Microsoft Windows Defender Tampering

  1[metadata]
  2creation_date = "2021/10/18"
  3integration = ["endpoint", "windows", "m365_defender", "sentinel_one_cloud_funnel"]
  4maturity = "production"
  5updated_date = "2024/10/15"
  6min_stack_version = "8.14.0"
  7min_stack_comments = "Breaking change at 8.14.0 for the Windows Integration."
  8
  9[rule]
 10author = ["Austin Songer"]
 11description = """
 12Identifies when one or more features on Microsoft Defender are disabled. Adversaries may disable or tamper with
 13Microsoft Defender features to evade detection and conceal malicious behavior.
 14"""
 15false_positives = ["Legitimate Windows Defender configuration changes"]
 16from = "now-9m"
 17index = [
 18    "winlogbeat-*",
 19    "logs-endpoint.events.registry-*",
 20    "logs-windows.sysmon_operational-*",
 21    "logs-m365_defender.event-*",
 22    "logs-sentinel_one_cloud_funnel.*",
 23    "endgame-*"
 24]
 25language = "eql"
 26license = "Elastic License v2"
 27name = "Microsoft Windows Defender Tampering"
 28note = """## Triage and analysis
 29
 30### Investigating Microsoft Windows Defender Tampering
 31
 32Microsoft Windows Defender is an antivirus product built into Microsoft Windows, which makes it popular across multiple environments. Disabling it is a common step in threat actor playbooks.
 33
 34This rule monitors the registry for modifications that disable Windows Defender features.
 35
 36#### Possible investigation steps
 37
 38- Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
 39- Validate the activity is not related to planned patches, updates, network administrator activity, or legitimate software installations.
 40- Identify the user account that performed the action and whether it should perform this kind of action.
 41- Contact the account owner and confirm whether they are aware of this activity.
 42- Investigate other alerts associated with the user/host during the past 48 hours.
 43- Examine which features have been disabled, and check if this operation is done under change management and approved according to the organization's policy.
 44
 45### False positive analysis
 46
 47- This mechanism can be used legitimately. Analysts can dismiss the alert if the administrator is aware of the activity, the configuration is justified (for example, it is being used to deploy other security solutions or troubleshooting), and no other suspicious activity has been observed.
 48
 49### Related rules
 50
 51- Windows Defender Disabled via Registry Modification - 2ffa1f1e-b6db-47fa-994b-1512743847eb
 52- Disabling Windows Defender Security Settings via PowerShell - c8cccb06-faf2-4cd5-886e-2c9636cfcb87
 53
 54### Response and remediation
 55
 56- Initiate the incident response process based on the outcome of the triage.
 57- Isolate the involved hosts to prevent further post-compromise behavior.
 58- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business systems, and web services.
 59- Take actions to restore the appropriate Windows Defender antivirus configurations.
 60- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
 61- Review the privileges assigned to the user to ensure that the least privilege principle is being followed.
 62- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
 63- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the mean time to respond (MTTR).
 64"""
 65references = [
 66    "https://thedfirreport.com/2021/10/18/icedid-to-xinglocker-ransomware-in-24-hours/",
 67    "https://www.tenforums.com/tutorials/32236-enable-disable-microsoft-defender-pua-protection-windows-10-a.html",
 68    "https://www.tenforums.com/tutorials/104025-turn-off-core-isolation-memory-integrity-windows-10-a.html",
 69    "https://www.tenforums.com/tutorials/105533-enable-disable-windows-defender-exploit-protection-settings.html",
 70    "https://www.tenforums.com/tutorials/123792-turn-off-tamper-protection-microsoft-defender-antivirus.html",
 71    "https://www.tenforums.com/tutorials/51514-turn-off-microsoft-defender-periodic-scanning-windows-10-a.html",
 72    "https://www.tenforums.com/tutorials/3569-turn-off-real-time-protection-microsoft-defender-antivirus.html",
 73    "https://www.tenforums.com/tutorials/99576-how-schedule-scan-microsoft-defender-antivirus-windows-10-a.html",
 74    "https://www.elastic.co/security-labs/invisible-miners-unveiling-ghostengine",
 75]
 76risk_score = 47
 77rule_id = "fe794edd-487f-4a90-b285-3ee54f2af2d3"
 78severity = "medium"
 79tags = [
 80    "Domain: Endpoint",
 81    "OS: Windows",
 82    "Use Case: Threat Detection",
 83    "Tactic: Defense Evasion",
 84    "Resources: Investigation Guide",
 85    "Data Source: Elastic Defend",
 86    "Data Source: Sysmon",
 87    "Data Source: Microsoft Defender for Endpoint",
 88    "Data Source: SentinelOne",
 89    "Data Source: Elastic Endgame",
 90]
 91timestamp_override = "event.ingested"
 92type = "eql"
 93
 94query = '''
 95registry where host.os.type == "windows" and event.type == "change" and process.executable != null and
 96  (
 97    (
 98      registry.value : (
 99        "PUAProtection", "DisallowExploitProtectionOverride", "TamperProtection", "EnableControlledFolderAccess",
100        "SpynetReporting", "SubmitSamplesConsent"
101      ) and registry.data.strings : ("0", "0x00000000")
102    ) or
103    (
104      registry.path : (
105        "DisableAntiSpyware", "DisableRealtimeMonitoring", "DisableIntrusionPreventionSystem", "DisableScriptScanning",
106        "DisableIOAVProtection", "DisableEnhancedNotifications", "DisableBlockAtFirstSeen", "DisableBehaviorMonitoring"
107      ) and registry.data.strings : ("1", "0x00000001")
108    )
109  ) and
110  not process.executable : (
111    "?:\\Windows\\system32\\svchost.exe", 
112    "?:\\Windows\\CCM\\CcmExec.exe", 
113    "?:\\Windows\\System32\\DeviceEnroller.exe", 
114    "?:\\Program Files (x86)\\Trend Micro\\Security Agent\\tmuninst.exe"
115  )
116
117/*
118    Full registry key paths omitted due to data source variations:
119    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\DisableAntiSpyware"
120    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableRealtimeMonitoring"
121    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableIntrusionPreventionSystem"
122    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableScriptScanning"
123    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableIOAVProtection"
124    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Reporting\\DisableEnhancedNotifications"
125    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\SpyNet\\DisableBlockAtFirstSeen"
126    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableBehaviorMonitoring"
127    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\PUAProtection"
128    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender Security Center\\App and Browser protection\\DisallowExploitProtectionOverride"
129    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Features\\TamperProtection"
130    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Windows Defender Exploit Guard\\Controlled Folder Access\\EnableControlledFolderAccess"
131    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\SpyNet\\SpynetReporting"
132    "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\SpyNet\\SubmitSamplesConsent"
133*/
134'''
135
136
137[[rule.threat]]
138framework = "MITRE ATT&CK"
139[[rule.threat.technique]]
140id = "T1112"
141name = "Modify Registry"
142reference = "https://attack.mitre.org/techniques/T1112/"
143
144[[rule.threat.technique]]
145id = "T1562"
146name = "Impair Defenses"
147reference = "https://attack.mitre.org/techniques/T1562/"
148
149
150[rule.threat.tactic]
151id = "TA0005"
152name = "Defense Evasion"
153reference = "https://attack.mitre.org/tactics/TA0005/"