[Auditbeat] File Integrity ECS update (#18012)

* Add extension, mime_type and drive_letter

* run go mod vendor

* Add ECS categorization fields

* mage fmt

* Update hash and NOTICE

* Update test

* Run mage vendor

* Add changelog entry

* Extract isASCIILetter

* switch over to godoc style comment

CHANGELOG.next.asciidoc

@@ -233,6 +233,8 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Add system module package dataset ECS categorization fields. {pull}18033[18033]
 - Add system module login dataset ECS categorization fields. {pull}18034[18034]
 - Add system module user dataset ECS categorization fields. {pull}18035[18035]
+- Add file integrity module ECS categorization fields. {pull}18012[18012]
+- Add `file.mime_type`, `file.extension`, and `file.drive_letter` for file integrity module. {pull}18012[18012]
 
 *Filebeat*
 

NOTICE.txt

@@ -3261,6 +3261,37 @@ ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+--------------------------------------------------------------------
+Dependency: github.com/h2non/filetype
+Version: v1.0.12
+License type (autodetected): MIT
+./vendor/github.com/h2non/filetype/LICENSE:
+--------------------------------------------------------------------
+The MIT License
+
+Copyright (c) Tomas Aparicio
+
+Permission is hereby granted, free of charge, to any person
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without
+restriction, including without limitation the rights to use,
+copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
 --------------------------------------------------------------------
 Dependency: github.com/hashicorp/errwrap
 Version: v1.0.0

auditbeat/module/file_integrity/action.go

@@ -20,6 +20,8 @@ package file_integrity
 import (
 	"math/bits"
 	"strings"
+
+	"github.com/elastic/beats/v7/libbeat/common"
 )
 
 // Action is a description of the changes described by an event.
@@ -51,6 +53,17 @@ var actionNames = map[Action]string{
 	InitialScan:        "initial_scan",
 }
 
+var ecsActionNames = map[Action]string{
+	None:               "info",
+	AttributesModified: "change",
+	Created:            "creation",
+	Deleted:            "deletion",
+	Updated:            "change",
+	Moved:              "change",
+	ConfigChange:       "change",
+	InitialScan:        "info",
+}
+
 type actionOrderKey struct {
 	ExistsBefore, ExistsNow bool
 	Action                  Action
@@ -102,6 +115,22 @@ func (action Action) String() string {
 	return strings.Join(list, "|")
 }
 
+// ECSTypes returns the ECS categorization types associated with the
+// particular action.
+func (action Action) ECSTypes() []string {
+	if name, found := ecsActionNames[action]; found {
+		return []string{name}
+	}
+	var list []string
+	for flag, name := range ecsActionNames {
+		if action&flag != 0 {
+			action ^= flag
+			list = append(list, name)
+		}
+	}
+	return common.MakeStringSet(list...).ToSlice()
+}
+
 // MarshalText marshals the Action to a textual representation of itself.
 func (action Action) MarshalText() ([]byte, error) { return []byte(action.String()), nil }
 
@@ -174,3 +203,13 @@ func (actions ActionArray) StringArray() []string {
 	}
 	return result
 }
+
+// ECSTypes returns the array of ECS categorization types for
+// the set of actions.
+func (actions ActionArray) ECSTypes() []string {
+	var list []string
+	for _, action := range actions {
+		list = append(list, action.ECSTypes()...)
+	}
+	return common.MakeStringSet(list...).ToSlice()
+}

auditbeat/module/file_integrity/event.go

@@ -31,6 +31,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/cespare/xxhash/v2"
@@ -214,6 +215,24 @@ func NewEvent(
 	return NewEventFromFileInfo(path, info, err, action, source, maxFileSize, hashTypes)
 }
 
+func isASCIILetter(letter byte) bool {
+	// It appears that Windows only allows ascii characters for drive letters
+	// and that's what go checks for: https://golang.org/src/path/filepath/path_windows.go#L63
+	// **If** Windows/go ever return multibyte utf16 characters we'll need to change
+	// the drive letter mapping logic.
+	return (letter >= 'a' && letter <= 'z') || (letter >= 'A' && letter <= 'Z')
+}
+
+func getDriveLetter(path string) string {
+	volume := filepath.VolumeName(path)
+	if len(volume) == 2 && volume[1] == ':' {
+		if isASCIILetter(volume[0]) {
+			return strings.ToUpper(volume[:1])
+		}
+	}
+	return ""
+}
+
 func buildMetricbeatEvent(e *Event, existedBefore bool) mb.Event {
 	file := common.MapStr{
 		"path": e.Path,
@@ -237,6 +256,12 @@ func buildMetricbeatEvent(e *Event, existedBefore bool) mb.Event {
 		file["ctime"] = info.CTime
 
 		if e.Info.Type == FileType {
+			if extension := filepath.Ext(e.Path); extension != "" {
+				file["extension"] = extension
+			}
+			if mimeType := getMimeType(e.Path); mimeType != "" {
+				file["mime_type"] = mimeType
+			}
 			file["size"] = info.Size
 		}
 
@@ -245,6 +270,9 @@ func buildMetricbeatEvent(e *Event, existedBefore bool) mb.Event {
 		}
 
 		if runtime.GOOS == "windows" {
+			if drive := getDriveLetter(e.Path); drive != "" {
+				file["drive_letter"] = drive
+			}
 			if info.SID != "" {
 				file["uid"] = info.SID
 			}
@@ -276,12 +304,19 @@ func buildMetricbeatEvent(e *Event, existedBefore bool) mb.Event {
 		for hashType, digest := range e.Hashes {
 			hashes[string(hashType)] = digest
 		}
+		file["hash"] = hashes
+		// Remove this for 8.x
 		out.MetricSetFields.Put("hash", hashes)
 	}
 
+	out.MetricSetFields.Put("event.kind", "event")
+	out.MetricSetFields.Put("event.category", []string{"file"})
 	if e.Action > 0 {
-		actions := e.Action.InOrder(existedBefore, e.Info != nil).StringArray()
-		out.MetricSetFields.Put("event.action", actions)
+		actions := e.Action.InOrder(existedBefore, e.Info != nil)
+		out.MetricSetFields.Put("event.type", actions.ECSTypes())
+		out.MetricSetFields.Put("event.action", actions.StringArray())
+	} else {
+		out.MetricSetFields.Put("event.type", None.ECSTypes())
 	}
 
 	return out

auditbeat/module/file_integrity/event_test.go

@@ -37,7 +37,7 @@ var testEventTime = time.Now().UTC()
 func testEvent() *Event {
 	return &Event{
 		Timestamp: testEventTime,
-		Path:      "/home/user",
+		Path:      "/home/user/file.txt",
 		Source:    SourceScan,
 		Action:    ConfigChange,
 		Info: &Metadata{
@@ -290,8 +290,12 @@ func TestBuildEvent(t *testing.T) {
 		assert.Equal(t, testEventTime, e.Timestamp)
 
 		assertHasKey(t, fields, "event.action")
+		assertHasKey(t, fields, "event.kind")
+		assertHasKey(t, fields, "event.category")
+		assertHasKey(t, fields, "event.type")
 
 		assertHasKey(t, fields, "file.path")
+		assertHasKey(t, fields, "file.extension")
 		assertHasKey(t, fields, "file.target_path")
 		assertHasKey(t, fields, "file.inode")
 		assertHasKey(t, fields, "file.uid")
@@ -309,9 +313,51 @@ func TestBuildEvent(t *testing.T) {
 			assertHasKey(t, fields, "file.mode")
 		}
 
+		assertHasKey(t, fields, "file.hash.sha1")
+		assertHasKey(t, fields, "file.hash.sha256")
+		// Remove in 8.x
 		assertHasKey(t, fields, "hash.sha1")
 		assertHasKey(t, fields, "hash.sha256")
 	})
+	if runtime.GOOS == "windows" {
+		t.Run("drive letter", func(t *testing.T) {
+			e := testEvent()
+			e.Path = "c:\\Documents"
+			fields := buildMetricbeatEvent(e, false).MetricSetFields
+			value, err := fields.GetValue("file.drive_letter")
+			assert.NoError(t, err)
+			assert.Equal(t, "C", value)
+		})
+		t.Run("no drive letter", func(t *testing.T) {
+			e := testEvent()
+			e.Path = "\\\\remote\\Documents"
+			fields := buildMetricbeatEvent(e, false).MetricSetFields
+			_, err := fields.GetValue("file.drive_letter")
+			assert.Error(t, err)
+		})
+	}
+	t.Run("ecs categorization", func(t *testing.T) {
+		e := testEvent()
+		e.Action = ConfigChange
+		fields := buildMetricbeatEvent(e, false).MetricSetFields
+		types, err := fields.GetValue("event.type")
+		if err != nil {
+			t.Fatal(err)
+		}
+		ecsTypes, ok := types.([]string)
+		assert.True(t, ok)
+		assert.Equal(t, []string{"change"}, ecsTypes)
+
+		e.Action = Action(Created | Updated | Deleted)
+		fields = buildMetricbeatEvent(e, false).MetricSetFields
+		types, err = fields.GetValue("event.type")
+		if err != nil {
+			t.Fatal(err)
+		}
+		ecsTypes, ok = types.([]string)
+		assert.True(t, ok)
+		assert.Equal(t, []string{"change", "creation", "deletion"}, ecsTypes)
+	})
 	t.Run("no setuid/setgid", func(t *testing.T) {
 		e := testEvent()
 		e.Info.SetGID = false

auditbeat/module/file_integrity/mime.go

@@ -0,0 +1,53 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package file_integrity
+
+import (
+	"github.com/h2non/filetype"
+
+	"github.com/elastic/beats/v7/libbeat/common/file"
+)
+
+const (
+	// Size for mime detection, office file
+	// detection requires ~8kb to detect properly
+	headerSize = 8192
+)
+
+// getMimeType does a best-effort to get the file type, if no
+// filetype can be determined, it just returns an empty
+// string
+func getMimeType(path string) string {
+	f, err := file.ReadOpen(path)
+	if err != nil {
+		return ""
+	}
+	defer f.Close()
+
+	head := make([]byte, headerSize)
+	n, err := f.Read(head)
+	if err != nil {
+		return ""
+	}
+
+	kind, err := filetype.Match(head[:n])
+	if err != nil {
+		return ""
+	}
+	return kind.MIME.Value
+}

go.mod

@@ -93,6 +93,7 @@ require (
 	github.com/gorilla/mux v1.7.2 // indirect
 	github.com/gorilla/websocket v1.4.1 // indirect
 	github.com/grpc-ecosystem/grpc-gateway v1.13.0 // indirect
+	github.com/h2non/filetype v1.0.12
 	github.com/hashicorp/go-multierror v1.0.0
 	github.com/hashicorp/golang-lru v0.5.2-0.20190520140433-59383c442f7d // indirect
 	github.com/insomniacslk/dhcp v0.0.0-20180716145214-633285ba52b2

go.sum

@@ -389,6 +389,9 @@ github.com/gorilla/websocket v1.4.1/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/ad
 github.com/gregjones/httpcache v0.0.0-20170728041850-787624de3eb7/go.mod h1:FecbI9+v66THATjSRHfNgh1IVFe/9kFxbXtjV0ctIMA=
 github.com/grpc-ecosystem/grpc-gateway v1.13.0 h1:sBDQoHXrOlfPobnKw69FIKa1wg9qsLLvvQ/Y19WtFgI=
 github.com/grpc-ecosystem/grpc-gateway v1.13.0/go.mod h1:8XEsbTttt/W+VvjtQhLACqCisSPWTxCZ7sBRjU6iH9c=
+github.com/h2non/filetype v1.0.12 h1:yHCsIe0y2cvbDARtJhGBTD2ecvqMSTvlIcph9En/Zao=
+github.com/h2non/filetype v1.0.12/go.mod h1:319b3zT68BvV+WRj7cwy856M2ehB3HqNOt6sy1HndBY=
+github.com/hashicorp/errwrap v0.0.0-20141028054710-7554cd9344ce h1:prjrVgOk2Yg6w+PflHoszQNLTUh4kaByUcEWM/9uin4=
 github.com/hashicorp/errwrap v0.0.0-20141028054710-7554cd9344ce/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
 github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
 github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=