In website operation, user comments are an important part of community interaction, which can bring vitality to the content and enhance user stickiness.However, comment sections are often breeding grounds for potential security risks. Malicious users may inject HTML tags or JavaScript code into comment content to launch cross-site scripting (XSS) attacks, which not only damage the appearance of the website but may also steal user information or perform other malicious operations.Therefore, when displaying user comments, ensuring that the HTML tags in the comment content are safely handled is an issue that each website operator must pay close attention to.
AnQiCMS as an content management system that focuses on security and efficiency, provides us with reliable protection in this aspect.The core lies in the default handling mechanism of the template engine for content, as well as the additional tools provided to help us effectively prevent such risks.
AnQiCMS的安全基石：默认自动转义 (English)
AnQiCMS in displaying content rendered by the template engine, by default, will automatically escape HTML tags. This means that when users input similar<script>alert('XSS')</script>This code is, when AnQiCMS template engine will automatically convert it to<script>alert('XSS')</script>.The browser receives this escaped content and does not parse it as executable HTML or JavaScript code, but displays it purely as text.This is the important mechanism to prevent XSS attacks.
This automatic escaping feature is an integral core defense mechanism built into the AnQiCMS template engine, which greatly reduces the risk of a website being attacked due to malicious HTML code input by users.除非你明确指示模板引擎不要进行转义，否则任何从数据库中读取并显示在页面上的文本内容，其潜在的HTML标签都会被安全地处理。
When should extra attention be paid:safefilters andautoescapetags
Although AnQiCMS's template engine provides default security measures, you may encounter situations where you need to display unescaped HTML content, such as displaying complex layouts generated by rich text editors. AnQiCMS providessafefilters andautoescapeLabel to meet this kind of need.
safeThe filter can explicitly inform the template engine that the content in a certain variable is "safe", and no HTML escaping is needed. Its usage is usually{{ 变量名|safe }}.
whileautoescapeLabels can control the automatic escaping behavior of a template code block. For example,{% autoescape off %}...{% endautoescape %}this will close the automatic escaping inside this code block,{% autoescape on %}...{% endautoescape %}while this will force it to be enabled.
However, we must use these tools with great caution for the user-submitted comment content. Once we do not distinguish between them,safeThe filter is applied to user comments, or the comment display area is turned offautoescapeTherefore, any HTML or JavaScript code injected by malicious users may be executed by the browser, thus causing security vulnerabilities.When displaying user comments, it is strongly recommended to avoid usingsafeFilter or turn offautoescapeto maintain the default security strategy of AnQiCMS.
More thorough cleaning: strip HTML tags
If your website has strict plain text requirements for comment content, or you want to provide an additional layer of security, you can choose to strip the HTML tags from comments more thoroughly. The AnQiCMS template engine providesstriptagsandremovetagsAchieve this goal with the help of filters.
striptagsFilterThis filter will remove all HTML tags from the content, leaving only plain text. For example,{{ 评论内容|striptags }}all comments in<p>/<strong>/<a>All tags are deleted. This is very useful for comment areas that only want to display text.removetagsFilter: If you want to allow some HTML tags (such as<b>and<i>), but want to remove all other tags,removetagsCan be put to use. You can specify the tags to be removed, for example{{ 评论内容|removetags:"script,iframe,img" }}It can remove specific dangerous tags. However, to completely prevent all possible malicious tags and attributes, manual enumeration may be missing, so it is usually not asstriptagsOr by default, automatic escaping is thorough and secure.
Remember to add these filters when using them.|safeBecause the text processed by the filter is already safe, the template engine may still treat it as unprocessed text and escape it again, resulting in double escaping of HTML entities and affecting the display.
Markdown comment content security
AnQiCMS supports Markdown editor, allowing users to format text using Markdown syntax when publishing content.In the user comment scenario, if users are allowed to use Markdown, the system will first convert the Markdown content to HTML.AnQiCMS template engine will still perform default HTML escaping on itThis means that the converted HTML tags (including those converted from Markdown syntax), such as<p>/<strong>/<a>.|safeFilter.
If you want the Markdown comment format to display normally (i.e., the converted HTML is not escaped), while also ensuring safety, it usually requires more complex HTML sanitization (sanitization) processing on the server side, removing unsafe tags and attributes, and then passing the sanitized HTML to the template and using it|safeDisplay. Relying solely on front-end template filtering is not enough to cope with all attacks.
Backend management and content review: another line of defense
In addition to the technical guarantees provided by the template engine, the AnQiCMS backend management functions also provide important administrative means for comment security.The built-in "Content Security Management" and "Sensitive Word Filtering" functions can be reviewed and processed before or after the comment is published.Sensitive word filtering can automatically intercept comments containing specific vocabulary, while content security management allows administrators to manually review, delete, or modify comments.These features collectively constitute a multi-level security protection, helping website operators to control the security of comment content both in terms of technology and manual management.
In summary, AnQiCMS builds a solid first line of defense against security vulnerabilities in displaying user comments through its default automatic escaping feature of the template engine. As website operators, we should make full use of this feature and always be vigilant against inappropriate usesafeFilter orautoescapeThe risks that tags may bring. By combining the content review tools on the backend, we can provide users with an active and safe commenting interaction environment.
Common Questions (FAQ)
What are the situations where the automatic escaping feature of AnQiCMS template engine will be disabled in English?AnQiCMS template engine's default automatic escaping feature will be disabled in two main cases: one is when you explicitly use
|safeFilter, for example{{ item.Content|safe }}; the other is when you use{% autoescape off %}The label wraps a template code block, and all variables within this code block will no longer be automatically escaped.Strongly recommend avoiding disabling automatic escaping when displaying user-submitted comment content.If I want to allow users to use part of the HTML tags in comments (such as
<b>/<i>)，how should I do it?Directly controlling the allowed HTML tags at the template level and ensuring complete safety is complex and prone to errors. The template's|removetagsThe filter can remove tags from the list you specify, but this requires listing all allowed tags very carefully.The safer approach is to perform strict HTML sanitization (HTML Sanitization) on the user-submitted comment content on the backend (server side).