Files
certctl/internal/api/handler/est_handler_test.go
T
cowork 84d0aa2d5a fix(bundle-4): EST/SCEP Attack Surface Hardening — 3 audit findings closed
Closes 3 findings (1 High + 1 Medium + 1 Low) from
/Users/shankar/Desktop/cowork/comprehensive-audit-2026-04-25/.

Bundle 4 hardens the only attack surface reachable by an anonymous network
attacker in certctl: the unauthenticated EST + SCEP enrollment endpoints.

Findings closed:

  - H-004 (High): Hand-rolled ASN.1 parser had no fuzz target.
    The audit's original framing pointed at internal/pkcs7/, but recon
    confirmed that package is an ASN.1 ENCODER (BuildCertsOnlyPKCS7,
    ASN1Wrap*, ASN1EncodeLength) — not a parser. The actual hand-rolled
    PKCS#7 PARSING reachable via anonymous network is in
    internal/api/handler/scep.go::extractCSRFromPKCS7 +
    parseSignedDataForCSR. Added native go fuzz targets:
      * internal/api/handler/scep_fuzz_test.go::FuzzExtractCSRFromPKCS7
      * internal/api/handler/scep_fuzz_test.go::FuzzParseSignedDataForCSR
      * internal/pkcs7/pkcs7_fuzz_test.go::FuzzPEMToDERChain (defense-in-depth)
      * internal/pkcs7/pkcs7_fuzz_test.go::FuzzASN1EncodeLength (defense-in-depth)
    Local 15s fuzz session: 150k execs on FuzzExtractCSRFromPKCS7,
    937k on FuzzPEMToDERChain, 925k on FuzzASN1EncodeLength — zero panics.

  - M-021 (Medium): EST TLS-Unique channel binding (RFC 7030 §3.2.3).
    Added internal/api/handler/est.go::verifyESTTransport — defense-in-depth
    TLS pre-conditions (r.TLS != nil; HandshakeComplete; TLS ≥ 1.2).
    The full §3.2.3 channel binding only applies when EST mTLS is in use;
    certctl does not currently support EST mTLS, so the §3.2.3 requirement
    is moot today. RFC 9266 (TLS 1.3 tls-exporter) and EST mTLS are
    documented as deferred follow-ups in the verifyESTTransport doc comment.

  - L-005 (Low): EST/SCEP issuer-binding fail-loud at startup.
    Pre-Bundle-4 cmd/server/main.go validated that CERTCTL_EST_ISSUER_ID and
    CERTCTL_SCEP_ISSUER_ID existed in the registry but did NOT validate the
    issuer TYPE could emit a CA cert. An operator binding EST to an ACME
    issuer (whose GetCACertPEM returns explicit error) booted successfully
    and only failed at first /est/cacerts request. Post-Bundle-4: new
    preflightEnrollmentIssuer helper calls GetCACertPEM(ctx) at startup
    with a 10s timeout. Failure logs the connector error + the candidate
    issuer types and os.Exit(1).

Tests added/modified:
  - internal/api/handler/est_transport_test.go (new) — 5 verifyESTTransport
    table cases covering plaintext-rejected, incomplete-handshake-rejected,
    TLS 1.0 rejected, TLS 1.2/1.3 accepted
  - cmd/server/preflight_test.go (new) — TestPreflightEnrollmentIssuer
    covering nil-connector, error-from-issuer, empty-PEM, valid cases
  - internal/api/handler/est_handler_test.go (modified) — 7 POST sites
    now stamp r.TLS to satisfy the new transport pre-condition
  - internal/integration/negative_test.go (modified) — setupTestServer
    wraps the test handler with a fake-TLS-state injector so the EST
    handler receives r.TLS != nil; production paths still rely on the
    real TLS listener

Threat model reference: TB-11 (EST/SCEP client ↔ Server) per
cowork/comprehensive-audit-2026-04-25/threat-model.md.
Standards: RFC 7030 §3.2.3, RFC 8894 §3, RFC 5652, RFC 9266 (deferred).
2026-04-25 21:14:41 +00:00

429 lines
12 KiB
Go

package handler
import (
"context"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/base64"
"encoding/pem"
"errors"
"math/big"
"net/http"
"net/http/httptest"
"strings"
"testing"
"time"
"github.com/shankar0123/certctl/internal/domain"
"github.com/shankar0123/certctl/internal/pkcs7"
)
// mockESTService implements ESTService for testing.
type mockESTService struct {
CACertPEM string
CACertErr error
EnrollResult *domain.ESTEnrollResult
EnrollErr error
CSRAttrs []byte
CSRAttrsErr error
}
func (m *mockESTService) GetCACerts(ctx context.Context) (string, error) {
return m.CACertPEM, m.CACertErr
}
func (m *mockESTService) SimpleEnroll(ctx context.Context, csrPEM string) (*domain.ESTEnrollResult, error) {
return m.EnrollResult, m.EnrollErr
}
func (m *mockESTService) SimpleReEnroll(ctx context.Context, csrPEM string) (*domain.ESTEnrollResult, error) {
return m.EnrollResult, m.EnrollErr
}
func (m *mockESTService) GetCSRAttrs(ctx context.Context) ([]byte, error) {
return m.CSRAttrs, m.CSRAttrsErr
}
// generateTestCSRPEM creates a valid ECDSA P-256 CSR for testing.
func generateTestCSRPEM(t *testing.T) string {
t.Helper()
key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
t.Fatalf("failed to generate key: %v", err)
}
template := &x509.CertificateRequest{
Subject: pkix.Name{CommonName: "test.example.com"},
DNSNames: []string{"test.example.com", "www.example.com"},
}
csrDER, err := x509.CreateCertificateRequest(rand.Reader, template, key)
if err != nil {
t.Fatalf("failed to create CSR: %v", err)
}
return string(pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE REQUEST", Bytes: csrDER}))
}
// generateTestCSRBase64DER creates a valid base64-encoded DER CSR for EST wire format.
func generateTestCSRBase64DER(t *testing.T) string {
t.Helper()
key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
t.Fatalf("failed to generate key: %v", err)
}
template := &x509.CertificateRequest{
Subject: pkix.Name{CommonName: "test.example.com"},
DNSNames: []string{"test.example.com"},
}
csrDER, err := x509.CreateCertificateRequest(rand.Reader, template, key)
if err != nil {
t.Fatalf("failed to create CSR: %v", err)
}
return base64.StdEncoding.EncodeToString(csrDER)
}
// generateTestCertPEM creates a real self-signed certificate PEM for testing.
func generateTestCertPEM(t *testing.T) string {
t.Helper()
key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
t.Fatalf("failed to generate key: %v", err)
}
template := &x509.Certificate{
SerialNumber: big.NewInt(1),
Subject: pkix.Name{CommonName: "Test CA"},
NotBefore: time.Now().Add(-1 * time.Hour),
NotAfter: time.Now().Add(24 * time.Hour),
KeyUsage: x509.KeyUsageCertSign | x509.KeyUsageCRLSign,
IsCA: true,
BasicConstraintsValid: true,
}
certDER, err := x509.CreateCertificate(rand.Reader, template, template, &key.PublicKey, key)
if err != nil {
t.Fatalf("failed to create certificate: %v", err)
}
return string(pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER}))
}
func TestESTCACerts_Success(t *testing.T) {
certPEM := generateTestCertPEM(t)
svc := &mockESTService{
CACertPEM: certPEM,
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodGet, "/.well-known/est/cacerts", nil)
w := httptest.NewRecorder()
h.CACerts(w, req)
if w.Code != http.StatusOK {
t.Errorf("expected 200, got %d: %s", w.Code, w.Body.String())
}
ct := w.Header().Get("Content-Type")
if !strings.Contains(ct, "application/pkcs7-mime") {
t.Errorf("expected application/pkcs7-mime content type, got %s", ct)
}
cte := w.Header().Get("Content-Transfer-Encoding")
if cte != "base64" {
t.Errorf("expected base64 content-transfer-encoding, got %s", cte)
}
}
func TestESTCACerts_MethodNotAllowed(t *testing.T) {
svc := &mockESTService{}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodPost, "/.well-known/est/cacerts", nil)
w := httptest.NewRecorder()
h.CACerts(w, req)
if w.Code != http.StatusMethodNotAllowed {
t.Errorf("expected 405, got %d", w.Code)
}
}
func TestESTCACerts_ServiceError(t *testing.T) {
svc := &mockESTService{
CACertErr: errors.New("issuer unavailable"),
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodGet, "/.well-known/est/cacerts", nil)
w := httptest.NewRecorder()
h.CACerts(w, req)
if w.Code != http.StatusInternalServerError {
t.Errorf("expected 500, got %d", w.Code)
}
}
func TestESTSimpleEnroll_Success_PEM(t *testing.T) {
csrPEM := generateTestCSRPEM(t)
certPEM := generateTestCertPEM(t)
svc := &mockESTService{
EnrollResult: &domain.ESTEnrollResult{
CertPEM: certPEM,
ChainPEM: certPEM,
},
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodPost, "/.well-known/est/simpleenroll", strings.NewReader(csrPEM))
req.TLS = &tls.ConnectionState{HandshakeComplete: true, Version: tls.VersionTLS13}
req.Header.Set("Content-Type", "application/pkcs10")
w := httptest.NewRecorder()
h.SimpleEnroll(w, req)
if w.Code != http.StatusOK {
t.Errorf("expected 200, got %d: %s", w.Code, w.Body.String())
}
ct := w.Header().Get("Content-Type")
if !strings.Contains(ct, "application/pkcs7-mime") {
t.Errorf("expected application/pkcs7-mime, got %s", ct)
}
}
func TestESTSimpleEnroll_Success_Base64DER(t *testing.T) {
csrB64 := generateTestCSRBase64DER(t)
certPEM := generateTestCertPEM(t)
svc := &mockESTService{
EnrollResult: &domain.ESTEnrollResult{
CertPEM: certPEM,
ChainPEM: "",
},
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodPost, "/.well-known/est/simpleenroll", strings.NewReader(csrB64))
req.TLS = &tls.ConnectionState{HandshakeComplete: true, Version: tls.VersionTLS13}
req.Header.Set("Content-Type", "application/pkcs10")
w := httptest.NewRecorder()
h.SimpleEnroll(w, req)
if w.Code != http.StatusOK {
t.Errorf("expected 200, got %d: %s", w.Code, w.Body.String())
}
}
func TestESTSimpleEnroll_MethodNotAllowed(t *testing.T) {
svc := &mockESTService{}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodGet, "/.well-known/est/simpleenroll", nil)
w := httptest.NewRecorder()
h.SimpleEnroll(w, req)
if w.Code != http.StatusMethodNotAllowed {
t.Errorf("expected 405, got %d", w.Code)
}
}
func TestESTSimpleEnroll_EmptyBody(t *testing.T) {
svc := &mockESTService{}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodPost, "/.well-known/est/simpleenroll", strings.NewReader(""))
req.TLS = &tls.ConnectionState{HandshakeComplete: true, Version: tls.VersionTLS13}
w := httptest.NewRecorder()
h.SimpleEnroll(w, req)
if w.Code != http.StatusBadRequest {
t.Errorf("expected 400, got %d", w.Code)
}
}
func TestESTSimpleEnroll_InvalidCSR(t *testing.T) {
svc := &mockESTService{}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodPost, "/.well-known/est/simpleenroll", strings.NewReader("not-a-valid-csr"))
req.TLS = &tls.ConnectionState{HandshakeComplete: true, Version: tls.VersionTLS13}
w := httptest.NewRecorder()
h.SimpleEnroll(w, req)
if w.Code != http.StatusBadRequest {
t.Errorf("expected 400, got %d", w.Code)
}
}
func TestESTSimpleEnroll_ServiceError(t *testing.T) {
csrPEM := generateTestCSRPEM(t)
svc := &mockESTService{
EnrollErr: errors.New("issuance failed"),
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodPost, "/.well-known/est/simpleenroll", strings.NewReader(csrPEM))
req.TLS = &tls.ConnectionState{HandshakeComplete: true, Version: tls.VersionTLS13}
w := httptest.NewRecorder()
h.SimpleEnroll(w, req)
if w.Code != http.StatusInternalServerError {
t.Errorf("expected 500, got %d", w.Code)
}
}
func TestESTSimpleReEnroll_Success(t *testing.T) {
csrPEM := generateTestCSRPEM(t)
certPEM := generateTestCertPEM(t)
svc := &mockESTService{
EnrollResult: &domain.ESTEnrollResult{
CertPEM: certPEM,
ChainPEM: certPEM,
},
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodPost, "/.well-known/est/simplereenroll", strings.NewReader(csrPEM))
req.TLS = &tls.ConnectionState{HandshakeComplete: true, Version: tls.VersionTLS13}
w := httptest.NewRecorder()
h.SimpleReEnroll(w, req)
if w.Code != http.StatusOK {
t.Errorf("expected 200, got %d: %s", w.Code, w.Body.String())
}
}
func TestESTSimpleReEnroll_MethodNotAllowed(t *testing.T) {
svc := &mockESTService{}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodGet, "/.well-known/est/simplereenroll", nil)
w := httptest.NewRecorder()
h.SimpleReEnroll(w, req)
if w.Code != http.StatusMethodNotAllowed {
t.Errorf("expected 405, got %d", w.Code)
}
}
func TestESTCSRAttrs_NoContent(t *testing.T) {
svc := &mockESTService{
CSRAttrs: nil,
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodGet, "/.well-known/est/csrattrs", nil)
w := httptest.NewRecorder()
h.CSRAttrs(w, req)
if w.Code != http.StatusNoContent {
t.Errorf("expected 204, got %d", w.Code)
}
}
func TestESTCSRAttrs_WithData(t *testing.T) {
svc := &mockESTService{
CSRAttrs: []byte{0x30, 0x00}, // empty SEQUENCE
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodGet, "/.well-known/est/csrattrs", nil)
w := httptest.NewRecorder()
h.CSRAttrs(w, req)
if w.Code != http.StatusOK {
t.Errorf("expected 200, got %d", w.Code)
}
ct := w.Header().Get("Content-Type")
if ct != "application/csrattrs" {
t.Errorf("expected application/csrattrs, got %s", ct)
}
}
func TestESTCSRAttrs_MethodNotAllowed(t *testing.T) {
svc := &mockESTService{}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodPost, "/.well-known/est/csrattrs", nil)
w := httptest.NewRecorder()
h.CSRAttrs(w, req)
if w.Code != http.StatusMethodNotAllowed {
t.Errorf("expected 405, got %d", w.Code)
}
}
func TestBuildCertsOnlyPKCS7_ViaSharedPackage(t *testing.T) {
// Test with a dummy DER certificate via shared pkcs7 package
dummyCert := []byte{0x30, 0x82, 0x01, 0x00} // minimal ASN.1 SEQUENCE
result, err := pkcs7.BuildCertsOnlyPKCS7([][]byte{dummyCert})
if err != nil {
t.Fatalf("BuildCertsOnlyPKCS7 failed: %v", err)
}
if len(result) == 0 {
t.Error("expected non-empty PKCS#7 output")
}
// Verify it starts with SEQUENCE tag
if result[0] != 0x30 {
t.Errorf("expected PKCS#7 to start with SEQUENCE tag (0x30), got 0x%02x", result[0])
}
}
func TestPemToDERChain_ViaSharedPackage(t *testing.T) {
pemData := generateTestCertPEM(t)
certs, err := pkcs7.PEMToDERChain(pemData)
if err != nil {
t.Fatalf("PEMToDERChain failed: %v", err)
}
if len(certs) != 1 {
t.Errorf("expected 1 cert, got %d", len(certs))
}
}
func TestPemToDERChain_NoCerts_ViaSharedPackage(t *testing.T) {
_, err := pkcs7.PEMToDERChain("not a PEM")
if err == nil {
t.Error("expected error for invalid PEM")
}
}
func TestESTCSRAttrs_ServiceError(t *testing.T) {
svc := &mockESTService{
CSRAttrsErr: errors.New("service error"),
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodGet, "/.well-known/est/csrattrs", nil)
w := httptest.NewRecorder()
h.CSRAttrs(w, req)
if w.Code != http.StatusInternalServerError {
t.Errorf("expected 500, got %d", w.Code)
}
}
func TestESTSimpleReEnroll_ServiceError(t *testing.T) {
csrPEM := generateTestCSRPEM(t)
svc := &mockESTService{
EnrollErr: errors.New("renewal failed"),
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodPost, "/.well-known/est/simplereenroll", strings.NewReader(csrPEM))
req.TLS = &tls.ConnectionState{HandshakeComplete: true, Version: tls.VersionTLS13}
w := httptest.NewRecorder()
h.SimpleReEnroll(w, req)
if w.Code != http.StatusInternalServerError {
t.Errorf("expected 500, got %d", w.Code)
}
}
func TestESTCACerts_UnableToGetCerts(t *testing.T) {
svc := &mockESTService{
CACertErr: errors.New("CA unavailable"),
}
h := NewESTHandler(svc)
req := httptest.NewRequest(http.MethodGet, "/.well-known/est/cacerts", nil)
w := httptest.NewRecorder()
h.CACerts(w, req)
if w.Code != http.StatusInternalServerError {
t.Errorf("expected 500, got %d", w.Code)
}
}