fix(federation): security hardening — OID verification, atomic activation, audit on failure (#501)

apps/gateway/src/federation/ca.service.ts

@@ -35,7 +35,7 @@ import * as crypto from 'node:crypto';
 import * as fs from 'node:fs';
 import * as https from 'node:https';
 import { SignJWT, importJWK } from 'jose';
-import { Pkcs10CertificateRequest } from '@peculiar/x509';
+import { Pkcs10CertificateRequest, X509Certificate } from '@peculiar/x509';
 import type { IssueCertRequestDto } from './ca.dto.js';
 import { IssuedCertDto } from './ca.dto.js';
 
@@ -624,6 +624,51 @@ export class CaService {
 
     const serialNumber = extractSerial(response.crt);
 
+    // CRIT-1: Verify the issued certificate contains both Mosaic OID extensions
+    // with the correct values. Step-CA's federation.tpl encodes each as an ASN.1
+    // UTF8String TLV: tag 0x0C + 1-byte length + UUID bytes. We skip 2 bytes
+    // (tag + length) to extract the raw UUID string.
+    const issuedCert = new X509Certificate(response.crt);
+    const decoder = new TextDecoder();
+
+    const grantIdExt = issuedCert.getExtension('1.3.6.1.4.1.99999.1');
+    if (!grantIdExt) {
+      throw new CaServiceError(
+        'Issued certificate is missing required Mosaic OID: mosaic_grant_id',
+        'The Step-CA federation.tpl template did not embed OID 1.3.6.1.4.1.99999.1. Check the provisioner template configuration.',
+        undefined,
+        'OID_MISSING',
+      );
+    }
+    const grantIdInCert = decoder.decode(grantIdExt.value.slice(2));
+    if (grantIdInCert !== req.grantId) {
+      throw new CaServiceError(
+        `Issued certificate mosaic_grant_id mismatch: expected ${req.grantId}, got ${grantIdInCert}`,
+        'The Step-CA issued a certificate with a different grant ID than requested. This may indicate a provisioner misconfiguration or a MITM.',
+        undefined,
+        'OID_MISMATCH',
+      );
+    }
+
+    const subjectUserIdExt = issuedCert.getExtension('1.3.6.1.4.1.99999.2');
+    if (!subjectUserIdExt) {
+      throw new CaServiceError(
+        'Issued certificate is missing required Mosaic OID: mosaic_subject_user_id',
+        'The Step-CA federation.tpl template did not embed OID 1.3.6.1.4.1.99999.2. Check the provisioner template configuration.',
+        undefined,
+        'OID_MISSING',
+      );
+    }
+    const subjectUserIdInCert = decoder.decode(subjectUserIdExt.value.slice(2));
+    if (subjectUserIdInCert !== req.subjectUserId) {
+      throw new CaServiceError(
+        `Issued certificate mosaic_subject_user_id mismatch: expected ${req.subjectUserId}, got ${subjectUserIdInCert}`,
+        'The Step-CA issued a certificate with a different subject user ID than requested. This may indicate a provisioner misconfiguration or a MITM.',
+        undefined,
+        'OID_MISMATCH',
+      );
+    }
+
     this.logger.log(`Certificate issued — serial=${serialNumber} grantId=${req.grantId}`);
 
     const result = new IssuedCertDto();