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Detailed explanation of php curl simulation submission method with csrf token verification

  • 2021-09-16 06:34:39
  • OfStack

Usually, a random token value is added to the form for security purposes to prevent csrf attacks.

It is not difficult to simulate submitting a website with token authentication.

1. Get token through regularization
2. Submit the token simulation with the retrieved token

The following is a successful example

Directory structure 


 The  form.php  Forms that need to be impersonated  
 The  getForm.php  In fact, in fact, the   Simulated submitter  
 The  post.php  Form validator  
 The  
 Off- cookie  In fact, in fact, the  cookie Storage directory

getForm.php 


<?php
$cookie_file = './cookie/'.time().'.cookie';
$str = getResponse('http://a.curl.com:81/form.php',[],$cookie_file);
setcookie("PHPSESSID", "vc0heoa6lfsi3gger54pkns152");
preg_match('/<input name="token" type="hidden" value="(.*)"/U', $str, $match);

$post['token'] = $match[1];
$post['name'] = '3333333';
$post['password'] = '12121213';
print_r(getResponse('http://a.curl.com:81/post.php', $post, $cookie_file));

function getResponse($url, $data=[], $cookie_file='', $timeout = 3)
  {
    if(empty($cookie_file))
    {
      $cookie_file = '.cookie';
    }

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_REFERER, "https://www.baidu.com");  // Structural origin 
    curl_setopt($ch, CURLOPT_USERAGENT,"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.59 Safari/537.36");

    if(!empty($data))
    {
      curl_setopt($ch, CURLOPT_POST, true);
      curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
    }
    curl_setopt($ch, CURLOPT_COOKIEJAR, $cookie_file);//  Take cookie The parameters of are 
    curl_setopt ($ch, CURLOPT_COOKIEFILE, $cookie_file); // Send cookie
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $timeout);
    try
    {
       $handles = curl_exec($ch);
       curl_close($ch);
       return $handles;
    }
    catch (Exception $e)
    {
      echo 'Caught exception: ', $e->getMessage(), "\n";
    }
    unlink($cookie_file);
  }

form.php 


<?php
session_start();
$_SESSION['token'] = md5($_SERVER['REQUEST_TIME']);
$_SESSION['time'] = date("Y-m-d H:i:s");
session_write_close();
//echo $_SESSION['auth'];
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
 <title> new document </title>
 <meta name="generator" content="editplus" />
 <meta name="author" content="" />
 <meta name="keywords" content="" />
 <meta name="description" content="" />
 </head>
 <body>
<form action="post.php" method="post">
  <p><input name="name" type="text"></p>
  <p><input name="password" type="password"></p>
  <p><input name="token" type="hidden" value="<?php echo $_SESSION['token']?>"></p>
  <p><input type="submit"></p>
</form>
 </body>
</html>

post.php 


<?php
session_start();
if(empty($_POST['token']))
{
  exit ("token is empty!");
}

if(empty($_SESSION['token']))
{
 exit ("session is empty");
}

if($_POST['token'] != $_SESSION['token'])
{
  exit ("token ");
} else
{
  unset($_SESSION['token']);
}

echo PHP_EOL;
echo "pass";
print_r($_REQUEST);

echo PHP_EOL;
print_r($_SERVER);
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