TIS1702 - Gateway’s TLS Configuration Does Not Comply with FIPS 140-2 Requirements

The gateway’s TLS configuration (versions or cipher suites) does not meet strict FIPS 140-2 requirements. FIPS-compliant configurations must restrict the TLS protocol to version 1.2 and limit the cipher suites to the four ECDHE-based AES-GCM suites approved under FIPS 140-2.

Recommendation: Adjust Gateway TLS Configuration for Strict FIPS

By ensuring that your gateway’s TLS settings use only TLS 1.2 and the four ECDHE AES-GCM cipher suites, you can maintain strict FIPS compliance for inbound connections to your service mesh.

Examples

1. Gateway Config Allowing TLS 1.3

   apiVersion: networking.istio.io/v1alpha3
   kind: Gateway
   metadata:
     name: non-fips-gateway
   spec:
     selector:
       istio: ingressgateway
     servers:
     - port:
         number: 443
         name: https
         protocol: HTTPS
       hosts:
         - "*"
       tls:
         mode: SIMPLE
         # minProtocolVersion is TLSv1_2, but maxProtocolVersion is TLSv1_3.
         minProtocolVersion: TLSV1_2
         maxProtocolVersion: TLSV1_3
         cipherSuites:
           - ECDHE-RSA-AES128-GCM-SHA256
           - ECDHE-RSA-AES256-GCM-SHA384

   Explanation: Although TLS 1.2 is allowed, TLS 1.3 is also enabled, which violates strict FIPS 140-2 restrictions. FIPS 140-2 compliance requires minProtocolVersion and maxProtocolVersion both be set to TLSv1_2.

2. Gateway Config with Extra or Missing Cipher Suites

   apiVersion: networking.istio.io/v1alpha3
   kind: Gateway
   metadata:
     name: invalid-ciphers-gateway
   spec:
     selector:
       istio: ingressgateway
     servers:
     - port:
         number: 443
         name: https
         protocol: HTTPS
       hosts:
         - "*"
       tls:
         mode: SIMPLE
         minProtocolVersion: TLSV1_2
         maxProtocolVersion: TLSV1_2
         cipherSuites:
           # Contains more than the four strict FIPS cipher suites
           - ECDHE-RSA-AES128-GCM-SHA256
           - ECDHE-RSA-AES256-GCM-SHA384
           - TLS_AES_256_GCM_SHA384  # Not in the strict FIPS cipher set
           - ECDHE-ECDSA-AES128-GCM-SHA256
           - ECDHE-ECDSA-AES256-GCM-SHA384

   Explanation: While this configuration restricts TLS to version 1.2, it includes cipher suites (TLS_AES_256_GCM_SHA384) that are not part of the four required for strict FIPS 140-2 compliance. Only these four are allowed:

   ECDHE-ECDSA-AES128-GCM-SHA256  
   ECDHE-RSA-AES128-GCM-SHA256   
   ECDHE-ECDSA-AES256-GCM-SHA384 
   ECDHE-RSA-AES256-GCM-SHA384

Recommendation

1. Restrict TLS to Version 1.2

   Set both minProtocolVersion and maxProtocolVersion to TLSV1_2 in your Gateway TLS configuration:

   tls:
     minProtocolVersion: TLSV1_2
     maxProtocolVersion: TLSV1_2

2. Use Only FIPS-Approved Cipher Suites

   Include only these four cipher suites in the cipherSuites list:

   ECDHE-ECDSA-AES128-GCM-SHA256
   ECDHE-RSA-AES128-GCM-SHA256
   ECDHE-ECDSA-AES256-GCM-SHA384
   ECDHE-RSA-AES256-GCM-SHA384

3. Validate Gateway Configuration

   • Use Istio’s built-in checks or similar logic (like the checkTLS snippet) to confirm that TLS versions and cipher suites align with strict FIPS 140-2.
   • Attempt a TLS 1.3 handshake (-tls1_3) against the gateway to confirm it is rejected.