Threat Model Analysis for juliangarnier/anime

Threat: Threat 1: Indirect XSS via Target Selectors

Threat 1: Indirect XSS via Target Selectors
- Description: An attacker provides a crafted string as input that is used to define the targets property of an anime.js animation. This string contains a malicious CSS selector that, when processed by anime.js, results in the injection of attacker-controlled HTML or JavaScript into the DOM. For example, the attacker might use a selector like div[data-id='<img src=x onerror=alert(1)>'] if the data-id attribute is populated from user input.
- Impact: Execution of arbitrary JavaScript in the context of the victim's browser, leading to potential session hijacking, data theft, defacement, or phishing attacks.
- Affected Component: The targets property in the main anime() function and any functions that accept a targets parameter. This includes timeline functions.
- Risk Severity: Critical
- Mitigation Strategies:
  - Strict Input Validation: Validate user-provided input used for targets against a strict whitelist of allowed characters and patterns. Reject any input that contains potentially dangerous characters (e.g., <, >, ", ', /, (, )).
  - Selector Sanitization: Use a dedicated library or function to sanitize CSS selectors, ensuring they only target intended elements and do not contain malicious code.
  - Avoid Dynamic Selectors Based on User Input: If possible, avoid constructing selectors directly from user input. Instead, use pre-defined selectors or map user input to a safe set of allowed targets.
  - Content Security Policy (CSP): Implement a strong CSP to limit the impact of any successful XSS injection.

Threat: Threat 2: Indirect XSS via Animated Properties

Threat 2: Indirect XSS via Animated Properties
- Description: An attacker provides a crafted string as input that is used to set the value of an animated CSS property. If the application uses user input to directly set properties like innerHTML, outerHTML, or event handler attributes (e.g., onclick), the attacker can inject malicious HTML or JavaScript. Even properties like background-image could be exploited if the attacker can control the URL (e.g., url("javascript:alert(1)")).
- Impact: Execution of arbitrary JavaScript in the context of the victim's browser, leading to potential session hijacking, data theft, defacement, or phishing attacks.
- Affected Component: The property values passed to the anime() function (e.g., anime({ targets: '.el', translateX: userInput })). This applies to any property being animated.
- Risk Severity: Critical
- Mitigation Strategies:
  - Strict Input Validation: Validate user-provided input used for animated property values against a strict whitelist.
  - Context-Aware Escaping: Use appropriate escaping functions based on the context of the property being animated. For example, use HTML entity encoding for attribute values, CSS escaping for CSS property values, and URL encoding for URLs.
  - Avoid Unsafe Properties: Prefer animating safer properties like transform, opacity, color, etc., over properties that can directly execute code (e.g., innerHTML, event handlers). Use textContent instead of innerHTML whenever possible.
  - Content Security Policy (CSP): Implement a strong CSP.

Threat: Threat 3: Denial of Service via Excessive Animations

Threat 3: Denial of Service via Excessive Animations
- Description: An attacker provides input that triggers a large number of simultaneous animations, animates a very large number of DOM elements, or uses extremely long durations or complex easing functions. This overwhelms the browser's rendering engine, leading to performance degradation, unresponsiveness, or even browser crashes.
- Impact: The application becomes unusable for the victim, potentially affecting other users if the attack triggers server-side resource exhaustion (though this is less likely with client-side animations).
- Affected Component: The anime() function and any parameters that control the number of animated elements, animation duration, easing functions, and update frequency.
- Risk Severity: High
- Mitigation Strategies:
  - Limit Number of Animated Elements: Restrict the number of elements that can be animated simultaneously based on user input.
  - Limit Animation Duration: Set maximum limits on animation durations.
  - Restrict Easing Functions: Limit the complexity of user-selectable easing functions. Avoid custom easing functions based on user input.
  - Rate Limiting: Implement rate limiting on user actions that trigger animations.
  - Performance Testing: Thoroughly test the application's performance under stress.
  - Debouncing/Throttling: Debounce or throttle user input that triggers animations.