| Home > Security Bulletins > S2-046 |
Who should read this | All Struts 2 developers and users |
|---|---|
Impact of vulnerability | Possible RCE when performing file upload based on Jakarta Multipart parser |
Maximum security rating | Critical |
Recommendation | Upgrade to Struts 2.3.32 or Struts 2.5.10.1 |
Affected Software | Struts 2.3.5 - Struts 2.3.31, Struts 2.5 - Struts 2.5.10 |
Reporter | Chris Frohoff <cfrohoff at qualcomm dot com>, Nike Zheng <nike dot zheng at dbappsecurity dot com dot cn>, Alvaro Munoz <alvaro dot munoz at hpe dot com> |
CVE Identifier | CVE-2017-5638 |
It is possible to perform a RCE attack with a malicious Content-Disposition value or with improper Content-Length header. If the Content-Dispostion / Content-Length value is not valid an exception is thrown which is then used to display an error message to a user. This is a different vector for the same vulnerability described in S2-045 (CVE-2017-5638).
If you are using Jakarta based file upload Multipart parser, upgrade to Apache Struts version 2.3.32 or 2.5.10.1.
No backward incompatibility issues are expected.
You can switch to a different implementation of the Multipart parser. We have already prepared two plugins which can be used as a drop-in solution, please find them here. You can use them when you are running the Apache Struts 2.3.8 - 2.5.5 (in case of using the default Jakarta multipart parser) or the Apache Struts 2.3.20 - 2.5.5 (when using an alternative jakarta-stream multipart parser).
Another option is to remove the File Upload Interceptor from the stack, just define your own custom stack and set it as a default - please read How do we configure an Interceptor to be used with every Action. This will work only for Struts 2.5.8 - 2.5.10.
<interceptors>
<interceptor-stack name="defaultWithoutUpload">
<interceptor-ref name="exception"/>
<interceptor-ref name="alias"/>
<interceptor-ref name="servletConfig"/>
<interceptor-ref name="i18n"/>
<interceptor-ref name="prepare"/>
<interceptor-ref name="chain"/>
<interceptor-ref name="scopedModelDriven"/>
<interceptor-ref name="modelDriven"/>
<interceptor-ref name="checkbox"/>
<interceptor-ref name="datetime"/>
<interceptor-ref name="multiselect"/>
<interceptor-ref name="staticParams"/>
<interceptor-ref name="actionMappingParams"/>
<interceptor-ref name="params"/>
<interceptor-ref name="conversionError"/>
<interceptor-ref name="validation">
<param name="excludeMethods">input,back,cancel,browse</param>
</interceptor-ref>
<interceptor-ref name="workflow">
<param name="excludeMethods">input,back,cancel,browse</param>
</interceptor-ref>
<interceptor-ref name="debugging"/>
</interceptor-stack>
</interceptors>
<default-interceptor-ref name="defaultWithoutUpload"/>