What are common methods used by spammers to bypass graphical security measures in PHP forums?

Spammers often use automated bots to bypass graphical security measures, such as CAPTCHAs, in PHP forums by utilizing OCR (Optical Character Recognition) technology to read and input the characters. To combat this, one effective method is to implement a time-based token system where users must complete a task within a specific time frame, making it difficult for bots to automate the process. 

```php
// Generate a time-based token
$token = md5(uniqid(rand(), true));

// Store the token in a session variable
$_SESSION['token'] = $token;

// Display the token in a hidden form field
echo '<input type="hidden" name="token" value="' . $token . '">';
```

This code snippet generates a unique token based on the current time and stores it in a session variable. The token is then added to a hidden form field, which can be validated on form submission to ensure that the request was made within the allowed time frame.

Keywords

CAPTCHA image recognition OCR automated scripts spam bots

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