Google CloudOverview
Secure Sockets Layer (SSL) policies determine what port Transport Layer Security (TLS) features clients are permitted to use when connecting to load balancers. To prevent usage of insecure features, SSL policies should use (a) at least TLS 1.2 with the MODERN profile; or (b) the RESTRICTED profile, because it effectively requires clients to use TLS 1.2 regardless of the chosen minimum TLS version; or (3) a CUSTOM profile that does not support any of the following features:
TLS_RSA_WITH_AES_128_GCM_SHA256
TLS_RSA_WITH_AES_256_GCM_SHA384
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_AES_256_CBC_SHA
TLS_RSA_WITH_3DES_EDE_CBC_SHA
Rationale
Load balancers are used to efficiently distribute traffic across multiple servers. Both SSL proxy and HTTPS load balancers are external load balancers, meaning they distribute traffic from the Internet to a GCP network. GCP customers can configure load balancer SSL policies with a minimum TLS version (1.0, 1.1, or 1.2) that clients can use to establish a connection, along with a profile (Compatible, Modern, Restricted, or Custom) that specifies permissible cipher suites. To comply with users using outdated protocols, GCP load balancers can be configured to permit insecure cipher suites. In fact, the GCP default SSL policy uses a minimum TLS version of 1.0 and a Compatible profile, which allows the widest range of insecure cipher suites. As a result, it is easy for customers to configure a load balancer without even knowing that they are permitting outdated cipher suites.
Impact
Creating more secure SSL policies can prevent clients using older TLS versions from establishing a connection.
Remediation guidance
From Google Cloud Console
If the TargetSSLProxy or TargetHttpsProxy does not have an SSL policy configured, create a new SSL policy. Otherwise, modify the existing insecure policy.
- Navigate to the SSL Policies page by visiting: https://console.cloud.google.com/net-security/sslpolicies
- Click on the name of the insecure policy to go to its SSL policy details page.
- Click
EDIT. - Set
Minimum TLS versiontoTLS 1.2. - Set
ProfiletoModernorRestricted. - Alternatively, if the user selects the profile
Custom, make sure that the following features are disabled:
TLS_RSA_WITH_AES_128_GCM_SHA256
TLS_RSA_WITH_AES_256_GCM_SHA384
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_AES_256_CBC_SHA
TLS_RSA_WITH_3DES_EDE_CBC_SHA
Using Google Cloud CLI
- For each insecure SSL policy, update it to use secure cyphers:
gcloud compute ssl-policies update <name> [--profile COMPATIBLE|MODERN|RESTRICTED|CUSTOM] --min-tls-version 1.2 [--custom-features <features> ]
- If the target proxy has a GCP default SSL policy, use the following command corresponding to the proxy type to update it.
gcloud compute target-ssl-proxies update <targetSSLProxyName> --ssl-policy
gcloud compute target-https-proxies update <targetHTTPSProxyName> --sslpolicy
Default Value
The GCP default SSL policy is the least secure setting: Min TLS 1.0 and Compatible profile
References
- https://cloud.google.com/load-balancing/docs/use-ssl-policies
- https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-52r2.pdf
Service-wide remediation
Recommended when many resources are affected: fix the platform baseline first so new resources inherit the secure setting, then remediate the existing flagged resources in batches.
Google Cloud
Use organization or folder policies where available, shared project templates, logs and alerting baselines, and IaC modules so new resources inherit the secure setting.
Operational rollout
- Fix the baseline first at the account, subscription, project, cluster, or tenant scope that owns this control.
- Remediate the currently affected resources in batches, starting with internet-exposed and production assets.
- Re-scan and track approved exceptions with an owner and expiry date.
Query logic
These are the stored checks tied to this control.
No HTTPS or SSL proxy load balancers permit SSL policies with weak cipher suites
Connectors
Covered asset types
Expected check: eq []
{
loadBalancers(
where: {OR: [
{httpsProxies_SOME: {OR: [
{sslPolicy: ""},
{hasSSLPolicy: {OR: [
{profile: "COMPATIBLE"},
{AND: [{profile: "MODERN"}, {NOT: {minTlsVersion: "TLS_1_2"}}]},
{AND: [
{profile: "CUSTOM"},
{OR: [
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_AES_128_GCM_SHA256"},
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_AES_256_GCM_SHA38"},
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_AES_128_CBC_SHA"},
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_AES_256_CBC_SHA"},
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_3DES_EDE_CBC_SHA"}
]
}
]}
]}
}
]}},
{sslProxies_SOME: {OR: [
{sslPolicy: ""},
{hasSSLPolicy: {OR: [
{profile: "COMPATIBLE"},
{AND: [{profile: "MODERN"}, {NOT: {minTlsVersion: "TLS_1_2"}}]},
{AND: [
{profile: "CUSTOM"},
{OR: [
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_AES_128_GCM_SHA256"},
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_AES_256_GCM_SHA38"},
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_AES_128_CBC_SHA"},
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_AES_256_CBC_SHA"},
{enabledFeatures_INCLUDES: "TLS_RSA_WITH_3DES_EDE_CBC_SHA"}
]
}
]}
]}
}
]}},
]}){
...AssetFragment
}
}
