diff --git a/x-pack/filebeat/input/httpjson/config_auth.go b/x-pack/filebeat/input/httpjson/config_auth.go
index 71911cd6f46c..b4368f5baa2a 100644
--- a/x-pack/filebeat/input/httpjson/config_auth.go
+++ b/x-pack/filebeat/input/httpjson/config_auth.go
@@ -22,9 +22,6 @@ import (
 	"github.com/elastic/beats/v7/libbeat/common"
 )
 
-// authStyleInParams sends the "client_id" and "client_secret" in the POST body as application/x-www-form-urlencoded parameters.
-const authStyleInParams = 1
-
 type authConfig struct {
 	Basic  *basicAuthConfig `config:"basic"`
 	OAuth2 *oAuth2Config    `config:"oauth2"`
@@ -84,7 +81,7 @@ type oAuth2Config struct {
 
 	// common oauth fields
 	ClientID       string              `config:"client.id"`
-	ClientSecret   string              `config:"client.secret"`
+	ClientSecret   *string             `config:"client.secret"`
 	EndpointParams map[string][]string `config:"endpoint_params"`
 	Password       string              `config:"password"`
 	Provider       oAuth2Provider      `config:"provider"`
@@ -114,7 +111,7 @@ func (o *oAuth2Config) isEnabled() bool {
 func (o *oAuth2Config) clientCredentialsGrant(ctx context.Context, _ *http.Client) *http.Client {
 	creds := clientcredentials.Config{
 		ClientID:       o.ClientID,
-		ClientSecret:   o.ClientSecret,
+		ClientSecret:   maybeString(o.ClientSecret),
 		TokenURL:       o.getTokenURL(),
 		Scopes:         o.Scopes,
 		EndpointParams: o.getEndpointParams(),
@@ -131,10 +128,10 @@ func (o *oAuth2Config) client(ctx context.Context, client *http.Client) (*http.C
 		if o.User != "" || o.Password != "" {
 			conf := &oauth2.Config{
 				ClientID:     o.ClientID,
-				ClientSecret: o.ClientSecret,
+				ClientSecret: maybeString(o.ClientSecret),
 				Endpoint: oauth2.Endpoint{
 					TokenURL:  o.TokenURL,
-					AuthStyle: authStyleInParams,
+					AuthStyle: oauth2.AuthStyleAutoDetect,
 				},
 			}
 			token, err := conf.PasswordCredentialsToken(ctx, o.User, o.Password)
@@ -167,6 +164,14 @@ func (o *oAuth2Config) client(ctx context.Context, client *http.Client) (*http.C
 	}
 }
 
+// maybeString returns the string pointed to by p or "" if p in nil.
+func maybeString(p *string) string {
+	if p == nil {
+		return ""
+	}
+	return *p
+}
+
 // getTokenURL returns the TokenURL.
 func (o *oAuth2Config) getTokenURL() string {
 	switch o.getProvider() {
@@ -211,7 +216,7 @@ func (o *oAuth2Config) Validate() error {
 	case oAuth2ProviderGoogle:
 		return o.validateGoogleProvider()
 	case oAuth2ProviderDefault:
-		if o.TokenURL == "" || o.ClientID == "" || o.ClientSecret == "" {
+		if o.TokenURL == "" || o.ClientID == "" || o.ClientSecret == nil {
 			return errors.New("both token_url and client credentials must be provided")
 		}
 		if (o.User != "" && o.Password == "") || (o.User == "" && o.Password != "") {
@@ -228,7 +233,7 @@ func (o *oAuth2Config) Validate() error {
 var findDefaultGoogleCredentials = google.FindDefaultCredentials
 
 func (o *oAuth2Config) validateGoogleProvider() error {
-	if o.TokenURL != "" || o.ClientID != "" || o.ClientSecret != "" ||
+	if o.TokenURL != "" || o.ClientID != "" || o.ClientSecret != nil ||
 		o.AzureTenantID != "" || o.AzureResource != "" || len(o.EndpointParams) != 0 {
 		return errors.New("none of token_url and client credentials can be used, use google.credentials_file, google.jwt_file, google.credentials_json or ADC instead")
 	}
@@ -295,7 +300,7 @@ func (o *oAuth2Config) validateAzureProvider() error {
 	if o.TokenURL != "" && o.AzureTenantID != "" {
 		return errors.New("only one of token_url and tenant_id can be used")
 	}
-	if o.ClientID == "" || o.ClientSecret == "" {
+	if o.ClientID == "" || o.ClientSecret == nil {
 		return errors.New("client credentials must be provided")
 	}
 
diff --git a/x-pack/filebeat/input/httpjson/config_test.go b/x-pack/filebeat/input/httpjson/config_test.go
index 2ee8c4276c6a..116ea617e3b1 100644
--- a/x-pack/filebeat/input/httpjson/config_test.go
+++ b/x-pack/filebeat/input/httpjson/config_test.go
@@ -152,6 +152,32 @@ func TestConfigOauth2Validation(t *testing.T) {
 				"auth.oauth2": map[string]interface{}{},
 			},
 		},
+		{
+			name: "client credential secret may be empty",
+			input: map[string]interface{}{
+				"auth.oauth2": map[string]interface{}{
+					"enabled":   true,
+					"token_url": "localhost",
+					"client": map[string]interface{}{
+						"id":     "a_client_id",
+						"secret": "",
+					},
+				},
+			},
+		},
+		{
+			name:        "client credential secret may not be missing",
+			expectedErr: "both token_url and client credentials must be provided accessing 'auth.oauth2'",
+			input: map[string]interface{}{
+				"auth.oauth2": map[string]interface{}{
+					"enabled":   true,
+					"token_url": "localhost",
+					"client": map[string]interface{}{
+						"id": "a_client_id",
+					},
+				},
+			},
+		},
 		{
 			name: "if user and password is set oauth2 must use user-password authentication",
 			input: map[string]interface{}{