-value for the "DefaultServlet" servlet class = "true".