microsoft
diff --git a/‎.github/issue-assistant/src/security.js‎
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+/**
+ * Security Validation Module for MSDO Issue Assistant
+ * 
+ * SECURITY DESIGN:
+ * - Core detection logic is in code (open source)
+ * - Specific patterns can be overridden via GitHub Secrets (hidden)
+ * - This prevents attackers from seeing exact patterns to bypass
+ * 
+ * Pattern sources (in priority order):
+ * 1. GitHub Secrets (if provided) - hidden from attackers
+ * 2. Built-in patterns (visible in code) - baseline protection
+ */
+
+// Built-in patterns - provides baseline protection
+// Additional/custom patterns can be stored in GitHub Secrets
+const DEFAULT_INJECTION_PATTERNS = [
+  /ignore\s+(all\s+)?(previous|prior)/i,
+  /disregard\s+(your\s+)?instructions/i,
+  /you\s+are\s+now/i,
+  /pretend\s+(to\s+be|you)/i,
+  /system\s*prompt/i,
+  /jailbreak/i,
+  /<\|.*\|>/i,
+  /\[\[.*\]\]/i,
+];
+
+const DEFAULT_SUSPICIOUS_PATTERNS = [
+  /\@(dependabot|github-actions)/i,
+  /merge\s+this/i,
+  /webhook/i,
+];
+
+function compilePatterns(secretPatterns, defaultPatterns) {
+  if (secretPatterns && Array.isArray(secretPatterns)) {
+    return secretPatterns.map(p => {
+      if (typeof p === 'string') {
+        const match = p.match(/^\/(.*)\/([gimsuy]*)$/);
+        if (match) {
+          const safeFlags = match[2].replace(/[gy]/g, '');
+          return new RegExp(match[1], safeFlags);
+        }
+        return new RegExp(p, 'i');
+      }
+      if (p instanceof RegExp) {
+        const safeFlags = p.flags.replace(/[gy]/g, '');
+        return new RegExp(p.source, safeFlags);
+      }
+      return p;
+    });
+  }
+  return defaultPatterns;
+}
+
+function detectPromptInjection(content, customPatterns) {
+  const patterns = compilePatterns(customPatterns, DEFAULT_INJECTION_PATTERNS);
+  const normalizedContent = content
+    .replace(/\s+/g, ' ')
+    .replace(/[^\x20-\x7E\s]/g, ' ');
+  
+  const detected = [];
+  for (const pattern of patterns) {
+    if (pattern.test(normalizedContent)) {
+      detected.push('pattern_match');
+    }
+  }
+  
+  return {
+    detected: detected.length > 0,
+    count: detected.length
+  };
+}
+
+function detectSuspiciousContent(content, customPatterns) {
+  const patterns = compilePatterns(customPatterns, DEFAULT_SUSPICIOUS_PATTERNS);
+  const detected = [];
+  
+  for (const pattern of patterns) {
+    if (pattern.test(content)) {
+      detected.push('suspicious_match');
+    }
+  }
+  
+  const words = content.toLowerCase().split(/\s+/);
+  const wordCounts = {};
+  for (const word of words) {
+    wordCounts[word] = (wordCounts[word] || 0) + 1;
+  }
+  const maxRepetition = Math.max(...Object.values(wordCounts), 0);
+  if (maxRepetition > 50) {
+    detected.push('excessive_repetition');
+  }
+  
+  return {
+    detected: detected.length > 0,
+    count: detected.length
+  };
+}
+
+async function checkRateLimit(github, context, userId, limitPerHour) {
+  const oneHourAgo = new Date(Date.now() - 60 * 60 * 1000).toISOString();
+  
+  try {
+    let responseCount = 0;
+    let page = 1;
+    const perPage = 100;
+    
+    while (true) {
+      const { data: comments } = await github.rest.issues.listCommentsForRepo({
+        owner: context.repo.owner,
+        repo: context.repo.repo,
+        since: oneHourAgo,
+        per_page: perPage,
+        page: page
+      });
+      
+      if (comments.length === 0) break;
+      
+      for (const comment of comments) {
+        if (comment.body && comment.body.includes('<!-- msdo-issue-assistant -->')) {
+          try {
+            const { data: issue } = await github.rest.issues.get({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: comment.issue_url.split('/').pop()
+            });
+            
+            if (issue.user && issue.user.id === userId) {
+              responseCount++;
+            }
+          } catch (e) {
+            responseCount++;
+          }
+        }
+      }
+      
+      if (comments.length < perPage) break;
+      page++;
+      
+      if (page > 10) break;
+    }
+    
+    return {
+      allowed: responseCount < limitPerHour,
+      currentCount: responseCount
+    };
+  } catch (error) {
+    console.error('Rate limit check failed:', error.message);
+    return { allowed: false, error: error.message };
+  }
+}
+
+function sanitizeInput(content, maxLength) {
+  if (!content) return '';
+  
+  let sanitized = content
+    .replace(/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/g, '')
+    .replace(/[^\S\r\n]+/g, ' ')
+    .replace(/\n{3,}/g, '\n\n')
+    .trim();
+  
+  if (sanitized.length > maxLength) {
+    sanitized = sanitized.substring(0, maxLength) + '... [truncated]';
+  }
+  
+  return sanitized;
+}
+
+function detectIssueType(title, body) {
+  const content = (title + ' ' + body).toLowerCase();
+  
+  const bugScore = ['bug', 'error', 'fail', 'crash', 'broken', 'not working'].filter(w => content.includes(w)).length;
+  const featureScore = ['feature', 'request', 'enhancement', 'suggestion', 'add support'].filter(w => content.includes(w)).length;
+  const questionScore = ['how to', 'how do', 'question', 'help', 'possible'].filter(w => content.includes(w)).length;
+  
+  if (bugScore === 0 && featureScore === 0 && questionScore === 0) return 'unknown';
+  if (bugScore >= featureScore && bugScore >= questionScore) return 'bug';
+  if (featureScore >= questionScore) return 'feature';
+  return 'question';
+}
+
+async function validateRequest({ 
+  github, 
+  context, 
+  maxInputLength, 
+  rateLimitPerHour,
+  customInjectionPatterns,
+  customSuspiciousPatterns
+}) {
+  const errors = [];
+  const issue = context.payload.issue;
+  const comment = context.payload.comment;
+  
+  const content = comment ? comment.body : issue.body;
+  const title = issue.title || '';
+  const userId = comment ? comment.user.login : issue.user.login;
+  const userIdNum = comment ? comment.user.id : issue.user.id;
+  const userType = comment ? comment.user.type : issue.user.type;
+  
+  if (userType === 'Bot') {
+    errors.push('Bot users not processed');
+    return { shouldRespond: false, errors };
+  }
+  
+  if (!content || content.length === 0) {
+    errors.push('Empty content');
+    return { shouldRespond: false, errors };
+  }
+  
+  if (content.length > maxInputLength) {
+    errors.push('Content exceeds maximum length');
+  }
+  
+  const injectionCheck = detectPromptInjection(content, customInjectionPatterns);
+  if (injectionCheck.detected) {
+    errors.push('Potential prompt injection detected');
+    console.log('Injection attempt from ' + userId + ': ' + injectionCheck.count + ' patterns matched');
+  }
+  
+  const suspiciousCheck = detectSuspiciousContent(content, customSuspiciousPatterns);
+  if (suspiciousCheck.detected) {
+    errors.push('Suspicious content detected');
+  }
+  
+  const rateLimit = await checkRateLimit(github, context, userIdNum, rateLimitPerHour);
+  if (!rateLimit.allowed) {
+    errors.push('Rate limit exceeded');
+  }
+  
+  if (comment) {
+    const { data: comments } = await github.rest.issues.listComments({
+      owner: context.repo.owner,
+      repo: context.repo.repo,
+      issue_number: issue.number
+    });
+    
+    const botComments = comments.filter(c => 
+      c.body && c.body.includes('<!-- msdo-issue-assistant -->')
+    );
+    
+    if (botComments.length >= 3) {
+      errors.push('Maximum bot responses reached');
+    }
+  }
+  
+  return {
+    shouldRespond: errors.length === 0,
+    errors,
+    sanitizedContent: sanitizeInput(content, maxInputLength),
+    issueType: detectIssueType(title, content)
+  };
+}
+
+module.exports = {
+  validateRequest,
+  detectPromptInjection,
+  detectSuspiciousContent,
+  sanitizeInput,
+  detectIssueType,
+  checkRateLimit
+};