Attack Surface: Denial of Service (DoS) via Resource Exhaustion
Description: Maliciously crafted input triggers excessively complex or long-running animations, overwhelming the client's browser. This is the most direct and likely attack vector related to anime.js.
How Anime.js Contributes: anime.js's core functionality is to create animations, and its flexibility allows for the creation of animations that can consume significant resources if parameters are not carefully controlled. The library directly enables this attack.
Example: A user-controlled input field directly sets the duration property of an anime.js animation. The user enters an extremely large number (e.g., 999999999999), causing the animation to run for an effectively infinite time, freezing the browser. Another example: a user controls the number of targets and sets it to a massive value, causing the browser to attempt to animate thousands or millions of elements simultaneously.
Impact: Client-side browser freeze or crash, rendering the application unusable for the affected user. This can impact other users if the attack is widespread or if it affects shared resources.
Risk Severity: High
Mitigation Strategies:
* Strict Input Validation: This is paramount. Always validate and limit all user-supplied values that influence any animation parameter. This includes:
* duration: Set a reasonable maximum duration (e.g., 5 seconds, 10 seconds). Use Math.min(userInput, maxDuration).
* iterations: Limit the number of times an animation repeats.
* targets: Limit the number of elements that can be animated simultaneously. This might involve validating the length of an array or the number of elements matched by a CSS selector.
* easing: Avoid overly complex easing functions if they are user-controllable.
* Rate Limiting: If animations are triggered by user actions (clicks, form submissions, etc.), implement rate limiting to prevent rapid, repeated triggering of animations. This prevents an attacker from repeatedly submitting malicious input to exacerbate the DoS.
* Complexity Caps: Implement hard limits on the overall complexity of animations. This could involve limiting the total number of keyframes, the nesting depth of timelines, or the combination of different animation properties.
* Server-Side Validation (if applicable): If animation parameters are generated or processed on the server, always perform validation there in addition to client-side validation. Client-side validation can be bypassed.
Attack Surface: Indirect Cross-Site Scripting (XSS) - (Low Probability, High Consequence, Directly Involves anime.js Input)
Description: Although anime.js doesn't directly execute JavaScript, if user input is used directly within anime.js's targets (CSS selectors) or to set CSS property values without proper sanitization, it creates a direct pathway for XSS. This is direct because the unsanitized input is passed into anime.js.
How Anime.js Contributes: anime.js accepts CSS selectors and property values as input. If these are sourced from unsanitized user input, anime.js becomes the conduit for the XSS attack, even though it's not executing the malicious code itself.
Example: An application allows users to input a "favorite color" which is then directly used as the value for a backgroundColor animation in anime.js. A malicious user enters: red; } body { background-image: url('malicious-site.com/steal-cookies.php'); } /*. If this input is not sanitized, the injected CSS could be used to steal cookies or perform other malicious actions. A more likely, but still low-probability, example involves manipulating the targets selector.
Impact: Execution of arbitrary JavaScript in the victim's browser, leading to potential session hijacking, data theft, website defacement, or other severe consequences.
Risk Severity: Low (probability) / Critical (impact)
Mitigation Strategies:
* Bulletproof Input Sanitization: This is absolutely essential. Use a robust, well-maintained HTML sanitization library (like DOMPurify) to sanitize any user-provided data that is used anywhere within anime.js calls, including:
* targets: Sanitize any user input used to construct CSS selectors.
* Property values: Sanitize any user input used to set CSS property values (e.g., translateX, backgroundColor, opacity).
* Content Security Policy (CSP): A strong CSP is a crucial defense-in-depth measure. Restrict script-src to trusted sources. Use style-src directives to limit the injection of inline styles, which can be a vector for XSS even when manipulating CSS properties.
* Avoid Direct User Input for Targets: The safest approach is to avoid using user-provided strings directly as anime.js targets. Instead:
* Use pre-defined, safe selectors (e.g., IDs or class names that you control).
* If users need to select elements, provide a controlled set of options (e.g., a dropdown list) rather than allowing free-form text input.
* Output Encoding: While primarily relevant for displaying user data, always use appropriate output encoding (e.g., HTML entity encoding) when rendering user-provided content, even if it's not directly used within anime.js. This helps prevent XSS vulnerabilities in other parts of the application.