feat: store latest challenge/attestation data (#2179)

## What kind of change does this PR introduce?

Feature - Store WebAuthn challenge data for customer verification
purposes

## What is the current behavior?

Currently, WebAuthn challenge data (attestation/assertion responses) is
not persisted after verification, making it impossible for customers to
review or audit the WebAuthn authentication details.

## What is the new behavior?

- Added `last_webauthn_challenge_data` JSONB column to `mfa_factors`
table to store the latest challenge verification data
- The system now stores the challenge, type (create/request), and parsed
credential response after successful WebAuthn verification, THEN deletes
the challenge like before.

## Additional context

The structure for the JSONb would be like so, based on whether it's a
`create` or `request` webauthn operation

```typescript
type LastWebAuthnChallengeData = {
    challenge: ChallengeData,
} & {
  type: "create"
  credential_response: ParsedCredentialCreationData
} | {
  type: "request"
  credential_response: ParsedCredentialAssertionData
}
```


---------

Co-authored-by: Stojan Dimitrovski <sdimitrovski@gmail.com>

Author: Bewinxed

internal/api/mfa.go

@@ -906,32 +906,34 @@ func (a *API) verifyWebAuthnFactor(w http.ResponseWriter, r *http.Request, param
 		return err
 	}
 	webAuthnSession := *challenge.WebAuthnSessionData.SessionData
-	// Once the challenge is validated, we consume the challenge
-	if err := db.Destroy(challenge); err != nil {
-		return apierrors.NewInternalServerError("Database error deleting challenge").WithInternalError(err)
-	}
 
+	var parsedResponse interface{}
 	switch params.WebAuthn.Type {
 	case "create":
-		parsedResponse, err := wbnprotocol.ParseCredentialCreationResponseBody(bytes.NewReader(params.WebAuthn.CredentialResponse))
+		parsedResponse, err = wbnprotocol.ParseCredentialCreationResponseBody(bytes.NewReader(params.WebAuthn.CredentialResponse))
 		if err != nil {
 			return apierrors.NewBadRequestError(apierrors.ErrorCodeValidationFailed, "Invalid credential_response")
 		}
-		credential, err = webAuthn.CreateCredential(user, webAuthnSession, parsedResponse)
+		credential, err = webAuthn.CreateCredential(user, webAuthnSession, parsedResponse.(*wbnprotocol.ParsedCredentialCreationData))
 		if err != nil {
 			return err
 		}
 
 	case "request":
-		parsedResponse, err := wbnprotocol.ParseCredentialRequestResponseBody(bytes.NewReader(params.WebAuthn.CredentialResponse))
+		parsedResponse, err = wbnprotocol.ParseCredentialRequestResponseBody(bytes.NewReader(params.WebAuthn.CredentialResponse))
 		if err != nil {
 			return apierrors.NewBadRequestError(apierrors.ErrorCodeValidationFailed, "Invalid credential_response")
 		}
-		credential, err = webAuthn.ValidateLogin(user, webAuthnSession, parsedResponse)
+		credential, err = webAuthn.ValidateLogin(user, webAuthnSession, parsedResponse.(*wbnprotocol.ParsedCredentialAssertionData))
 		if err != nil {
 			return apierrors.NewInternalServerError("Failed to validate WebAuthn MFA response").WithInternalError(err)
 		}
 	}
+
+	// Once the challenge is validated, we consume the challenge
+	if err := db.Destroy(challenge); err != nil {
+		return apierrors.NewInternalServerError("Database error deleting challenge").WithInternalError(err)
+	}
 	var token *AccessTokenResponse
 	err = db.Transaction(func(tx *storage.Connection) error {
 		var terr error
@@ -951,6 +953,10 @@ func (a *API) verifyWebAuthnFactor(w http.ResponseWriter, r *http.Request, param
 				return terr
 			}
 		}
+
+		if terr = factor.UpdateLastWebAuthnChallenge(tx, challenge, params.WebAuthn.Type, parsedResponse); terr != nil {
+			return terr
+		}
 		user, terr = models.FindUserByID(tx, user.ID)
 		if terr != nil {
 			return terr

internal/models/factor.go

@@ -139,19 +139,20 @@ func ParseAuthenticationMethod(authMethod string) (AuthenticationMethod, error)
 type Factor struct {
 	ID uuid.UUID `json:"id" db:"id"`
 	// TODO: Consider removing this nested user field. We don't use it.
-	User               User                `json:"-" belongs_to:"user"`
-	UserID             uuid.UUID           `json:"-" db:"user_id"`
-	CreatedAt          time.Time           `json:"created_at" db:"created_at"`
-	UpdatedAt          time.Time           `json:"updated_at" db:"updated_at"`
-	Status             string              `json:"status" db:"status"`
-	FriendlyName       string              `json:"friendly_name,omitempty" db:"friendly_name"`
-	Secret             string              `json:"-" db:"secret"`
-	FactorType         string              `json:"factor_type" db:"factor_type"`
-	Challenge          []Challenge         `json:"-" has_many:"challenges"`
-	Phone              storage.NullString  `json:"phone" db:"phone"`
-	LastChallengedAt   *time.Time          `json:"last_challenged_at" db:"last_challenged_at"`
-	WebAuthnCredential *WebAuthnCredential `json:"-" db:"web_authn_credential"`
-	WebAuthnAAGUID     *uuid.UUID          `json:"web_authn_aaguid,omitempty" db:"web_authn_aaguid"`
+	User                      User                       `json:"-" belongs_to:"user"`
+	UserID                    uuid.UUID                  `json:"-" db:"user_id"`
+	CreatedAt                 time.Time                  `json:"created_at" db:"created_at"`
+	UpdatedAt                 time.Time                  `json:"updated_at" db:"updated_at"`
+	Status                    string                     `json:"status" db:"status"`
+	FriendlyName              string                     `json:"friendly_name,omitempty" db:"friendly_name"`
+	Secret                    string                     `json:"-" db:"secret"`
+	FactorType                string                     `json:"factor_type" db:"factor_type"`
+	Challenge                 []Challenge                `json:"-" has_many:"challenges"`
+	Phone                     storage.NullString         `json:"phone" db:"phone"`
+	LastChallengedAt          *time.Time                 `json:"last_challenged_at" db:"last_challenged_at"`
+	WebAuthnCredential        *WebAuthnCredential        `json:"-" db:"web_authn_credential"`
+	WebAuthnAAGUID            *uuid.UUID                 `json:"web_authn_aaguid,omitempty" db:"web_authn_aaguid"`
+	LastWebAuthnChallengeData *LastWebAuthnChallengeData `json:"last_webauthn_challenge_data,omitempty" db:"last_webauthn_challenge_data"`
 }
 
 type WebAuthnCredential struct {
@@ -165,6 +166,40 @@ func (wc *WebAuthnCredential) Value() (driver.Value, error) {
 	return json.Marshal(wc)
 }
 
+type LastWebAuthnChallengeData struct {
+	Challenge          Challenge       `json:"challenge"`
+	Type               string          `json:"type"`
+	CredentialResponse json.RawMessage `json:"credential_response"`
+}
+
+func (lwcd *LastWebAuthnChallengeData) Value() (driver.Value, error) {
+	if lwcd == nil {
+		return nil, nil
+	}
+	return json.Marshal(lwcd)
+}
+
+func (lwcd *LastWebAuthnChallengeData) Scan(value interface{}) error {
+	if value == nil {
+		*lwcd = LastWebAuthnChallengeData{}
+		return nil
+	}
+	var data []byte
+	switch v := value.(type) {
+	case []byte:
+		data = v
+	case string:
+		data = []byte(v)
+	default:
+		return fmt.Errorf("unsupported type for last_webauthn_challenge_data: %T", value)
+	}
+	if len(data) == 0 {
+		*lwcd = LastWebAuthnChallengeData{}
+		return nil
+	}
+	return json.Unmarshal(data, lwcd)
+}
+
 func (wc *WebAuthnCredential) Scan(value interface{}) error {
 	if value == nil {
 		wc.Credential = webauthn.Credential{}
@@ -265,6 +300,21 @@ func (f *Factor) SaveWebAuthnCredential(tx *storage.Connection, credential *weba
 	return tx.UpdateOnly(f, "web_authn_credential", "web_authn_aaguid", "updated_at")
 }
 
+func (f *Factor) UpdateLastWebAuthnChallenge(tx *storage.Connection, challenge *Challenge, challengeType string, credentialResponse interface{}) error {
+	responseData, err := json.Marshal(credentialResponse)
+	if err != nil {
+		return fmt.Errorf("failed to marshal credential response: %w", err)
+	}
+
+	f.LastWebAuthnChallengeData = &LastWebAuthnChallengeData{
+		Challenge:          *challenge,
+		Type:               challengeType,
+		CredentialResponse: json.RawMessage(responseData),
+	}
+
+	return tx.UpdateOnly(f, "last_webauthn_challenge_data", "updated_at")
+}
+
 func FindFactorByFactorID(conn *storage.Connection, factorID uuid.UUID) (*Factor, error) {
 	var factor Factor
 	err := conn.Find(&factor, factorID)

migrations/20250925093508_add_last_webauthn_challenge_data.up.sql

@@ -0,0 +1,4 @@
+ALTER TABLE {{ index .Options "Namespace" }}.mfa_factors 
+ADD COLUMN IF NOT EXISTS last_webauthn_challenge_data JSONB;
+
+COMMENT ON COLUMN {{ index .Options "Namespace" }}.mfa_factors.last_webauthn_challenge_data IS 'Stores the latest WebAuthn challenge data including attestation/assertion for customer verification';