DVWA靶場通關----(1) Brute Force教程
Brute Force(暴力破解)
Brute Force(暴力破解),就是指黑客利用黑客字典,通過窮舉法猜測使用者口令。
Brute Force主題:
Low
原始碼解析
<?php //檢查變數是否設定(先看有沒有Login引數) if( isset( $_GET[ 'Login' ] ) ) { //獲取使用者 $user = $_GET[ 'username' ]; //獲取密碼 $pass = $_GET[ 'password' ]; //將密碼使用md5加密 $pass = md5( $pass ); //構建SQL語句,查詢結果儲存在query變數中 $query = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';"; //資料庫查詢,將查詢結果儲存在result變數中,查到了,儲存使用者具體資訊;未查到,就在頁面上輸入錯誤結果,result為空 $result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' ); //結果存在並且返回一條記錄,說明查到了 if( $result && mysqli_num_rows( $result ) == 1 ) { //查詢結果關聯資料row,row已經變成鍵值對 $row = mysqli_fetch_assoc( $result ); //獲取登入成功圖片 $avatar = $row["avatar"]; // Login successful //登入成功,輸出到頁面上 echo "<p>Welcome to the password protected area {$user}</p>"; echo "<img src=\"{$avatar}\" />"; } else { // Login failed //未查到,錯誤資訊輸出到頁面上 echo "<pre><br />Username and/or password incorrect.</pre>"; } //釋放資源 ((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res); } ?>
漏洞復現
(1)先隨便輸入一個使用者名稱和密碼,使用burp抓包
在這裡我們可以看到是使用get獲取引數,且是明文傳輸,沒有驗證碼類的驗證機制,所以可以使用爆破。
(2)抓到包後,右鍵點選Send to Intruder,將抓到的包轉到Intruder
將抓到的包傳送到Intruder時,會存在很多變數,在頁面右側可以將他們全部清理掉,然後在存在爆破點的地方再新增上我們想要他存在的變數。
選擇合適的攻擊型別,在這裡我選擇的是第四個:Cluster bomb
(關於四個攻擊型別的簡介,有想要了解的朋友可以看我另一篇帖子:https://www.cnblogs.com/cc-qy/p/15693286.html)
(3)成功
在上面的Cluster bomb中的截圖中我們可以看到,成功到找到了使用者的賬號密碼,像這種正確的賬戶密碼,我們可以通過後面的Length進行判斷,一般正確的都是唯一的
Medium
原始碼解析
<?php //是否存在Login變數(標籤裡面的name),檢查是否存在Login按鈕 if( isset( $_GET[ 'Login' ] ) ) { // Sanitise username input //獲取使用者名稱,存入user變數裡 $user = $_GET[ 'username' ]; //user中x00,n,r,,’,”,x1a轉義,防SQL注入 $user = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $user ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); // Sanitise password input $pass = $_GET[ 'password' ]; //pass中x00,n,r,,’,”,x1a轉義,防SQL注入 $pass = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $pass ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); //密碼加密 $pass = md5( $pass ); // Check the database $query = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';"; $result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' ); if( $result && mysqli_num_rows( $result ) == 1 ) { // Get users details $row = mysqli_fetch_assoc( $result ); $avatar = $row["avatar"]; // Login successful echo "<p>Welcome to the password protected area {$user}</p>"; echo "<img src=\"{$avatar}\" />"; } else { // Login failed,失敗後會延時2s sleep( 2 ); echo "<pre><br />Username and/or password incorrect.</pre>"; } ((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res); } ?>
漏洞復現
關於Medium難度,它的原始碼中對於登入這一方面並沒有做太多的改動,因此它的爆破過程與Low難度的過程基本一樣,想要嘗試的朋友可以參考Low難度中的爆破過程,區別是每一次登入失敗後會延時2s,別的就沒有什麼改動了,總體過程影響不大。
另外在這個Medium難度的原始碼中,它對防止注入做了很多的工作,像比如說,它使用了mysql_real_escape_string 函式,這個函式可以對字串中的函式進行轉義,一定程度上可以防止sql注入,到這個地方會不會想到在Low難度中是否可以通過注入來繞過,可以去試一下。(我在這個地方用了萬能密碼發現是可以的,在Username處:admin' or '1'='1,在Password處隨便填點東西,像123這樣的都行,這樣就可以成功登陸了)
High
原始碼解析
<?php if( isset( $_POST[ 'Login' ] ) && isset ($_POST['username']) && isset ($_POST['password']) ) { // Check Anti-CSRF token checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' ); // Sanitise username input $user = $_POST[ 'username' ]; $user = stripslashes( $user ); $user = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $user ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); // Sanitise password input $pass = $_POST[ 'password' ]; $pass = stripslashes( $pass ); $pass = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $pass ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); $pass = md5( $pass ); // Default values $total_failed_login = 3; $lockout_time = 15; $account_locked = false; // Check the database (Check user information) //如果在鎖定狀態就輸出已被鎖定 $data = $db->prepare( 'SELECT failed_login, last_login FROM users WHERE user = (:user) LIMIT 1;' ); $data->bindParam( ':user', $user, PDO::PARAM_STR ); $data->execute(); $row = $data->fetch(); // Check to see if the user has been locked out. if( ( $data->rowCount() == 1 ) && ( $row[ 'failed_login' ] >= $total_failed_login ) ) { // User locked out. Note, using this method would alLow for user enumeration! //echo "<pre><br />This account has been locked due to too many incorrect logins.</pre>"; // Calculate when the user would be alLowed to login again //計算使用者能再次登入的時間 $last_login = strtotime( $row[ 'last_login' ] ); $timeout = $last_login + ($lockout_time * 60); $timenow = time(); /* print "The last login was: " . date ("h:i:s", $last_login) . "<br />"; print "The timenow is: " . date ("h:i:s", $timenow) . "<br />"; print "The timeout is: " . date ("h:i:s", $timeout) . "<br />"; */ // Check to see if enough time has passed, if it hasn't locked the account if( $timenow < $timeout ) { $account_locked = true; // print "The account is locked<br />"; } } // Check the database (if username matches the password) $data = $db->prepare( 'SELECT * FROM users WHERE user = (:user) AND password = (:password) LIMIT 1;' ); $data->bindParam( ':user', $user, PDO::PARAM_STR); $data->bindParam( ':password', $pass, PDO::PARAM_STR ); $data->execute(); $row = $data->fetch(); // If its a valid login... if( ( $data->rowCount() == 1 ) && ( $account_locked == false ) ) { // Get users details $avatar = $row[ 'avatar' ]; $failed_login = $row[ 'failed_login' ]; $last_login = $row[ 'last_login' ]; // Login successful echo "<p>Welcome to the password protected area <em>{$user}</em></p>"; echo "<img src=\"{$avatar}\" />"; // Had the account been locked out since last login? if( $failed_login >= $total_failed_login ) { echo "<p><em>Warning</em>: Someone might of been brute forcing your account.</p>"; echo "<p>Number of login attempts: <em>{$failed_login}</em>.<br />Last login attempt was at: <em>${last_login}</em>.</p>"; } // Reset bad login count $data = $db->prepare( 'UPDATE users SET failed_login = "0" WHERE user = (:user) LIMIT 1;' ); $data->bindParam( ':user', $user, PDO::PARAM_STR ); $data->execute(); } else { // Login failed sleep( rand( 2, 4 ) ); // Give the user some feedback echo "<pre><br />Username and/or password incorrect.<br /><br/>Alternative, the account has been locked because of too many failed logins.<br />If this is the case, <em>please try again in {$lockout_time} minutes</em>.</pre>"; // Update bad login count $data = $db->prepare( 'UPDATE users SET failed_login = (failed_login + 1) WHERE user = (:user) LIMIT 1;' ); $data->bindParam( ':user', $user, PDO::PARAM_STR ); $data->execute(); } // Set the last login time $data = $db->prepare( 'UPDATE users SET last_login = now() WHERE user = (:user) LIMIT 1;' ); $data->bindParam( ':user', $user, PDO::PARAM_STR ); $data->execute(); } // Generate Anti-CSRF token generateSessionToken(); ?>
漏洞復現
在這個難度中,首先從程式碼中可以發現是加了token驗證的。針對這種帶有token驗證的,我們也可以使用Burp去爆破,接下來是具體的一些步驟:
(1)經典抓包,在這個頁面中很容易看到了token值
(2)在Intruder中,攻擊型別選擇Pitchfork,後面的變數一個是password,另一個是token值
(3)關於第一個變數password的字典,就不在詳細說了,詳細說一下變數token值得處理
設定執行緒數為1
點了ok按鈕後會在那個ADD按鈕後面新增生成的那個正則表示式,不用管,新增上就行,沒新增上的多試幾次(在這裡有一個點是剛開始抓的包不要釋放,否則這個地方獲取不到程式碼)
在這個地方注意選擇Always
(3)看效果
Impossible
原始碼分析
// 檢驗 token
checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );
// 過濾 username 和 password
$user = $_POST[ 'username' ];
$user = stripslashes( $user );
$user = mysql_real_escape_string( $user );
$pass = $_POST[ 'password' ];
$pass = stripslashes( $pass );
$pass = mysql_real_escape_string( $pass );
$pass = md5( $pass );
// 失敗登入次數 3 鎖定時間單位 15 賬戶鎖定
$total_failed_login = 3;
$lockout_time = 15;
$account_locked = false;
// 驗證使用者名稱和密碼
$data = $db->prepare( 'SELECT failed_login, last_login FROM users WHERE user = (:user) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR );
$data->execute();
$row = $data->fetch();
// 檢查使用者是否已被鎖定.
if( ( $data->rowCount() == 1 ) && ( $row[ 'failed_login' ] >= $total_failed_login ) ) {
// 登入失敗超過 3 次 15 分鐘再嘗試
$last_login = $row[ 'last_login' ];
$last_login = strtotime( $last_login );
$timeout = strtotime( "{$last_login} +{$lockout_time} minutes" );
$timenow = strtotime( "now" );
// 檢查是否已經過了足夠的時間,是否沒有鎖定帳戶
if( $timenow > $timeout )
$account_locked = true;
}
// 檢驗使用者名稱和密碼
$data = $db->prepare( 'SELECT * FROM users WHERE user = (:user) AND password = (:password) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR);
$data->bindParam( ':password', $pass, PDO::PARAM_STR );
$data->execute();
$row = $data->fetch();
// 如果登入有效
if( ( $data->rowCount() == 1 ) && ( $account_locked == false ) ) {
// 獲取使用者頭像、登入測試、和最近登入
$avatar = $row[ 'avatar' ];
$failed_login = $row[ 'failed_login' ];
$last_login = $row[ 'last_login' ];
// 輸出登入成功資訊
echo "<p>Welcome to the password protected area <em>{$user}</em></p>";
echo "<img src=\"{$avatar}\" />";
// 自上次登入後帳戶是否已被鎖定?
if( $failed_login >= $total_failed_login ) {
echo "<p><em>Warning</em>: Someone might of been brute forcing your account.</p>";
echo "<p>Number of login attempts: <em>{$failed_login}</em>.<br />Last login attempt was at: <em>${last_login}</em>.</p>";
}
// 重置登入失敗次數
$data = $db->prepare( 'UPDATE users SET failed_login = "0" WHERE user = (:user) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR );
$data->execute();
}
else {
// 登入失敗隨機延時並輸出返回資訊
sleep( rand( 2, 4 ) );
echo "<pre><br />Username and/or password incorrect.<br /><br/>Alternative, the account has been locked because of too many failed logins.<br />If this is the case, <em>please try again in {$lockout_time} minutes</em>.</pre>";
// 更新登入失敗數
$data = $db->prepare( 'UPDATE users SET failed_login = (failed_login + 1) WHERE user = (:user) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR );
$data->execute();
}
// 設定最後的登入時間
$data = $db->prepare( 'UPDATE users SET last_login = now() WHERE user = (:user) LIMIT 1;' );
$data->bindParam( ':user', $user, PDO::PARAM_STR );
$data->execute();
這個難度是最高的難度,其中的改變都有GET提交方式改為POST提交方式,同樣加了token校驗機制,還有就是他限制的登入的次數,如果登入失敗3次,賬戶就會被鎖定,需要等待15,然後才能重新嘗試。
以上就是這個靶場中,個人的一些筆記整理,歡迎各位大佬互相交流學習,有不對的地方勿噴。