Detection rules › Kusto

Detect Malicious Usage of Recovery Tools to Delete Backup Files

Status
available
Severity
high
Time window
1h
Source
github.com/Azure/Azure-Sentinel

This analytic rule detects usage of recovery tools vssadmin, wbadmin, wmic and bcedit to delete backup files or change recovery configuration. Adversaries may use these tools to delete shadow copies and backup files to prevent recovery of files. https://attack.mitre.org/techniques/T1490/

MITRE ATT&CK coverage

TacticTechniques
Impact

Telemetry coverage

Rule body

id: 259de2c1-c546-4c6d-a17c-df639722f4d7
name: Detect Malicious Usage of Recovery Tools to Delete Backup Files
description: |
  This analytic rule detects usage of recovery tools vssadmin, wbadmin, wmic and bcedit to delete backup files or change recovery configuration. Adversaries may use these tools to delete shadow copies and backup files to prevent recovery of files.
  https://attack.mitre.org/techniques/T1490/
severity: High
status: Available 
tags:
  - Schema: _ASim_ProcessEvent
    SchemaVersion: 0.1.4
requiredDataConnectors:
  - connectorId: CrowdStrikeFalconEndpointProtection
    dataTypes: 
      - CommonSecurityLog
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - SecurityAlert
  - connectorId: SentinelOne
    dataTypes:
      - SentinelOne_CL
  - connectorId: VMwareCarbonBlack
    dataTypes:
      - CarbonBlackEvents_CL
  - connectorId: CiscoSecureEndpoint
    dataTypes:
      - CiscoSecureEndpoint_CL
  - connectorId: TrendMicroApexOne
    dataTypes:
      - TMApexOneEvent
  - connectorId: TrendMicroApexOneAma
    dataTypes:
      - TMApexOneEvent
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Impact
relevantTechniques:
  - T1490
query: |
  _ASim_ProcessEvent
  | where TargetProcessFilename has_any ('vssadmin.exe', 'wbadmin.exe', 'wmic.exe')
  | where CommandLine has_all ('delete', 'shadow')
  | union isfuzzy=True 
      (_ASim_ProcessEvent
      | where TargetProcessFilename =~ 'bcedit.exe'
      | where CommandLine has_all ('/set', 'recoveryenabled no')
      )
  | project
      TimeGenerated,
      DvcHostname,
      DvcIpAddr,
      DvcDomain,
      TargetUsername,
      TargetUsernameType,
      TargetProcessName,
      TargetProcessId,
      CommandLine
  | extend Username = iff(tostring(TargetUsernameType) == 'Windows', tostring(split(TargetUsername, '\\')[1]), TargetUsername)
  | extend NTDomain = iff(tostring(TargetUsernameType) == 'Windows', tostring(split(TargetUsername, '\\')[0]), TargetUsername)
  | extend Username = iff(tostring(TargetUsernameType) == 'UPN', tostring(split(TargetUsername, '@')[0]), Username)
  | extend UPNSuffix = iff(tostring(TargetUsernameType) == 'UPN', tostring(split(TargetUsername, '@')[1]), '')
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: DvcHostname
      - identifier: DnsDomain
        columnName: DvcDomain
      - identifier: NTDomain
        columnName: NTDomain
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: DvcIpAddr
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: Username
      - identifier: UPNSuffix
        columnName: UPNSuffix
      - identifier: NTDomain
        columnName: NTDomain
  - entityType: Process
    fieldMappings:
      - identifier: ProcessId
        columnName: TargetProcessId
      - identifier: CommandLine
        columnName: CommandLine
eventGroupingSettings:
  aggregationKind: AlertPerResult
alertDetailsOverride:
  alertDisplayNameFormat: "Tool {{TargetProcessName}} used to delete backup files on {{DvcHostname}} by {{TargetUsername}}"
  alertDescriptionFormat: "A system tool {{TargetProcessName}} ProcessId: ({{TargetProcessId}}) with {{CommandLine}} used to delete backup files."
version: 1.0.0
kind: Scheduled

Stages and Predicates

Stage 1: source

_ASim_ProcessEvent

Stage 2: where

| where TargetProcessFilename has_any ('vssadmin.exe', 'wbadmin.exe', 'wmic.exe')

Stage 3: where

| where CommandLine has_all ('delete', 'shadow')

Stage 4: union

| union isfuzzy=True

Stage 5: source

_ASim_ProcessEvent

Stage 6: where

| where TargetProcessFilename =~ 'bcedit.exe'

Stage 7: where

| where CommandLine has_all ('/set', 'recoveryenabled no')

Stage 8: project

| project
    TimeGenerated,
    DvcHostname,
    DvcIpAddr,
    DvcDomain,
    TargetUsername,
    TargetUsernameType,
    TargetProcessName,
    TargetProcessId,
    CommandLine

Stage 9: extend (4 consecutive steps)

| extend Username = iff(tostring(TargetUsernameType) == 'Windows', tostring(split(TargetUsername, '\\')[1]), TargetUsername)
| extend NTDomain = iff(tostring(TargetUsernameType) == 'Windows', tostring(split(TargetUsername, '\\')[0]), TargetUsername)
| extend Username = iff(tostring(TargetUsernameType) == 'UPN', tostring(split(TargetUsername, '@')[0]), Username)
| extend UPNSuffix = iff(tostring(TargetUsernameType) == 'UPN', tostring(split(TargetUsername, '@')[1]), '')
Username =
ifTargetUsernameType == "Windows"tostring(split(TargetUsername, '\\')[1])
elseTargetUsername

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • /set transforms: term corpus 6 (splunk 5, kusto 1)
  • delete transforms: term corpus 31 (sigma 16, elastic 8, splunk 6, kusto 1)
  • recoveryenabled no transforms: term
  • shadow transforms: term corpus 7 (sigma 3, splunk 2, elastic 1, kusto 1)
field:"CommandLine" kind:match
TargetProcessFilenameeq
  • bcedit.exe
field:"Image" kind:eq value:"bcedit.exe"
TargetProcessFilenamematch
  • vssadmin.exe transforms: term
  • wbadmin.exe transforms: term
  • wmic.exe transforms: term
field:"Image" kind:match

Output fields

These fields are emitted when the rule matches.

FieldSource
CommandLineproject
DvcDomainproject
DvcHostnameproject
DvcIpAddrproject
TargetProcessIdproject
TargetProcessNameproject
TargetUsernameproject
TargetUsernameTypeproject
TimeGeneratedproject
Usernameextend
NTDomainextend
UPNSuffixextend