Cis Tomcat8 V100 10.20

10.20 Use the logEffectiveWebXml and metadata-complete settings for deploying applications in production (Scored)

Description

Both fragments and annotations give rise to security concerns. web.xml contains a metadata-complete attribute on the web-app element whose binary value defines whether other sources of metadata should be considered when deploying this web application, this includes annotations on class files (@WebServlet, but also @WebListener, @WebFilter, ...), web-fragment.xml as well as classes located in WEB-INF/classes. In addition, you can also allow you to log the effective web.xml, when an application starts, and the effective web.xml is the result of taking the main web.xml for your application merging in all the fragments applying all the annotations. By logging that, you are able to review it, and see if that is in fact what you actually want.

Rationale

Enable logEffectiveWebXml will allow you to log the effective web.xml and you are able to see if that is in fact what you actually want. Enable metadata-complete so that the web.xml is the only metadata considered.

Audit Procedure

1. Review each application's web.xml file located in the applications $CATALINA_HOME/webapps/<app_name>/WEB-INF/web.xml and determine if the metadata-complete is properly set.

<web-app
...
metadata-complete="true"
...
>

2. Review each application's context.xml file located in the applications $CATALINA_HOME/webapps/<app_name>/META-INF/context.xml and determine if the logEffectiveWebXml property is set.

<Context
...
logEffectiveWebXml="true"
...
>

Remediation

• Set the metadata-complete value in the web.xml in each of the applications to true.

Note: The metadata-complete option is not enough to disable all of annotation scanning. If there is a ServletContainerInitializer with a @HandlesTypes annotation, Tomcat has to scan your application for classes that use annotations or interfaces specified in that annotation.

• Set the logEffectiveWebXml value in the context.xml in each of the applications to true.

Default Value

If logEffectiveWebXml and/or metadata-complete is/are not specified, the default value is false.

References

1. https://tomcat.apache.org/tomcat-8.0-doc/config/context.html
2. https://alexismp.wordpress.com/2010/07/28/servlet-3-0-fragments-and-web-xml-to-rule-them-all/

CIS Controls

v7:

• 6.3 Enable Detailed Logging
  • Enable system logging to include detailed information such as an event source, date, user, timestamp, source addresses, destination addresses, and other useful elements.

Profile Applicability

• Level 1