网安入门07-Sql注入（二次注入）

发布时间：2023年12月29日

渗透测试简介

黑盒测试：看不到后端代码，只能依靠前端页面显示来判断是否有注入点
白盒测试：可以看到后端代码，进行代码审计分析注入点
白＋黑：既可以看到后端代码，也可以看到前端页面的回显
实战中黑盒占80%，客户提供源码白盒占5%，通过漏洞挖出源代码白＋黑15%

二次注入

Less24

试图进行常规注入

触发过滤机制，页面回显如下（滚开，你个愚蠢的黑客）

点击忘记密码：

注册账号页面，先试一下admin用户

不让我注册！那我先注册一个admin‘#用户，密码123

然后登录admin’#

改一手密码

最后再用admin账号和刚改好的密码222，就登录成功啦！

原理

查看源代码，最重要的三个页面：登录，注册，改密码

其中login.php是登录页面，login_crearte.php是注册页面，pass_change.php是改密码页面

login.php：

<html>
<head>
</head>
<body bgcolor="#000000">
<font size="3" color="#FFFF00">
<div align="right">
<a style="font-size:.8em;color:#FFFF00" href='index.php'><img src="../images/Home.png" height='45'; width='45'></br>HOME</a>
</div>
<?PHP

session_start();
//including the Mysql connect parameters.
include("../sql-connections/sql-connect.php");

function sqllogin(){

   $username = mysql_real_escape_string($_POST["login_user"]);#' " \
   $password = mysql_real_escape_string($_POST["login_password"]);
   $sql = "SELECT * FROM users WHERE username='$username' and password='$password'";
//$sql = "SELECT COUNT(*) FROM users WHERE username='$username' and password='$password'";
   $res = mysql_query($sql) or die('You tried to be real smart, Try harder!!!! :( ');
   $row = mysql_fetch_row($res);
	//print_r($row) ;
   if ($row[1]) {
			return $row[1];
   } else {
      		return 0;
   }

}

$login = sqllogin();
if (!$login== 0) 
{
	$_SESSION["username"] = $login;
	setcookie("Auth", 1, time()+3600);  /* expire in 15 Minutes */
	header('Location: logged-in.php');
} 
else
{
?>
<tr><td colspan="2" style="text-align:center;"><br/><p style="color:#FF0000;">
<center>
<img src="../images/slap1.jpg">
</center>
</p></td></tr>
<?PHP
} 
?>

</body>
</html>

login_crearte.php：

<html>
<head>
</head>
<body bgcolor="#000000">
<?PHP
session_start();
?>
<div align="right">
<a style="font-size:.8em;color:#FFFF00" href='index.php'><img src="../images/Home.png" height='45'; width='45'></br>HOME</a>
</div>
<?php

//including the Mysql connect parameters.
include("../sql-connections/sql-connect.php");


if (isset($_POST['submit']))
{
# Validating the user input........

	//$username=  $_POST['username'] ;
	$username=  mysql_escape_string($_POST['username']) ;
	$pass= mysql_escape_string($_POST['password']);
	$re_pass= mysql_escape_string($_POST['re_password']);
	
	echo "<font size='3' color='#FFFF00'>";
	$sql = "select count(*) from users where username='$username'";
	$res = mysql_query($sql) or die('You tried to be smart, Try harder!!!! :( ');
  	$row = mysql_fetch_row($res);
	
	//print_r($row);
	if (!$row[0]== 0) 
		{
		?>
		<script>alert("The username Already exists, Please choose a different username ")</script>;
		<?php
		header('refresh:1, url=new_user.php');
   		} 
		else 
		{
       		if ($pass==$re_pass)
			{
				# Building up the query........
   				
   				$sql = "insert into users ( username, password) values(\"$username\", \"$pass\")";
   				mysql_query($sql) or die('Error Creating your user account,  : '.mysql_error());
					echo "</br>";
					echo "<center><img src=../images/Less-24-user-created.jpg><font size='3' color='#FFFF00'>";   				
					//echo "<h1>User Created Successfully</h1>";
					echo "</br>";
					echo "</br>";
					echo "</br>";					
					echo "</br>Redirecting you to login page in 5 sec................";
					echo "<font size='2'>";
					echo "</br>If it does not redirect, click the home button on top right</center>";
					header('refresh:5, url=index.txt');
			}
			else
			{
			?>
			<script>alert('Please make sure that password field and retype password match correctly')</script>
			<?php
			header('refresh:1, url=new_user.php');
			}
		}
}


?>

</body>
</html>

pass_change.php：

<html>
<head>
</head>
<body bgcolor="#000000">
<?PHP
session_start();
if (!isset($_COOKIE["Auth"]))
{
	if (!isset($_SESSION["username"])) 
	{
   		header('Location: index.txt');
	}
	header('Location: index.txt');
}
?>
<div align="right">
<a style="font-size:.8em;color:#FFFF00" href='index.php'><img src="../images/Home.png" height='45'; width='45'></br>HOME</a>
</div>
<?php

//including the Mysql connect parameters.
include("../sql-connections/sql-connect.php");


if (isset($_POST['submit']))
{
	
	
	# Validating the user input........
	$username= $_SESSION["username"];  #admin'#
	$curr_pass= mysql_real_escape_string($_POST['current_password']);
	$pass= mysql_real_escape_string($_POST['password']);
	$re_pass= mysql_real_escape_string($_POST['re_password']);
	
	if($pass==$re_pass)
	{	
		$sql = "UPDATE users SET PASSWORD='$pass' where username='$username' and password='$curr_pass' ";
		$res = mysql_query($sql) or die('You tried to be smart, Try harder!!!! :( ');
		$row = mysql_affected_rows();
		echo '<font size="3" color="#FFFF00">';
		echo '<center>';
		if($row==1)
		{
			echo "Password successfully updated";
	
		}
		else
		{
			header('Location: failed.php');
			//echo 'You tried to be smart, Try harder!!!! :( ';
		}
	}
	else
	{
		echo '<font size="5" color="#FFFF00"><center>';
		echo "Make sure New Password and Retype Password fields have same value";
		header('refresh:2, url=index.txt');
	}
}
?>
<?php
if(isset($_POST['submit1']))
{
	session_destroy();
	setcookie('Auth', 1 , time()-3600);
	header ('Location: index.txt');
}
?>
</center>  
</body>
</html>

前面两个页面都有mysql_real_escape_string()的严格的过滤，无法进行注入

PHP mysqli_real_escape_string() 函数-菜鸟教程

突破点就在登录成功之后的这个地方

由于过滤只在进行sql查询的地方触发，过滤后还是以没被过滤的形式存入数据库的，在重置密码时就可以进行二次注入，admin’#进行闭合，注释了后面的语句，这样我们就成功改掉了admin的密码，得到所有权限了

文章来源:https://blog.csdn.net/m0_61499194/article/details/135197393
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