XSS Protection — SiteSentinel

What This Check Measures

This check evaluates protection against Cross-Site Scripting (XSS) attacks — where attackers inject malicious scripts into web pages viewed by other users.

Why It Matters

Session Hijacking — Attackers can steal user session cookies
Credential Theft — Fake login forms can capture passwords
Malware Distribution — Injected scripts can redirect to malicious sites
Defacement — Page content can be modified for visitors
Keylogging — User keystrokes can be captured

How Data Is Obtained

Source File

src/checks/safety.check.js

Function

SafetyCheck.analyze(url)

Current Implementation

// References the Security section for CSP header analysis
checks.push({
  name: 'XSS (Cross-Site Scripting) Protection',
  status: 'info',
  description: 'CSP headers provide XSS protection (see Security section)',
  severity: 'high'
});

Related Check

For actual XSS protection analysis, see the Security Headers Agent (security.check.js) which examines:

Content-Security-Policy (CSP) header
X-XSS-Protection header (deprecated but still checked)
X-Content-Type-Options header

Status Values

Status	Meaning
info	This check is informational. XSS protection is primarily evaluated through CSP headers in the Security section.

Severity: High

This check has high severity because:

XSS attacks can compromise user accounts
They're common and often automated
Impact ranges from annoyance to complete account takeover
They can be used as stepping stones for larger attacks

Types of XSS Attacks

Stored XSS

Malicious script is permanently stored on the target server (e.g., in a database). Affects all users who view the infected content.

Reflected XSS

Script is reflected off a web server in error messages, search results, or URL parameters. Requires user to click a malicious link.

DOM-based XSS

Vulnerability exists in client-side JavaScript that processes user input unsafely. Server never sees the malicious payload.

Protection Mechanisms

How to Protect Against XSS

Content Security Policy (CSP) — Restrict script sources via HTTP header
Output Encoding — Escape user input when rendering HTML
Input Validation — Sanitize and validate all user inputs
HTTPOnly Cookies — Prevent JavaScript access to session cookies
X-Content-Type-Options — Prevent MIME type sniffing
Modern Frameworks — Use frameworks with built-in XSS protection (React, Vue, Angular)

Impact on Category Score

Currently returns info status with neutral impact. For XSS protection scoring, the Security Headers Agent evaluates CSP and other protective headers.