remcos_evasion

detections/endpoint/add_or_set_windows_defender_exclusion.yml

@@ -0,0 +1,75 @@
+name: Add or Set Windows Defender Exclusion
+id: 773b66fe-4dd9-11ec-8289-acde48001122
+version: 1
+date: '2021-11-25'
+author: Teoderick Contreras, Splunk
+type: TTP
+datamodel:
+- Endpoint
+description: This analytic will detect a suspicious process commandline related to windows defender exclusion feature. 
+  This command is abused by adversaries, malware author and red teams to bypassed Windows Defender Anti-Virus product 
+  by excluding  folder path, file path, process, extensions and etc. from its real time or schedule scan to execute their malicious code. 
+  This is a good indicator for defense evasion and to look further for events after this behavior.
+search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
+  as lastTime from datamodel=Endpoint.Processes where (Processes.process = "*Add-MpPreference *" OR Processes.process = "*Set-MpPreference *") 
+  AND Processes.process="*-exclusion*"  
+  by Processes.dest Processes.user Processes.parent_process Processes.parent_process_name Processes.process_name Processes.original_file_name 
+  Processes.process Processes.process_id Processes.parent_process_id 
+  | `drop_dm_object_name(Processes)`
+  | `security_content_ctime(firstTime)` 
+  | `security_content_ctime(lastTime)`
+  | `add_or_set_windows_defender_exclusion_filter`'
+how_to_implement: To successfully implement this search you need to be ingesting information
+  on process that include the name of the process responsible for the changes from
+  your endpoints into the `Endpoint` datamodel in the `Registry` node. Also make sure
+  that this registry was included in your config files ex. sysmon config to be monitored.
+known_false_positives: admin or user may choose to use this windows features.
+references:
+- https://tccontre.blogspot.com/2020/01/remcos-rat-evading-windows-defender-av.html
+- https://app.any.run/tasks/cf1245de-06a7-4366-8209-8e3006f2bfe5/
+tags:
+  analytic_story:
+  - Remcos
+  - Windows Defense Evasion Tactics
+  dataset:
+  - https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1562.001/defender_exclusion_sysmon/sysmon.log
+  kill_chain_phases:
+  - Exploitation
+  mitre_attack_id:
+  - T1562.001
+  - T1562
+  product:
+  - Splunk Enterprise
+  - Splunk Enterprise Security
+  - Splunk Cloud
+  required_fields:
+  - _time
+  - Processes.dest
+  - Processes.user
+  - Processes.parent_process_name
+  - Processes.parent_process
+  - Processes.original_file_name
+  - Processes.process_name
+  - Processes.process
+  - Processes.process_id
+  - Processes.parent_process_path
+  - Processes.process_path
+  - Processes.parent_process_id
+  security_domain: endpoint
+  impact: 80
+  confidence: 80
+  # (impact * confidence)/100
+  risk_score: 64
+  context:
+  - Source:Endpoint
+  - Stage:Defense Evasion
+  message: exclusion command $process$ executed on $dest$
+  observable:
+  - name: user
+    type: User
+    role:
+    - Victim
+  - name: dest
+    type: Hostname
+    role:
+    - Victim

detections/endpoint/powershell_windows_defender_exclusion_commands.yml

@@ -0,0 +1,65 @@
+name: Powershell Windows Defender Exclusion Commands
+id: 907ac95c-4dd9-11ec-ba2c-acde48001122
+version: 1
+date: '2021-11-25'
+author: Teoderick Contreras, Splunk
+type: TTP
+datamodel:
+- Endpoint
+description: This analytic will detect a suspicious process commandline related to windows defender exclusion feature. 
+  This command is abused by adversaries, malware author and red teams to bypassed Windows Defender Anti-Virus product 
+  by excluding  folder path, file path, process, extensions and etc. from its real time or schedule scan to execute their malicious code. 
+  This is a good indicator for defense evasion and to look further for events after this behavior.
+search: '`powershell` EventCode=4104 (Message = "*Add-MpPreference *" OR Message = "*Set-MpPreference *") AND Message = "*-exclusion*" 
+  | stats count min(_time) as firstTime max(_time) as lastTime by EventCode Message ComputerName User 
+  | `security_content_ctime(firstTime)` 
+  | `security_content_ctime(lastTime)`
+  | `powershell_windows_defender_exclusion_commands_filter`'
+how_to_implement: To successfully implement this search you need to be ingesting information
+  on process that include the name of the process responsible for the changes from
+  your endpoints into the `Endpoint` datamodel in the `Registry` node. Also make sure
+  that this registry was included in your config files ex. sysmon config to be monitored.
+known_false_positives: admin or user may choose to use this windows features.
+references:
+- https://tccontre.blogspot.com/2020/01/remcos-rat-evading-windows-defender-av.html
+- https://app.any.run/tasks/cf1245de-06a7-4366-8209-8e3006f2bfe5/
+tags:
+  analytic_story:
+  - Remcos
+  - Windows Defense Evasion Tactics
+  dataset:
+  - UPDATE_DATASET_URL
+  kill_chain_phases:
+  - Exploitation
+  mitre_attack_id:
+  - T1562.001
+  - T1562
+  product:
+  - Splunk Enterprise
+  - Splunk Enterprise Security
+  - Splunk Cloud
+  required_fields:
+  - _time
+  - EventCode
+  - Message
+  - ComputerName
+  - User
+  security_domain: endpoint
+  impact: 80
+  confidence: 80
+  # (impact * confidence)/100
+  risk_score: 64
+  context:
+  - Source:Endpoint
+  - Stage:Defense Evasion
+  message: exclusion command $Message$ executed on $ComputerName$
+  observable:
+  - name: User
+    type: User
+    role:
+    - Victim
+  - name: ComputerName
+    type: Hostname
+    role:
+    - Victim
+  

detections/endpoint/windows_defender_exclusion_registry_entry.yml

@@ -0,0 +1,68 @@
+name: Windows Defender Exclusion Registry Entry
+id: 13395a44-4dd9-11ec-9df7-acde48001122
+version: 1
+date: '2021-11-25'
+author: Teoderick Contreras, Splunk
+type: TTP
+datamodel:
+- Endpoint
+description: This analytic will detect a suspicious process that modify a registry related to windows defender exclusion feature. 
+  This registry is abused by adversaries, malware author and red teams to bypassed Windows Defender Anti-Virus product 
+  by excluding folder path, file path, process, extensions and etc. from its real time or schedule scan to execute their malicious code. 
+  This is a good indicator for a defense evasion and to look further for events after this behavior.
+search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
+  as lastTime from datamodel=Endpoint.Registry where Registry.registry_path = "*\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Exclusions\\*"  
+  by Registry.dest Registry.user Registry.registry_path Registry.registry_value_name Registry.registry_value_data | `drop_dm_object_name(Registry)`
+  | `security_content_ctime(lastTime)` 
+  | `security_content_ctime(firstTime)`
+  | `windows_defender_exclusion_registry_entry_filter`'
+how_to_implement: To successfully implement this search you need to be ingesting information
+  on process that include the name of the process responsible for the changes from
+  your endpoints into the `Endpoint` datamodel in the `Registry` node. Also make sure
+  that this registry was included in your config files ex. sysmon config to be monitored.
+known_false_positives: admin or user may choose to use this windows features.
+references:
+- https://tccontre.blogspot.com/2020/01/remcos-rat-evading-windows-defender-av.html
+- https://app.any.run/tasks/cf1245de-06a7-4366-8209-8e3006f2bfe5/
+tags:
+  analytic_story:
+  - Remcos
+  - Windows Defense Evasion Tactics
+  dataset:
+  - https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1562.001/defender_exclusion_sysmon/sysmon.log
+  kill_chain_phases:
+  - Exploitation
+  mitre_attack_id:
+  - T1562.001
+  - T1562
+  product:
+  - Splunk Enterprise
+  - Splunk Enterprise Security
+  - Splunk Cloud
+  required_fields:
+  - _time
+  - Registry.registry_key_name
+  - Registry.registry_path
+  - Registry.user
+  - Registry.dest
+  - Registry.registry_value_name
+  - Registry.registry_value_data
+  security_domain: endpoint
+  impact: 80
+  confidence: 80
+  # (impact * confidence)/100
+  risk_score: 64
+  context:
+  - Source:Endpoint
+  - Stage:Defense Evasion
+  message: exclusion registry $registry_path$  modified or added on $dest$
+  observable:
+  - name: user
+    type: User
+    role:
+    - Victim
+  - name: dest
+    type: Hostname
+    role:
+    - Victim
+  

tests/endpoint/add_or_set_windows_defender_exclusion.test.yml

@@ -0,0 +1,12 @@
+name: Add or Set Windows Defender Exclusion Unit Test
+tests:
+- name: Add or Set Windows Defender Exclusion
+  file: endpoint/add_or_set_windows_defender_exclusion.yml
+  pass_condition: '| stats count | where count > 0'
+  earliest_time: '-24h'
+  latest_time: 'now'
+  attack_data:
+  - file_name: sysmon.log
+    data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1562.001/defender_exclusion_sysmon/sysmon.log
+    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
+    sourcetype: xmlwineventlog

tests/endpoint/powershell_windows_defender_exclusion_commands.test.yml

@@ -0,0 +1,12 @@
+name: Powershell Windows Defender Exclusion Commands Unit Test
+tests:
+- name: Powershell Windows Defender Exclusion Commands
+  file: endpoint/powershell_windows_defender_exclusion_commands.yml
+  pass_condition: '| stats count | where count > 0'
+  earliest_time: '-24h'
+  latest_time: 'now'
+  attack_data:
+  - file_name: powershell.log
+    data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1562.001/defender_exclusion_powershell/powershell.log
+    source: WinEventLog:Microsoft-Windows-PowerShell/Operational
+    sourcetype: WinEventLog

tests/endpoint/windows_defender_exclusion_registry_entry.test.yml

@@ -0,0 +1,12 @@
+name: Windows Defender Exclusion Registry Entry Unit Test
+tests:
+- name: Windows Defender Exclusion Registry Entry
+  file: endpoint/windows_defender_exclusion_registry_entry.yml
+  pass_condition: '| stats count | where count > 0'
+  earliest_time: '-24h'
+  latest_time: 'now'
+  attack_data:
+  - file_name: sysmon.log
+    data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1562.001/defender_exclusion_sysmon/sysmon.log
+    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
+    sourcetype: xmlwineventlog