Fixed syslog source panic on invalid or chunked input

main.go

@@ -179,7 +179,7 @@ var (
 	syslogProtocol = syslogScan.Flag("protocol", "Protocol to listen on. udp or tcp").String()
 	syslogTLSCert  = syslogScan.Flag("cert", "Path to TLS cert.").String()
 	syslogTLSKey   = syslogScan.Flag("key", "Path to TLS key.").String()
-	syslogFormat   = syslogScan.Flag("format", "Log format. Can be rfc3164 or rfc5424").String()
+	syslogFormat   = syslogScan.Flag("format", "Log format. Can be rfc3164 or rfc5424").Required().String()
 
 	circleCiScan      = cli.Command("circleci", "Scan CircleCI")
 	circleCiScanToken = circleCiScan.Flag("token", "CircleCI token. Can also be provided with environment variable").Envar("CIRCLECI_TOKEN").Required().String()
@@ -451,7 +451,6 @@ func run(state overseer.State) {
 	// OSS Default APK handling on
 	feature.EnableAPKHandler.Store(true)
 
-
 	// OSS Default Use Git Mirror on
 	feature.UseGitMirror.Store(true)
 

pkg/sources/syslog/syslog.go

@@ -270,8 +270,11 @@ func (s *Source) monitorConnection(ctx context.Context, conn net.Conn, chunksCha
 		ctx.Logger().V(5).Info(string(input))
 		metadata, err := s.parseSyslogMetadata(input, remote.String())
 		if err != nil {
-			ctx.Logger().V(2).Info("failed to generate metadata", "error", err)
+			// set metadata as empty to avoid panics in case parsing failed
+			metadata = &source_metadatapb.MetaData{}
+			ctx.Logger().V(2).Error(err, "failed to generate metadata")
 		}
+
 		chunksChan <- &sources.Chunk{
 			SourceName:     s.syslog.sourceName,
 			SourceID:       s.syslog.sourceID,
@@ -317,8 +320,11 @@ func (s *Source) acceptUDPConnections(ctx context.Context, netListener net.Packe
 		}
 		metadata, err := s.parseSyslogMetadata(input, remote.String())
 		if err != nil {
+			// set metadata as empty to avoid panics in case parsing failed
+			metadata = &source_metadatapb.MetaData{}
 			ctx.Logger().V(2).Info("failed to parse metadata", "error", err)
 		}
+
 		chunksChan <- &sources.Chunk{
 			SourceName:     s.syslog.sourceName,
 			SourceID:       s.syslog.sourceID,

pkg/sources/syslog/syslog_test.go

@@ -0,0 +1,120 @@
+package syslog
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/protobuf/types/known/anypb"
+
+	"github.com/trufflesecurity/trufflehog/v3/pkg/context"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/pb/source_metadatapb"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/pb/sourcespb"
+)
+
+func TestSource_parseSyslogMetadata(t *testing.T) {
+	type args struct {
+		format string
+		input  []byte
+		remote string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    *source_metadatapb.MetaData
+		wantErr bool
+	}{
+		{
+			name: "success - rfc5424",
+			args: args{
+				format: "rfc5424",
+				input:  []byte("<14>1 2025-08-05T12:00:00Z my-host my-app 1234 ID47 - Test message"),
+				remote: "127.0.0.1:5140",
+			},
+			want: &source_metadatapb.MetaData{
+				Data: &source_metadatapb.MetaData_Syslog{
+					Syslog: &source_metadatapb.Syslog{
+						Hostname:  "my-host",
+						Appname:   "my-app",
+						Procid:    "1234",
+						Timestamp: "2025-08-05 12:00:00 +0000 UTC",
+						Client:    "127.0.0.1:5140",
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "success - rfc5424",
+			args: args{
+				format: "rfc5424",
+				input:  []byte("<34>1 2023-08-05T14:30:22.123Z webserver nginx 1234 access-log - 192.168.1.100 GET /index.html 200"),
+				remote: "127.0.0.1:5140",
+			},
+			want: &source_metadatapb.MetaData{
+				Data: &source_metadatapb.MetaData_Syslog{
+					Syslog: &source_metadatapb.Syslog{
+						Hostname:  "webserver",
+						Appname:   "nginx",
+						Procid:    "1234",
+						Timestamp: "2023-08-05 14:30:22.123 +0000 UTC",
+						Client:    "127.0.0.1:5140",
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "success - rfc3164",
+			args: args{
+				format: "rfc3164",
+				input:  []byte("<34>Oct 11 22:14:15 mymachine su: 'su root' failed for lonvick on /dev/pts/8"),
+				remote: "127.0.0.1:5140",
+			},
+			want: &source_metadatapb.MetaData{
+				Data: &source_metadatapb.MetaData_Syslog{
+					Syslog: &source_metadatapb.Syslog{
+						Hostname:  "mymachine",
+						Timestamp: "2025-10-11 22:14:15 +0000 UTC",
+						Client:    "127.0.0.1:5140",
+						Facility:  "4",
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "fail - wrong format",
+			args: args{
+				format: "rfc5424",
+				input:  []byte("Test message"),
+				remote: "127.0.0.1:5140",
+			},
+			want:    nil,
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := &Source{}
+
+			conn, err := anypb.New(&sourcespb.Syslog{
+				Format: tt.args.format,
+			})
+			assert.NoError(t, err)
+
+			err = s.Init(context.Background(), "test", 0, 0, false, conn, 5)
+			assert.NoError(t, err)
+
+			got, err := s.parseSyslogMetadata(tt.args.input, tt.args.remote)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Source.parseSyslogMetadata() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Source.parseSyslogMetadata() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}