Apache Struts 2 framework REST plugin insecurely deserializes untrusted XML data

2017-09-06T00:00:00
ID VU:112992
Type cert
Reporter CERT
Modified 2017-09-06T00:00:00

Description

Overview

Apache Struts 2 framework, versions 2.5 to 2.5.12, with REST plugin insecurely deserializes untrusted XML data. A remote, unauthenticated attacker can leverage this vulnerability to execute arbitrary code in the context of the Struts application.

Description

CWE-502: Deserialization of Untrusted Data - CVE-2017-9805

In Apache Struts 2 framework, versions 2.5 to 2.5.12, the REST plugin uses XStreamHandler with an instance of XStream to deserialize XML data. Because there is no type filtering, a remote, unauthenticated attacker may send a specially crafted XML payload to execute arbitrary code in the context of the Struts application.

Refer to the researcher's blog post for more information about this vulnerability. A Metasploit module with exploit code is publicly available.


Impact

A remote, unauthenticated attacker may send a specially crafted XML payload to execute arbitrary code on vulnerable servers in the context of the Struts application.


Solution

Apply an update

The vendor has released version 2.5.13 to address this vulnerability. No workaround is possible according to the vendor, so patching is strongly recommended.


Remove or limit the REST plugin

If it is not used, consider removing the REST plugin. Per the vendor, it is also possible to limit its functionality to normal server pages or JSON with the following configuration change in struts.xml:

<constant name="struts.action.extension" value="xhtml,,json" />


Vendor Information

Vendor| Status| Date Notified| Date Updated
---|---|---|---
Apache Struts| | -| 06 Sep 2017
If you are a vendor and your product is affected, let us know.

CVSS Metrics

Group | Score | Vector
---|---|---
Base | 10.0 | AV:N/AC:L/Au:N/C:C/I:C/A:C
Temporal | 8.3 | E:F/RL:OF/RC:C
Environmental | 8.3 | CDP:ND/TD:H/CR:ND/IR:ND/AR:ND

References

  • <https://cwe.mitre.org/data/definitions/502.html>
  • <https://struts.apache.org/docs/s2-052.html>
  • <https://lgtm.com/blog/apache_struts_CVE-2017-9805>
  • <https://github.com/rapid7/metasploit-framework/pull/8924/files>

Credit

Man Yue Mo of lgtm is credited with reporting this vulnerability to the vendor.

This document was written by Joel Land.

Other Information

  • CVE IDs: CVE-2017-9805
  • Date Public: 05 Sep 2017
  • Date First Published: 06 Sep 2017
  • Date Last Updated: 06 Sep 2017
  • Document Revision: 13