Unsanitized user input in raw HTML strings (XSS)

• Rule ID: python_lang_raw_html_using_user_input
• Languages: python
• Source: raw_html_using_user_input.yml

Description

Including unsanitized user input in HTML exposes your application to cross-site scripting (XSS) attacks. This vulnerability allows attackers to inject malicious scripts into web pages viewed by other users.

Remediations

• Do not include user input directly in HTML strings. This practice can lead to XSS vulnerabilities.

  html = f"<h1>{user_input}</h1>" # unsafe

• Do use a framework or templating language that automatically handles the encoding and sanitization of user input when constructing HTML. This approach minimizes the risk of XSS attacks.
• Do sanitize user input if you must use HTML strings directly. Utilize libraries designed for input sanitization to ensure that user input does not contain malicious content.

  from html_sanitizer import Sanitizer
  
  sanitizer = Sanitizer()
  sanitized_value = sanitizer.sanitize(user_input)
  html = f"<h1>{sanitized_value}</h1>"

References

• OWASP Cross-Site Scripting (XSS) Cheatsheet

Associated CWE

• CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

OWASP Top 10

• A03:2021 - Injection

Configuration

To skip this rule during a scan, use the following flag

bearer scan /path/to/your-project/ --skip-rule=python_lang_raw_html_using_user_input

To run only this rule during a scan, use the following flag

bearer scan /path/to/your-project/ --only-rule=python_lang_raw_html_using_user_input