Summary
A possible Remote Code Execution attack when using an expression in Freemarker tag instead of string literalsWho should read this | All Struts 2 developers and users |
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Impact of vulnerability | A RCE attack is possible when developer is using wrong construction in Freemarker tags |
Maximum security rating | Critical |
Recommendation | Upgrade to Struts 2.5.12 or Struts 2.3.34 |
Affected Software | Struts 2.1.2 - Struts 2.3.33, Struts 2.5 - Struts 2.5.10 |
Reporter | Lupin <lupin1314 at gmail dot com> - jd.com security team |
CVE Identifier |
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Problem
The REST Plugin is using a XStreamHandler
with an instance of XStream for deserialization without any type filtering and this can lead to Remote Code Execution when deserializing XML payloads.
Solution
Upgrade to Apache Struts version 2.5.13 or 2.3.34.
Backward compatibility
It is possible that some REST actions stop working because of applied default restrictions on available classes. In such case please investigate the new interfaces that was introduced to allow define class restrictions per action, those interfaces are:
org.apache.struts2.rest.handler.AllowedClasses
org.apache.struts2.rest.handler.AllowedClassNames
org.apache.struts2.rest.handler.XStreamPermissionProvider
Workaround
The best option is to remove the Struts REST plugin when not used. Alternatively you can only upgrade the plugin by dropping in all the required JARs (plugin plus all dependencies). Another options is to limit th plugin to server normal pages and JSONs only:
<constant name="struts.action.extension" value="xhtml,,json" />