feat(kubeconfig): create detector

pkg/detectors/kubeconfig/kubeconfig.go

@@ -0,0 +1,221 @@
+package kubeconfig
+
+import (
+	"context"
+	"crypto/tls"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/trufflesecurity/trufflehog/v3/pkg/common"
+	logContext "github.com/trufflesecurity/trufflehog/v3/pkg/context"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/detectors"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/pb/detectorspb"
+)
+
+type Scanner struct {
+	client *http.Client
+}
+
+var (
+	// Ensure the Scanner satisfies the interface at compile time.
+	_             detectors.Detector = (*Scanner)(nil)
+	defaultClient                    = common.SaneHttpClient()
+)
+
+// Keywords are used for efficiently pre-filtering chunks.
+func (s Scanner) Keywords() []string {
+	return []string{"current-context"}
+}
+
+// FromData will find and optionally verify KubeConfig secrets in a given set of bytes.
+func (s Scanner) FromData(ctx context.Context, verify bool, data []byte) (results []detectors.Result, err error) {
+	logCtx := logContext.AddLogger(ctx)
+	logger := logCtx.Logger().WithName("kubeconfig")
+	dataStr := string(data)
+
+	// A crude method to differentiate JSON and YAML configs.
+	var (
+		clusters []cluster
+		errs     []error
+	)
+	if jsonpat.MatchString(dataStr) {
+		clusters, errs = parseJson(dataStr)
+	} else {
+		clusters, errs = parseYaml(dataStr)
+	}
+
+	if len(errs) > 0 {
+		for _, pErr := range errs {
+			// Fatal errors
+			if errors.Is(pErr, noClustersObjectError) ||
+				errors.Is(pErr, noClusterEntriesError) ||
+				errors.Is(pErr, noContextsObjectError) ||
+				errors.Is(pErr, noContextsError) ||
+				errors.Is(pErr, noUsersObjectError) ||
+				errors.Is(pErr, noUsersError) {
+				return
+			}
+
+			logger.Error(pErr, "Failed to parse config")
+		}
+	}
+	if len(clusters) == 0 {
+		return
+	}
+
+	for _, cluster := range clusters {
+		s1 := detectors.Result{
+			DetectorType: s.Type(),
+			Raw:          []byte(cluster.Auth.GetValue()),
+			RawV2:        []byte(fmt.Sprintf(`{"server":"%s","user":"%s","auth":"%s"}`, cluster.Server, cluster.GetUser(), cluster.Auth.GetValue())),
+			ExtraData: map[string]string{
+				"Server": cluster.Server,
+				"User":   cluster.User,
+				"Type":   cluster.Auth.Type.String(),
+			},
+		}
+
+		if verify {
+			client := s.client
+			if client == nil {
+				client = defaultClient
+			}
+			patchTransport(client)
+
+			verified, extraData, verificationErr := verifyCluster(logCtx, client, cluster)
+			s1.Verified = verified
+			for k, v := range extraData {
+				s1.ExtraData[k] = v
+			}
+			s1.SetVerificationError(verificationErr)
+		}
+
+		results = append(results, s1)
+	}
+
+	return
+}
+
+func verifyCluster(ctx logContext.Context, client *http.Client, cluster cluster) (bool, map[string]string, error) {
+	logger := ctx.Logger().WithName("kubeconfig")
+
+	namespacesUrl, err := url.JoinPath(cluster.Server, "/api/v1/namespaces")
+	if err != nil {
+		return false, nil, err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, namespacesUrl+"?limit=10", nil)
+	if err != nil {
+		return false, nil, nil
+	}
+
+	// https://github.com/kubernetes/kubernetes/blob/e0e6c9633d5f9a388cbf9c7757c789afaec11c34/cmd/kubeadm/app/phases/kubeconfig/kubeconfig.go#L171
+	// https://github.com/kubernetes/kubernetes/blob/e0e6c9633d5f9a388cbf9c7757c789afaec11c34/staging/src/k8s.io/client-go/plugin/pkg/client/auth/exec/exec.go#L291
+	switch cluster.Auth.Type {
+	case clientKeyAuth:
+		// Requires mutual TLS auth.
+		// Need to investigate this.
+	case passwordAuth:
+		req.SetBasicAuth(cluster.User, cluster.Auth.Password)
+	case tokenAuth:
+		req.Header.Set("Authorization", "Bearer "+cluster.Auth.Token)
+	default:
+		// This should never happen.
+		logger.Info("Skipping authentication for unknown auth type", "type", cluster.Auth.Type.String())
+	}
+	req.Header.Set("Accept", "application/json")
+	res, err := client.Do(req)
+	if err != nil {
+		return false, nil, err
+	}
+	defer func() {
+		_, _ = io.Copy(io.Discard, res.Body)
+		_ = res.Body.Close()
+	}()
+
+	body, err := io.ReadAll(res.Body)
+	if err != nil {
+		return false, nil, err
+	}
+
+	switch res.StatusCode {
+	case http.StatusOK:
+		var nsRes namespaceListResponse
+		if err := json.Unmarshal(body, &nsRes); err != nil {
+			return false, nil, err
+		}
+
+		var extraData map[string]string
+		if len(nsRes.Items) > 0 {
+			var sb strings.Builder
+			for i, ns := range nsRes.Items {
+				if i > 0 {
+					sb.WriteString(",")
+				}
+				sb.WriteString(ns.Metadata.Name)
+			}
+
+			if nsRes.Metadata.Continue != "" {
+				sb.WriteString(" (+ more)")
+			}
+
+			extraData = map[string]string{
+				"Namespaces": sb.String(),
+			}
+		}
+		return true, extraData, nil
+	case http.StatusUnauthorized:
+		// The secret is determinately not verified (nothing to do)
+		return false, nil, nil
+	case http.StatusForbidden:
+		// The auth was valid but the user lacks permission.
+		return true, nil, nil
+	default:
+		logger.Info("Received unexpected HTTP response", "user", cluster.User, "status_code", res.StatusCode, "body", string(body))
+		return false, nil, fmt.Errorf("unexpected HTTP response status %d", res.StatusCode)
+	}
+}
+
+// patchTransport disables TLS certificate validation.
+// This is necessary because many k8s clusters use self-signed certificates.
+func patchTransport(c *http.Client) {
+	transport, ok := c.Transport.(*http.Transport)
+	if !ok || transport == nil {
+		transport = &http.Transport{}
+	}
+
+	// Allow self-signed certificates.
+	transport.TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
+	c.Transport = transport
+}
+
+// https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.26/#namespacelist-v1-core
+type namespaceListResponse struct {
+	Items    []item `json:"items"`
+	Metadata listMetadata
+}
+
+type listMetadata struct {
+	Continue string `json:"continue"`
+}
+
+type item struct {
+	Metadata itemMetadata `json:"metadata"`
+}
+
+type itemMetadata struct {
+	Name string `json:"name"`
+}
+
+func (s Scanner) Type() detectorspb.DetectorType {
+	return detectorspb.DetectorType_KubeConfig
+}
+
+func (s Scanner) Description() string {
+	return "KubeConfig credentials can allow unauthorized access to a Kubernetes cluster."
+}