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43 lines
1.5 KiB
Markdown
43 lines
1.5 KiB
Markdown
# TaintedTextWithQuotes
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Emitted when user-controlled input that can contain quotation marks can be passed into to an `echo` statement.
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## Risk
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This could lead to a potential Cross Site Scripting (XSS) vulnerability. Using a XSS vulnerability, an attacker could inject malicious JavaScript and execute any action JavaScript could do. Examples include:
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- Stealing authentication material (e.g. cookies, JWT tokens)
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- Exfiltrate sensitive information by reading the DOM
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- Keylog entries on the website (e.g. fake login form)
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Whether this is exploitable or not depends on a few conditions:
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- Is an executable mimetype set? (e.g. `text/html`)
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- Is the content served inline or as attachment? (`Content-Disposition`)
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- Is the output properly sanitized? (e.g. stripping all HTML tags or having an allowlist of allowed characters)
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## Example
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```php
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<?php
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$param = strip_tags($_GET['param']);
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?>
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<script>
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console.log('<?=$param?>')
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</script>
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```
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Passing `');alert('injection');//` as a `GET` param here would cause the `alert` to trigger.
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## Mitigations
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- Sanitize user input by using functions such as `htmlentities` with the `ENT_QUOTES` flag or use an allowlist.
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- Set all cookies to `HTTPOnly`.
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- Consider using Content Security Policy (CSP), to limit the risk of XSS vulnerabilities.
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## Further resources
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- [OWASP Wiki for Cross Site Scripting (XSS)](https://owasp.org/www-community/attacks/xss/)
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- [Content-Security-Policy - Web Fundamentals](https://developers.google.com/web/fundamentals/security/csp)
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