Kubernetes
EXPERIMENTAL
This feature might change without preserving backwards compatibility.
Trivy can connect to your Kubernetes cluster and scan it for security issues using the trivy k8s command. This page covers the technical capabilities of Trivy Kubernetes scanning.
Trivy can also be installed inside your cluster as a Kubernetes Operator, and continuously scan it. For more about this, please see the Trivy Operator project.
When scanning a Kubernetes cluster, Trivy differentiates between the following:
- Cluster infrastructure (e.g api-server, kubelet, addons)
- Cluster configuration (e.g Roles, ClusterRoles).
- Application workloads (e.g nginx, postgresql).
When scanning any of the above, the container image is scanned separately to the Kubernetes resource definition (the YAML manifest) that defines the resource.
Container image is scanned for:
- Vulnerabilities
- Misconfigurations
- Exposed secrets
Kubernetes resource definition is scanned for:
- Vulnerabilities (Open Source Libraries, Control Plane and Node Components)
- Misconfigurations
- Exposed secrets
Kubernetes target configurations
Trivy follows the behavior of the kubectl tool as much as possible.
Scope
The command expects an argument that selects the scope of the scan (similarly to how kubectl expects an argument after kubectl get). This argument can be:
1. A Kubernetes Kind. e.g pod, deployment, etc.
2. A Kubernetes Resource. e.g pods/mypod, etc.
3. all. Scan common workload kinds, as listed here
4. cluster scan the entire cluster including all namespaced resources and cluster level resources.
Examples:
trivy k8s all
trivy k8s pods
trivy k8s deploy myapp
trivy k8s pod/mypod
trivy k8s pods,deploy
trivy k8s cluster
Note that the scope argument must appear last in the command line, after any other flag.
Cluster
By default Trivy will look for a kubeconfig configuration file in the default location, and use the default cluster that is specified.
You can also specify a kubeconfig using the --kubeconfig flag:
trivy k8s --kubeconfig ~/.kube/config2
Namespace
By default Trivy will scan all namespaces (following kubectl behavior). To specify a namespace use the --namespace flag:
trivy k8s --kubeconfig ~/.kube/config2 --namespace default
Node
You can exclude specific nodes from the scan using the --exclude-nodes flag, which takes a label in the format label-name:label-value and excludes all matching nodes:
trivy k8s cluster --report summary --exclude-nodes kubernetes.io/arch:arm6
Control Plane and Node Components Vulnerability Scanning
Trivy is capable of discovering Kubernetes control plane (apiserver, controller-manager and etc) and node components(kubelet, kube-proxy and etc), matching them against the official Kubernetes vulnerability database feed, and reporting any vulnerabilities it finds
trivy k8s cluster --scanners vuln --report all
NodeComponents/kind-control-plane (kubernetes)
Total: 3 (UNKNOWN: 0, LOW: 1, MEDIUM: 0, HIGH: 2, CRITICAL: 0)
┌────────────────┬────────────────┬──────────┬────────┬───────────────────┬──────────────────────────────────┬───────────────────────────────────────────────────┐
│ Library │ Vulnerability │ Severity │ Status │ Installed Version │ Fixed Version │ Title │
├────────────────┼────────────────┼──────────┼────────┼───────────────────┼──────────────────────────────────┼───────────────────────────────────────────────────┤
│ k8s.io/kubelet │ CVE-2023-2431 │ LOW │ fixed │ 1.21.1 │ 1.24.14, 1.25.10, 1.26.5, 1.27.2 │ Bypass of seccomp profile enforcement │
│ │ │ │ │ │ │ https://avd.aquasec.com/nvd/cve-2023-2431 │
│ ├────────────────┼──────────┤ │ ├──────────────────────────────────┼───────────────────────────────────────────────────┤
│ │ CVE-2021-25741 │ HIGH │ │ │ 1.19.16, 1.20.11, 1.21.5, 1.22.1 │ Symlink exchange can allow host filesystem access │
│ │ │ │ │ │ │ https://avd.aquasec.com/nvd/cve-2021-25741 │
│ ├────────────────┤ │ │ ├──────────────────────────────────┼───────────────────────────────────────────────────┤
│ │ CVE-2021-25749 │ │ │ │ 1.22.14, 1.23.11, 1.24.5 │ runAsNonRoot logic bypass for Windows containers │
│ │ │ │ │ │ │ https://avd.aquasec.com/nvd/cve-2021-25749 │
└────────────────┴────────────────┴──────────┴────────┴───────────────────┴──────────────────────────────────┴───────────────────────────────────────────────────┘
Components types
You can control what kinds of components are discovered using the --components flag:
- --components infra will discover only cluster infrastructure components.
- --components workloads will discover only application workloads.
- If the flag is omitted: infra, workloads, and RBAC are discovered.
Reporting and filtering
Since scanning an entire cluster for any security issue can be overwhelming, By default Trivy summarizes the results in a simple "summary" view.
By scoping the scan on a specific resource, you can see the detailed report.
You can always choose the report granularity using the --report summary/--report all flag.
Scan a full cluster and generate a simple summary report:
$ trivy k8s --report=summary cluster
Filter by severity:
trivy k8s --severity=CRITICAL --report=all cluster
Filter by scanners (Vulnerabilities, Secrets or Misconfigurations):
trivy k8s --scanners=secret --report=summary cluster
# or
trivy k8s --scanners=misconfig --report=summary cluster
The supported output formats are table, which is the default, and json.
trivy k8s --format json -o results.json cluster
Result
{
"ClusterName": "minikube",
"Vulnerabilities": [
{
"Namespace": "default",
"Kind": "Deployment",
"Name": "app",
"Results": [
{
"Target": "ubuntu:latest (ubuntu 22.04)",
"Class": "os-pkgs",
"Type": "ubuntu",
"Vulnerabilities": [
{
"VulnerabilityID": "CVE-2016-2781",
"PkgName": "coreutils",
"InstalledVersion": "8.32-4.1ubuntu1",
"Layer": {
"Digest": "sha256:125a6e411906fe6b0aaa50fc9d600bf6ff9bb11a8651727ce1ed482dc271c24c",
"DiffID": "sha256:e59fc94956120a6c7629f085027578e6357b48061d45714107e79f04a81a6f0c"
},
"SeveritySource": "ubuntu",
"PrimaryURL": "https://avd.aquasec.com/nvd/cve-2016-2781",
"DataSource": {
"ID": "ubuntu",
"Name": "Ubuntu CVE Tracker",
"URL": "https://git.launchpad.net/ubuntu-cve-tracker"
},
"Title": "coreutils: Non-privileged session can escape to the parent session in chroot",
"Description": "chroot in GNU coreutils, when used with --userspec, allows local users to escape to the parent session via a crafted TIOCSTI ioctl call, which pushes characters to the terminal's input buffer.",
"Severity": "LOW",
"CweIDs": [
"CWE-20"
],
"VendorSeverity": {
"cbl-mariner": 2,
"nvd": 2,
"redhat": 2,
"ubuntu": 1
},
"CVSS": {
"nvd": {
"V2Vector": "AV:L/AC:L/Au:N/C:N/I:P/A:N",
"V3Vector": "CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N",
"V2Score": 2.1,
"V3Score": 6.5
},
"redhat": {
"V2Vector": "AV:L/AC:H/Au:N/C:C/I:C/A:C",
"V3Vector": "CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
"V2Score": 6.2,
"V3Score": 8.6
}
},
"References": [
"http://seclists.org/oss-sec/2016/q1/452",
"http://www.openwall.com/lists/oss-security/2016/02/28/2",
"http://www.openwall.com/lists/oss-security/2016/02/28/3",
"https://access.redhat.com/security/cve/CVE-2016-2781",
"https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2781",
"https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772@%3Cdev.mina.apache.org%3E",
"https://lore.kernel.org/patchwork/patch/793178/",
"https://nvd.nist.gov/vuln/detail/CVE-2016-2781"
],
"PublishedDate": "2017-02-07T15:59:00Z",
"LastModifiedDate": "2021-02-25T17:15:00Z"
}
]
}
]
}
],
"Misconfigurations": [
{
"Namespace": "default",
"Kind": "Deployment",
"Name": "app",
"Results": [
{
"Target": "Deployment/app",
"Class": "config",
"Type": "kubernetes",
"MisconfSummary": {
"Successes": 20,
"Failures": 19,
"Exceptions": 0
},
"Misconfigurations": [
{
"Type": "Kubernetes Security Check",
"ID": "KSV001",
"Title": "Process can elevate its own privileges",
"Description": "A program inside the container can elevate its own privileges and run as root, which might give the program control over the container and node.",
"Message": "Container 'app' of Deployment 'app' should set 'securityContext.allowPrivilegeEscalation' to false",
"Namespace": "builtin.kubernetes.KSV001",
"Query": "data.builtin.kubernetes.KSV001.deny",
"Resolution": "Set 'set containers[].securityContext.allowPrivilegeEscalation' to 'false'.",
"Severity": "MEDIUM",
"PrimaryURL": "https://avd.aquasec.com/misconfig/ksv001",
"References": [
"https://kubernetes.io/docs/concepts/security/pod-security-standards/#restricted",
"https://avd.aquasec.com/misconfig/ksv001"
],
"Status": "FAIL",
"Layer": {},
"IacMetadata": {
"Provider": "Kubernetes",
"Service": "general",
"StartLine": 121,
"EndLine": 133
}
},
{
"Type": "Kubernetes Security Check",
"ID": "KSV003",
"Title": "Default capabilities not dropped",
"Description": "The container should drop all default capabilities and add only those that are needed for its execution.",
"Message": "Container 'app' of Deployment 'app' should add 'ALL' to 'securityContext.capabilities.drop'",
"Namespace": "builtin.kubernetes.KSV003",
"Query": "data.builtin.kubernetes.KSV003.deny",
"Resolution": "Add 'ALL' to containers[].securityContext.capabilities.drop.",
"Severity": "LOW",
"PrimaryURL": "https://avd.aquasec.com/misconfig/ksv003",
"References": [
"https://kubesec.io/basics/containers-securitycontext-capabilities-drop-index-all/",
"https://avd.aquasec.com/misconfig/ksv003"
],
"Status": "FAIL",
"Layer": {},
"IacMetadata": {
"Provider": "Kubernetes",
"Service": "general",
"StartLine": 121,
"EndLine": 133
}
}
]
}
]
},
{
"Namespace": "default",
"Kind": "ConfigMap",
"Name": "kube-root-ca.crt"
}
]
}
Compliance
This section describes Kubernetes specific compliance reports. For an overview of Trivy's Compliance feature, including working with custom compliance, check out the Compliance documentation.
The following reports are available out of the box:
| Compliance | Name for command | More info |
|---|---|---|
| NSA, CISA Kubernetes Hardening Guidance v1.2 | k8s-nsa |
Link |
| CIS Benchmark for Kubernetes v1.23 | k8s-cis |
Link |
| Pod Security Standards, Baseline | k8s-pss-baseline |
Link |
| Pod Security Standards, Restricted | k8s-pss-restricted |
Link |
Examples:
Scan the cluster for Kubernetes Pod Security Standards Baseline compliance:
$ trivy k8s cluster --compliance=k8s-pss-baseline --report summary
Get the detailed report for checks:
$ trivy k8s cluster --compliance=k8s-cis --report all
Get summary report in JSON format:
$ trivy k8s cluster --compliance=k8s-cis --report summary --format json
Get detailed report in JSON format:
$ trivy k8s cluster --compliance=k8s-cis --report all --format json
KBOM
KBOM, Kubernetes Bill of Materials, is a manifest of all the important components that make up your Kubernetes cluster – Control plane components, Node Components, and Addons, including their versions and images. Which “api-server” version are you currently running? Which flavor of "kubelet" is running on each node? What kind of etcd or storage are you currently using? And most importantly – are there any vulnerabilities known to affect these components? These are all questions that KBOM can help you answer.
For more background on KBOM, see here.
Trivy can generate KBOM in CycloneDX format:
$ trivy k8s cluster --format cyclonedx --output mykbom.cdx.json
Trivy can also scan that generated KBOM (or any SBOM) for vulnerabilities:
$ trivy sbom mykbom.cdx.json
Result
2023-09-28T22:52:25.707+0300 INFO Vulnerability scanning is enabled
2023-09-28T22:52:25.707+0300 INFO Detected SBOM format: cyclonedx-json
2023-09-28T22:52:25.717+0300 WARN No OS package is detected. Make sure you haven't deleted any files that contain information about the installed packages.
2023-09-28T22:52:25.717+0300 WARN e.g. files under "/lib/apk/db/", "/var/lib/dpkg/" and "/var/lib/rpm"
2023-09-28T22:52:25.717+0300 INFO Detected OS: debian gnu/linux
2023-09-28T22:52:25.717+0300 WARN unsupported os : debian gnu/linux
2023-09-28T22:52:25.717+0300 INFO Number of language-specific files: 3
2023-09-28T22:52:25.717+0300 INFO Detecting kubernetes vulnerabilities...
2023-09-28T22:52:25.718+0300 INFO Detecting gobinary vulnerabilities...
Kubernetes (kubernetes)
Total: 2 (UNKNOWN: 0, LOW: 1, MEDIUM: 0, HIGH: 1, CRITICAL: 0)
┌────────────────┬────────────────┬──────────┬────────┬───────────────────┬─────────────────────────────────┬──────────────────────────────────────────────────┐
│ Library │ Vulnerability │ Severity │ Status │ Installed Version │ Fixed Version │ Title │
├────────────────┼────────────────┼──────────┼────────┼───────────────────┼─────────────────────────────────┼──────────────────────────────────────────────────┤
│ k8s.io/kubelet │ CVE-2021-25749 │ HIGH │ fixed │ 1.24.0 │ 1.22.14, 1.23.11, 1.24.5 │ runAsNonRoot logic bypass for Windows containers │
│ │ │ │ │ │ │ https://avd.aquasec.com/nvd/cve-2021-25749 │
│ ├────────────────┼──────────┤ │ ├─────────────────────────────────┼──────────────────────────────────────────────────┤
│ │ CVE-2023-2431 │ LOW │ │ │ 1.24.14, 1.25.9, 1.26.4, 1.27.1 │ Bypass of seccomp profile enforcement │
│ │ │ │ │ │ │ https://avd.aquasec.com/nvd/cve-2023-2431 │
└────────────────┴────────────────┴──────────┴────────┴───────────────────┴─────────────────────────────────┴──────────────────────────────────────────────────┘
Find more in the documentation for SBOM scanning.
Currently KBOM vulnerability matching works for plain Kubernetes distributions and does not work well for vendor variants, including some cloud managed distributions.