What are the security requirements and risks for runtime script loading in Lightning components?
Answer
**Security Requirements for Runtime Script Loading:**
1. All scripts must be included in static resources and loaded using a `$Resource` URL.
2. Dynamically loading third-party JavaScript files from external sources like CDNs is not allowed.
3. Ensure proper version control and prevent unauthorized code changes.
4. Avoid using unsafe attributes and sanitize user-controlled data.
5. Adhere to LockerService requirements to maintain secure isolation.
**Security Risks of Dynamic Loading:**
Dynamically loading JavaScript from a URL stored in a custom setting is risky because it can lead to executing untrusted code, potentially causing vulnerabilities like cross-site scripting (XSS) or code injection. If the URL is compromised or altered, malicious code could be introduced. Salesforce prohibits this practice to avoid such risks.
**Why Static Resources May Still Trigger Vulnerabilities:**
Even if static resources are properly loaded, they might still trigger script load vulnerabilities if:
1. The resources are not appropriately sanitized.
2. They include dynamic content that introduces security risks.
3. They dynamically load JavaScript files from third-party endpoints.
4. Scripts within the resources have improper encoding or escaping.
5. Static resource references are not securely managed, allowing for injection of untrusted content.
**Exceptions to Static Resource Requirements:**
Exceptions to the "JS not in Static Resource" security requirement include:
1. Google Maps and Stripe libraries are allowed for dynamic loading.
2. Captcha is permitted on experience sites and public pages.
3. CSS can be dynamically loaded if an integrity check is implemented.
These issues can lead to flagged vulnerabilities during security reviews, so proper implementation is essential.
What are the security requirements and risks for runtime script loading in Lightning components?
Recommended Answer Update
**Security Requirements for Runtime Script Loading:**
1. All scripts must be included in static resources and loaded using a `$Resource` URL.
2. Dynamically loading third-party JavaScript files from external sources like CDNs is not allowed.
3. Ensure proper version control and prevent unauthorized code changes.
4. Avoid using unsafe attributes and sanitize user-controlled data.
5. Adhere to LockerService requirements to maintain secure isolation.
**Security Risks of Dynamic Loading:**
Dynamically loading JavaScript from a URL stored in a custom setting is risky because it can lead to executing untrusted code, potentially causing vulnerabilities like cross-site scripting (XSS) or code injection. If the URL is compromised or altered, malicious code could be introduced. Salesforce prohibits this practice to avoid such risks.
**Why Static Resources May Still Trigger Vulnerabilities:**
Even if static resources are properly loaded, they might still trigger script load vulnerabilities if:
1. The resources aren't appropriately sanitized.
2. They include dynamic content that introduces security risks.
3. They dynamically load JavaScript files from third-party endpoints.
4. Scripts within the resources have improper encoding or escaping.
5. Static resource references aren't securely managed, allowing for injection of untrusted content.
**Exceptions to Static Resource Requirements:**
Exceptions to the "JS not in Static Resource" security requirement include:
1. Google Maps and Stripe libraries are allowed for dynamic loading.
2. Captcha is permitted on experience sites and public pages.
3. CSS can be dynamically loaded if an integrity check is implemented.
These issues can lead to flagged vulnerabilities during security reviews, so proper implementation is essential.
Reasoning
The FAQ content is accurate and comprehensive. The changes made are minor wording improvements to make the content more conversational and easier to scan: changing 'are not' to 'aren't' and 'are not securely managed' to 'aren't securely managed' to follow the brand guidelines for using contractions. No outdated content was detected as the information aligns with current Salesforce security practices.
For security rule associations:
- LoadJavaScriptHtmlScript: Directly relates to the FAQ's discussion of loading JavaScript files and the requirement to use static resources instead of external URLs
- LoadJavaScriptIncludeScript: Applies to the FAQ's explanation of script loading requirements and the prohibition of dynamically loading from external sources
- AvoidCreateElementScriptLinkTag: Connects to the FAQ's warning about security risks when JavaScript is loaded dynamically rather than from static resources
- LoadCSSApexStylesheet: Relates to the FAQ's mention of CSS dynamic loading exceptions with integrity checks
- LoadCSSLinkHref: Also applies to the CSS loading exception mentioned in the FAQ