Glean security basics

Glean Security Basics

Overview

Glean indexes and searches across an enterprise's entire knowledge base — Confluence, Google Drive, Slack, GitHub, and dozens more connectors. Security concerns center on indexing token management (write-access tokens that can push content into the search index), client token scoping (user-level search permissions), and document-level access controls. A leaked indexing token allows injecting arbitrary content into enterprise search results.

API Key Management

function createGleanClient(tokenType: "indexing" | "client"): { token: string; baseUrl: string } {
  const token = tokenType === "indexing"
    ? process.env.GLEAN_INDEXING_TOKEN
    : process.env.GLEAN_CLIENT_TOKEN;
  if (!token) {
    throw new Error(`Missing GLEAN_${tokenType.toUpperCase()}_TOKEN — store in secrets manager`);
  }
  // Indexing tokens have WRITE access — never expose in frontend code
  if (tokenType === "indexing") {
    console.log("WARNING: Indexing token loaded — backend use only");
  }
  return { token, baseUrl: `https://${process.env.GLEAN_INSTANCE}.glean.com/api` };
}

Webhook Signature Verification

import crypto from "crypto";
import { Request, Response, NextFunction } from "express";

function verifyGleanWebhook(req: Request, res: Response, next: NextFunction): void {
  const signature = req.headers["x-glean-signature"] as string;
  const secret = process.env.GLEAN_WEBHOOK_SECRET!;
  const expected = crypto.createHmac("sha256", secret).update(req.body).digest("hex");
  if (!signature || !crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(expected))) {
    res.status(401).send("Invalid signature");
    return;
  }
  next();
}

Input Validation

import { z } from "zod";

const IndexDocumentSchema = z.object({
  datasource: z.string().min(1).max(100),
  document_id: z.string().min(1).max(500),
  title: z.string().min(1).max(500),
  body: z.string().max(1_000_000),
  allowed_users: z.array(z.string().email()).optional(),
  allowed_groups: z.array(z.string()).optional(),
  permissions_type: z.enum(["public", "restricted", "private"]).default("restricted"),
});

function validateIndexDocument(data: unknown) {
  return IndexDocumentSchema.parse(data);
}

Data Protection

const GLEAN_SENSITIVE_FIELDS = ["indexing_token", "client_token", "document_body", "user_query", "search_results"];

function redactGleanLog(record: Record<string, unknown>): Record<string, unknown> {
  const redacted = { ...record };
  for (const field of GLEAN_SENSITIVE_FIELDS) {
    if (field in redacted) redacted[field] = "[REDACTED]";
  }
  return redacted;
}

Security Checklist

• Indexing tokens stored server-side only, never in frontend code
• Client tokens scoped per-user with X-Glean-Auth-Type header
• Tokens rotated quarterly via Admin > API Tokens
• Document permissions set via allowedUsers/allowedGroups
• SAML SSO enforced for Glean web access
• All API calls over HTTPS
• Search audit logs enabled to track sensitive queries
• Connector permissions reviewed when adding new data sources

Error Handling

Vulnerability	Risk	Mitigation
Leaked indexing token	Arbitrary content injected into search index	Backend-only storage + rotation
Missing document permissions	Confidential docs exposed in search results	allowedUsers/allowedGroups on every document
Client token in frontend	User impersonation in search queries	Server-side proxy for search API
Overly broad connector scope	Sensitive repos/channels indexed unintentionally	Per-connector permission review
Search queries in logs	Employee activity surveillance risk	Query redaction in logging pipeline

Resources

• Glean Developer Portal
• OWASP API Security Top 10

Next Steps

See glean-prod-checklist.