Summary
Improves excluded params in ParametersInterceptor and CookieInterceptor to avoid ClassLoader manipulationWho should read this | All Struts 2 developers and users |
---|---|
Impact of vulnerability | ClassLoader manipulation |
Maximum security rating | High |
Recommendation | Developers should immediately upgrade to Struts 2.3.16.2 |
Affected Software | Struts 2.0.0 - Struts 2.3.16.1 |
Reporter | Taki Uchiyama (JPCERT/CC), Takeshi Terada (Mitsui Bussan Secure Directions, Inc.), Takayoshi Isayama (Mitsui Bussan Secure Directions, Inc.), |
CVE Identifier | CVE-2014-0112 - Incomplete fix for ClassLoader manipulation via ParametersInterceptor CVE-2014-0113 - ClassLoader manipulation via CookieInterceptor when configured to accept all cookies |
Problem
The default upload mechanism in Apache Struts 2 is based on Commons FileUpload version 1.3 which is vulnerable and allows DoS attacks. Additional ParametersInterceptor allows access to 'class' parameter which is directly mapped to getClass() method and allows ClassLoader manipulation.
Solution
In Struts 2.3.16.1, Commons FileUpload was updated to version 1.3.1 and "class" was added to excludeParams in struts-default.xml configuration of ParametersInterceptor.
Backward compatibility
No backward compatibility problems are expected.
Workaround
If you cannot upgrade to version 2.3.16.1 which is strongly advised, you can apply below workarounds:
Upgrade commons-fileupload
The fixed commons-fileupload library is a drop-in replacement for the vulnerable version. Deployed applications can be hardened by replacing the commons-fileupload jar file in WEB-INF/lib with the updated jar. For Maven
based Struts 2 projects, the following dependency needs to be added:
<dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3.1</version> </dependency>
Exclude 'class' parameter
Simple add '^class\.*' to the list of excludeParams as below
<interceptor-ref name="params"> <param name="excludeParams">^class\..*,^dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,^parameters\..*,^action:.*,^method:.*</param> </interceptor-ref>