Межсайтовый скриптинг in Java

Высокий CWE-79 Draft — pending review

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Простыми словами

Imagine a bulletin board where someone posts an instruction that forces the viewer's computer to secretly send their session cookie to an attacker.

output encoding: Converting special markup characters into safe entities so browsers display them as text rather than script.

Что происходит

XSS in Java web applications occurs when JSP, Thymeleaf, or FreeMarker templates render request parameters directly into response streams without encoding.

Реальные последствия

In 2005, the Samy XSS worm infected over 1 million user profiles on MySpace in under 20 hours, forcing the platform offline.

Documented historical AppSec case study.

Уязвимый код vs Безопасный

VULNERABLE



  Welcome, <%= request.getParameter("name") %>

FIXED



  Welcome,

Почему исправление работает

JSTL and Thymeleaf th:text convert sensitive HTML characters (<, >, &, ") into inert HTML entities.

Подводные камни языка

Thymeleaf th:utext

th:utext explicitly disables escaping. Use th:text for untrusted data.

Распространенные заблуждения

"Spring Boot automatically prevents all XSS"

Spring handles URL and JSON encoding, but template rendering depends on proper tag usage.

Как проверить свой код

grep -rn "<%=.*getParameter" --include="*.jsp" . grep -rn "th:utext" --include="*.html" .

Scan JSP and template views using FindSecBugs (rule XSS_REQUEST_PARAMETER_TO_JSP_WRITER).

Чек-лист по безопасности

✓Use in JSP or th:text in Thymeleaf
✓Run FindSecBugs in CI to catch unescaped output

Часто задаваемые вопросы

How should rich user HTML be handled in Java?

Use OWASP Java HTML Sanitizer to strip dangerous tags and attributes before rendering.

Источники и ссылки

Смотреть на: Java Python JavaScript Java Go PHP C# Rust

Смотрите также: SQL Injection Command InjectionPath Traversal