Dvwa教程之跨站偽造請求(三)
阿新 • • 發佈：2020-08-04
Low CSRF Source
<?php if( isset( $_GET[ 'Change' ] ) ) { // Get input $pass_new = $_GET[ 'password_new' ]; $pass_conf = $_GET[ 'password_conf' ]; // Do the passwords match? if( $pass_new == $pass_conf ) { // They do! $pass_new = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $pass_new ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); $pass_new = md5( $pass_new ); // Update the database $insert= "UPDATE `users` SET password = '$pass_new' WHERE user = '" . dvwaCurrentUser() . "';"; $result = mysqli_query($GLOBALS["___mysqli_ston"], $insert ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' ); // Feedback for the user echo "<pre>Password Changed.</pre>"; } else { // Issue with passwords matching echo "<pre>Passwords did not match.</pre>"; } ((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res); }
可以看到，伺服器收到修改密碼的請求後，會檢查引數password_new與password_conf是否相同，如果相同，就會修改密碼，並沒有任何的防CSRF機制
直接利用
http://192.168.0.115/dvwa-master/vulnerabilities/csrf/?password_new=aaa&password_conf=aaa&Change=Change#
誘導受害者直接點選這個連線就可以修改密碼
Medium CSRF Source
1 <?php 2 3 if( isset( $_GET[ 'Change' ] ) ) { 4 // Checks to see where the request came from 5 if( stripos( $_SERVER[ 'HTTP_REFERER' ] ,$_SERVER[ 'SERVER_NAME' ]) !== false ) { 6 // Get input 7 $pass_new = $_GET[ 'password_new' ]; 8 $pass_conf = $_GET[ 'password_conf' ]; 9 10 // Do the passwords match? 11 if( $pass_new == $pass_conf ) { 12 // They do! 13 $pass_new = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $pass_new ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); 14 $pass_new = md5( $pass_new ); 15 16 // Update the database 17 $insert = "UPDATE `users` SET password = '$pass_new' WHERE user = '" . dvwaCurrentUser() . "';"; 18 $result = mysqli_query($GLOBALS["___mysqli_ston"], $insert ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' ); 19 20 // Feedback for the user 21 echo "<pre>Password Changed.</pre>"; 22 } 23 else { 24 // Issue with passwords matching 25 echo "<pre>Passwords did not match.</pre>"; 26 } 27 } 28 else { 29 // Didn't come from a trusted source 30 echo "<pre>That request didn't look correct.</pre>"; 31 } 32 33 ((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res); 34 } 35 36 ?>
Medium 級別的程式碼加入了來源檢查
設定了來源檢查
用burp檢視資料包
多了一個欄位Referer， 服務端程式碼中會去對比這個欄位判斷一下來源，
可以直接在burp直接新增這個欄位就可以修改成功
High CSRF Source
<?php
if( isset( $_GET[ 'Change' ] ) ) {
// Check Anti-CSRF token
checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );
// Get input
$pass_new = $_GET[ 'password_new' ];
$pass_conf = $_GET[ 'password_conf' ];
// Do the passwords match?
if( $pass_new == $pass_conf ) {
// They do!
$pass_new = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $pass_new ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));
$pass_new = md5( $pass_new );
// Update the database
$insert = "UPDATE `users` SET password = '$pass_new' WHERE user = '" . dvwaCurrentUser() . "';";
$result = mysqli_query($GLOBALS["___mysqli_ston"], $insert ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' );
// Feedback for the user
echo "<pre>Password Changed.</pre>";
}
else {
// Issue with passwords matching
echo "<pre>Passwords did not match.</pre>";
}
((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);
}
// Generate Anti-CSRF token
generateSessionToken();
?>
可以看到，High級別的程式碼加入了Anti-CSRF token機制，使用者每次訪問改密頁面時，伺服器會返回一個隨機的token，向伺服器發起請求時，需要提交token引數，而伺服器在收到請求時，會優先檢查token，只有token正確，才會處理客戶端的請求。漏洞利用 由於跨域是不能實現的，所以我們要將攻擊程式碼注入到目標伺服器localhost中，才有可能完成攻擊。所以單純從CSRF未能突破High級別。
Impossible CSRF Source
可以看到，Impossible級別的程式碼利用PDO技術防禦SQL注入，至於防護CSRF，則要求使用者輸入原始密碼（簡單粗暴），攻擊者在不知道原始密碼的情況下，無論如何都無法進行CSRF攻擊。