From e2e189eedef5b38f664a3dfb2fc95e2de3ddb433 Mon Sep 17 00:00:00 2001
From: Saravana Achu Mac <saravanakumardb1@gmail.com>
Date: Mon, 4 May 2026 17:07:52 -0700
Subject: [PATCH] fix(C7): mitigate FMP key exposure

---
 README.md                        |  5 +++++
 backend/src/services/fmpCache.ts | 31 +++++++++++++++++++++++++------
 backend/testFmpCache.ts          | 11 +++++++++++
 3 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 8d25e47..acbe628 100644
--- a/README.md
+++ b/README.md
@@ -132,6 +132,11 @@ Each surface has its own `.env.example`. The root `.env.example` is the comprehe
 | `PAPER_TRADING` | — | Set `true` for paper mode |
 | `AZURE_KEYVAULT_URL` | Prod | Enables auto-resolution of `invttrdg-*` secrets at startup |
 
+Financial Modeling Prep requires `apikey` query-string authentication, so the
+backend keeps all FMP calls server-side, rejects the shared `demo` key, caches
+FMP responses for 30 minutes, hashes cache keys instead of storing raw URLs, and
+uses redacted URL helpers for any future FMP log output.
+
 ## Shared Dependencies
 
 Common-platform packages are vendored from `../learning_ai_common_plat/packages/*`
diff --git a/backend/src/services/fmpCache.ts b/backend/src/services/fmpCache.ts
index ad5a93f..e7c2a06 100644
--- a/backend/src/services/fmpCache.ts
+++ b/backend/src/services/fmpCache.ts
@@ -1,3 +1,5 @@
+import { createHash } from 'node:crypto';
+
 export const FMP_CACHE_TTL_MS = 30 * 60 * 1000;
 
 export class FmpFetchError extends Error {
@@ -23,8 +25,25 @@ const inFlightFmpRequests = new Map<string, Promise<unknown>>();
 
 let now = () => Date.now();
 
+export function redactFmpUrlForLogs(url: string): string {
+    try {
+        const parsed = new URL(url);
+        if (parsed.searchParams.has('apikey')) {
+            parsed.searchParams.set('apikey', '[REDACTED]');
+        }
+        return parsed.toString();
+    } catch {
+        return url.replace(/([?&]apikey=)[^&]+/i, '$1[REDACTED]');
+    }
+}
+
+export function buildFmpCacheKey(url: string): string {
+    return createHash('sha256').update(url).digest('hex');
+}
+
 export async function fetchFmpJson(url: string, fetchJson: FetchJson = fetch): Promise<unknown> {
-    const cached = fmpCache.get(url);
+    const cacheKey = buildFmpCacheKey(url);
+    const cached = fmpCache.get(cacheKey);
     const currentTime = now();
 
     if (cached && cached.expiresAt > currentTime) {
@@ -32,10 +51,10 @@ export async function fetchFmpJson(url: string, fetchJson: FetchJson = fetch): P
     }
 
     if (cached) {
-        fmpCache.delete(url);
+        fmpCache.delete(cacheKey);
     }
 
-    const inFlight = inFlightFmpRequests.get(url);
+    const inFlight = inFlightFmpRequests.get(cacheKey);
     if (inFlight) {
         return inFlight;
     }
@@ -47,17 +66,17 @@ export async function fetchFmpJson(url: string, fetchJson: FetchJson = fetch): P
             }
 
             const data = await response.json();
-            fmpCache.set(url, {
+            fmpCache.set(cacheKey, {
                 data,
                 expiresAt: now() + FMP_CACHE_TTL_MS,
             });
             return data;
         })
         .finally(() => {
-            inFlightFmpRequests.delete(url);
+            inFlightFmpRequests.delete(cacheKey);
         });
 
-    inFlightFmpRequests.set(url, request);
+    inFlightFmpRequests.set(cacheKey, request);
     return request;
 }
 
diff --git a/backend/testFmpCache.ts b/backend/testFmpCache.ts
index 9abe179..f257ecf 100644
--- a/backend/testFmpCache.ts
+++ b/backend/testFmpCache.ts
@@ -1,9 +1,11 @@
 import assert from 'node:assert/strict';
 import {
+    buildFmpCacheKey,
     clearFmpCacheForTests,
     fetchFmpJson,
     FMP_CACHE_TTL_MS,
     FmpFetchError,
+    redactFmpUrlForLogs,
     setFmpCacheNowForTests,
 } from './src/services/fmpCache.js';
 
@@ -42,6 +44,15 @@ async function main() {
     const otherUrl = 'https://financialmodelingprep.com/api/v3/profile/MSFT?apikey=test';
     const fetcher = createFetch([{ symbol: 'AAPL' }, { symbol: 'AAPL-refresh' }]);
 
+    const cacheKey = buildFmpCacheKey(url);
+    assert.notEqual(cacheKey, url, 'cache keys should not retain raw FMP URLs with query-string API keys');
+    assert(!cacheKey.includes('apikey'), 'cache keys should not expose the FMP apikey parameter');
+    assert.equal(
+        redactFmpUrlForLogs(url),
+        'https://financialmodelingprep.com/api/v3/profile/AAPL?apikey=%5BREDACTED%5D',
+        'log-safe FMP URLs should redact apikey values',
+    );
+
     assert.deepEqual(await fetchFmpJson(url, fetcher.fetchJson), { symbol: 'AAPL' });
     assert.deepEqual(await fetchFmpJson(url, fetcher.fetchJson), { symbol: 'AAPL' });
     assert.equal(fetcher.calls, 1, 'same full URL should be served from cache before TTL expiry');