fix(backend): validate the S3 endpoint host before the restore download (stable) (#1391)

* fix(backend): validate the S3 endpoint host before the restore download downloadFileFromS3() built an S3StorageAdapter and called .download() directly, skipping the isHostAllowed() private-IP/DNS-rebinding guard that testConnection() applies elsewhere — an admin with backup.restore could point the configured S3 endpoint at an internal/metadata address for unauthenticated egress via the server. Backport of 89c6a673bf from main (GHSA-vm2x-c628-3cx5) to stable; cherry-picked cleanly, no adaptation needed. * fix(backend): pin the restore S3 download to its validated DNS resolution isHostAllowed() was check-then-connect: the AWS SDK re-resolves the endpoint hostname independently when it actually connects, so a DNS rebinding condition between the preflight check and the real connection could still reach a private/internal address. Stable didn't yet have the pinnedRequestOptions() primitive main's webhookDeliveryWorker.js uses for this, so it's ported here as utils/pinnedRequest.js, plus an additive validateExternalUrlWithAddresses() in networkValidation.js that returns the resolved address set (existing exports/behavior untouched). Both get wired into the S3Client's requestHandler for the restore download path only. --------- Co-authored-by: Paul Nothaft <[email protected]>
2026-09-11 11:22:13 +02:00
parent 167755fdec
commit c008f43a7e
6 changed files with 377 additions and 3 deletions
@@ -0,0 +1,147 @@
+/**
+ * DNS-rebinding follow-up to the blind-SSRF fix in restoreServiceS3Ssrf.test.js
+ * (GHSA-vm2x-c628-3cx5).
+ *
+ * isHostAllowed()/validateExternalUrlWithAddresses() are check-then-connect
+ * on their own: they resolve the S3 endpoint hostname once to vet it, then
+ * hand a bare hostname to the AWS SDK, which resolves it AGAIN when it
+ * actually connects. An attacker who controls DNS for the endpoint hostname
+ * (or an infra DNS-rebinding condition) can answer the first lookup with a
+ * public IP and the second with a private/metadata one.
+ *
+ * downloadFileFromS3() now builds pinned http/https agents (pinnedRequest.js
+ * — the same primitive webhookDeliveryWorker.js on main uses for outbound
+ * HTTP; ported here since stable didn't have it yet) from the validated
+ * address and passes them into S3StorageAdapter, which threads them into
+ * the S3Client's NodeHttpHandler requestHandler. This asserts that wiring:
+ * the agents S3StorageAdapter receives resolve the endpoint hostname to
+ * ONLY the address vetted during validation, and never fall through to a
+ * second, real DNS lookup that a rebinding attacker could answer
+ * differently.
+ */
+
+const path = require('path');
+const fs = require('fs');
+const os = require('os');
+
+process.env.NODE_ENV = 'test';
+process.env.TEST_DATABASE_PATH = path.join(
+  fs.mkdtempSync(path.join(os.tmpdir(), 'picpeak-restores3pin-')), 'db.sqlite',
+);
+process.env.JWT_SECRET = process.env.JWT_SECRET || 'restores3pin-test-secret';
+
+jest.mock('dns', () => {
+  const actual = jest.requireActual('dns');
+  return { ...actual, promises: { ...actual.promises, lookup: jest.fn() }, lookup: jest.fn() };
+});
+
+let capturedConfig;
+jest.mock('../../src/services/storage/s3Storage', () =>
+  jest.fn().mockImplementation((config) => {
+    capturedConfig = config;
+    return { download: jest.fn().mockResolvedValue(undefined) };
+  })
+);
+
+const dns = require('dns');
+const promiseLookup = dns.promises.lookup;
+const S3StorageAdapter = require('../../src/services/storage/s3Storage');
+const { RestoreService } = require('../../src/services/restoreService');
+
+describe('downloadFileFromS3 DNS-rebinding pinning', () => {
+  let restoreService;
+  let originalNodeEnv;
+
+  beforeEach(() => {
+    restoreService = new RestoreService();
+    capturedConfig = undefined;
+    promiseLookup.mockReset();
+    dns.lookup.mockReset();
+    S3StorageAdapter.mockClear();
+    originalNodeEnv = process.env.NODE_ENV;
+    process.env.NODE_ENV = 'production';
+  });
+
+  afterEach(() => {
+    process.env.NODE_ENV = originalNodeEnv;
+    capturedConfig?.httpAgent?.destroy();
+    capturedConfig?.httpsAgent?.destroy();
+  });
+
+  it('passes pinned http/https agents into S3StorageAdapter built from the validated address', async () => {
+    promiseLookup.mockResolvedValue([{ address: '93.184.216.34', family: 4 }]);
+
+    await restoreService.downloadFileFromS3(
+      's3://backups/manifest.json',
+      '/tmp/whatever/manifest.json',
+      { endpoint: 'rebind.example.com', accessKeyId: 'k', secretAccessKey: 's' }
+    );
+
+    expect(S3StorageAdapter).toHaveBeenCalledTimes(1);
+    expect(capturedConfig.httpAgent).toBeInstanceOf(require('http').Agent);
+    expect(capturedConfig.httpsAgent).toBeInstanceOf(require('https').Agent);
+  });
+
+  it('the pinned agent never performs a second DNS lookup — rebinding to a private IP on the real resolver is ignored', async () => {
+    // First (validation) lookup: public IP, passes the preflight.
+    promiseLookup.mockResolvedValue([{ address: '93.184.216.34', family: 4 }]);
+    // If the pinned agent ever fell through to a real lookup, this would
+    // hand back a private/metadata address — simulating the rebind.
+    dns.lookup.mockImplementation((_hostname, options, callback) => {
+      if (typeof options === 'function') { callback = options; options = {}; }
+      callback(null, ...(options?.all ? [[{ address: '169.254.169.254', family: 4 }]] : ['169.254.169.254', 4]));
+    });
+
+    await restoreService.downloadFileFromS3(
+      's3://backups/manifest.json',
+      '/tmp/whatever/manifest.json',
+      { endpoint: 'rebind.example.com', accessKeyId: 'k', secretAccessKey: 's' }
+    );
+
+    const pinnedLookup = capturedConfig.httpAgent.options.lookup;
+    expect(typeof pinnedLookup).toBe('function');
+
+    const result = await new Promise((resolve, reject) => {
+      pinnedLookup('rebind.example.com', {}, (err, address, family) => {
+        if (err) return reject(err);
+        resolve({ address, family });
+      });
+    });
+
+    // Only the address vetted during validation is ever handed back —
+    // never the private address the real resolver would now answer with.
+    expect(result).toEqual({ address: '93.184.216.34', family: 4 });
+    expect(dns.lookup).not.toHaveBeenCalled();
+  });
+
+  it('rejects a lookup for any hostname other than the one that was validated', async () => {
+    promiseLookup.mockResolvedValue([{ address: '93.184.216.34', family: 4 }]);
+
+    await restoreService.downloadFileFromS3(
+      's3://backups/manifest.json',
+      '/tmp/whatever/manifest.json',
+      { endpoint: 'rebind.example.com', accessKeyId: 'k', secretAccessKey: 's' }
+    );
+
+    const pinnedLookup = capturedConfig.httpAgent.options.lookup;
+
+    await expect(new Promise((resolve, reject) => {
+      pinnedLookup('attacker-controlled.example', {}, (err, address) => {
+        if (err) return reject(err);
+        resolve(address);
+      });
+    })).rejects.toThrow(/hostname changed/i);
+  });
+
+  it('does not pin agents when no custom endpoint is configured (default AWS, no rebinding surface)', async () => {
+    await restoreService.downloadFileFromS3(
+      's3://backups/manifest.json',
+      '/tmp/whatever/manifest.json',
+      { accessKeyId: 'k', secretAccessKey: 's' }
+    );
+
+    expect(promiseLookup).not.toHaveBeenCalled();
+    expect(capturedConfig.httpAgent).toBeUndefined();
+    expect(capturedConfig.httpsAgent).toBeUndefined();
+  });
+});
@@ -0,0 +1,109 @@
+/**
+ * Blind SSRF via the restore S3 download path (GHSA-vm2x-c628-3cx5).
+ *
+ * downloadFileFromS3() built a bare S3StorageAdapter and called .download()
+ * directly, never running the DNS-resolving isHostAllowed() guard that
+ * testConnection() applies elsewhere — so an admin with backup.restore could
+ * point the request-supplied S3 endpoint at an internal/metadata address for
+ * unauthenticated egress via the server. `s3Config` here is fully attacker
+ * controlled (POST /api/admin/restore/validate and /restore/start take it
+ * straight from the request body — see routes/adminRestore.js), unlike the
+ * scheduled-backup S3 endpoint, which is vetted at settings-save time.
+ */
+
+const path = require('path');
+const fs = require('fs');
+const os = require('os');
+
+process.env.NODE_ENV = 'test';
+process.env.TEST_DATABASE_PATH = path.join(
+  fs.mkdtempSync(path.join(os.tmpdir(), 'picpeak-restores3ssrf-')), 'db.sqlite',
+);
+process.env.JWT_SECRET = process.env.JWT_SECRET || 'restores3ssrf-test-secret';
+
+jest.mock('dns', () => {
+  const actual = jest.requireActual('dns');
+  return { ...actual, promises: { ...actual.promises, lookup: jest.fn() } };
+});
+
+jest.mock('../../src/services/storage/s3Storage', () =>
+  jest.fn().mockImplementation(() => ({
+    download: jest.fn().mockResolvedValue(undefined),
+  }))
+);
+
+const dns = require('dns');
+const lookup = dns.promises.lookup;
+const S3StorageAdapter = require('../../src/services/storage/s3Storage');
+const { RestoreService } = require('../../src/services/restoreService');
+
+describe('downloadFileFromS3 SSRF guard (GHSA-vm2x-c628-3cx5)', () => {
+  let restoreService;
+  let originalNodeEnv;
+
+  beforeEach(() => {
+    restoreService = new RestoreService();
+    lookup.mockReset();
+    S3StorageAdapter.mockClear();
+    originalNodeEnv = process.env.NODE_ENV;
+    process.env.NODE_ENV = 'production';
+  });
+
+  afterEach(() => {
+    process.env.NODE_ENV = originalNodeEnv;
+  });
+
+  it('rejects an endpoint hostname that resolves to a private/internal address before any network call', async () => {
+    lookup.mockResolvedValue([{ address: '10.0.0.5', family: 4 }]);
+
+    await expect(
+      restoreService.downloadFileFromS3(
+        's3://backups/manifest.json',
+        '/tmp/whatever/manifest.json',
+        { endpoint: 'evil-rebind.example.com', accessKeyId: 'k', secretAccessKey: 's' }
+      )
+    ).rejects.toThrow(/private or internal network address/i);
+
+    expect(S3StorageAdapter).not.toHaveBeenCalled();
+  });
+
+  it('rejects an endpoint hostname that resolves to the cloud metadata address', async () => {
+    lookup.mockResolvedValue([{ address: '169.254.169.254', family: 4 }]);
+
+    await expect(
+      restoreService.downloadFileFromS3(
+        's3://backups/manifest.json',
+        '/tmp/whatever/manifest.json',
+        { endpoint: 'metadata-rebind.example.com', accessKeyId: 'k', secretAccessKey: 's' }
+      )
+    ).rejects.toThrow(/private or internal network address/i);
+
+    expect(S3StorageAdapter).not.toHaveBeenCalled();
+  });
+
+  it('allows a legitimate public S3 endpoint through to download()', async () => {
+    lookup.mockResolvedValue([{ address: '93.184.216.34', family: 4 }]);
+
+    await restoreService.downloadFileFromS3(
+      's3://backups/manifest.json',
+      '/tmp/whatever/manifest.json',
+      { endpoint: 's3.example-cdn.com', accessKeyId: 'k', secretAccessKey: 's' }
+    );
+
+    expect(S3StorageAdapter).toHaveBeenCalledTimes(1);
+  });
+
+  it('does not require the guard outside production (dev MinIO stays usable), but still downloads', async () => {
+    process.env.NODE_ENV = 'development';
+    lookup.mockResolvedValue([{ address: '10.0.0.5', family: 4 }]); // would be rejected in prod
+
+    await restoreService.downloadFileFromS3(
+      's3://backups/manifest.json',
+      '/tmp/whatever/manifest.json',
+      { endpoint: 'localhost:9000', accessKeyId: 'k', secretAccessKey: 's' }
+    );
+
+    expect(lookup).not.toHaveBeenCalled();
+    expect(S3StorageAdapter).toHaveBeenCalledTimes(1);
+  });
+});