Microsoft Windows Defender Tampering

  1[metadata]
  2creation_date = "2021/10/18"
  3integration = ["endpoint", "windows"]
  4maturity = "production"
  5min_stack_comments = "New fields added: required_fields, related_integrations, setup"
  6min_stack_version = "8.3.0"
  7updated_date = "2024/03/28"
  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 = ["winlogbeat-*", "logs-endpoint.events.registry-*", "logs-windows.sysmon_operational-*"]
 18language = "eql"
 19license = "Elastic License v2"
 20name = "Microsoft Windows Defender Tampering"
 21note = """## Triage and analysis
 22
 23### Investigating Microsoft Windows Defender Tampering
 24
 25Microsoft 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.
 26
 27This rule monitors the registry for modifications that disable Windows Defender features.
 28
 29#### Possible investigation steps
 30
 31- 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.
 32- Validate the activity is not related to planned patches, updates, network administrator activity, or legitimate software installations.
 33- Identify the user account that performed the action and whether it should perform this kind of action.
 34- Contact the account owner and confirm whether they are aware of this activity.
 35- Investigate other alerts associated with the user/host during the past 48 hours.
 36- Examine which features have been disabled, and check if this operation is done under change management and approved according to the organization's policy.
 37
 38### False positive analysis
 39
 40- 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.
 41
 42### Related rules
 43
 44- Windows Defender Disabled via Registry Modification - 2ffa1f1e-b6db-47fa-994b-1512743847eb
 45- Disabling Windows Defender Security Settings via PowerShell - c8cccb06-faf2-4cd5-886e-2c9636cfcb87
 46
 47### Response and remediation
 48
 49- Initiate the incident response process based on the outcome of the triage.
 50- Isolate the involved hosts to prevent further post-compromise behavior.
 51- 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.
 52- Take actions to restore the appropriate Windows Defender antivirus configurations.
 53- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
 54- Review the privileges assigned to the user to ensure that the least privilege principle is being followed.
 55- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
 56- 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).
 57"""
 58references = [
 59    "https://thedfirreport.com/2021/10/18/icedid-to-xinglocker-ransomware-in-24-hours/",
 60    "https://www.tenforums.com/tutorials/32236-enable-disable-microsoft-defender-pua-protection-windows-10-a.html",
 61    "https://www.tenforums.com/tutorials/104025-turn-off-core-isolation-memory-integrity-windows-10-a.html",
 62    "https://www.tenforums.com/tutorials/105533-enable-disable-windows-defender-exploit-protection-settings.html",
 63    "https://www.tenforums.com/tutorials/123792-turn-off-tamper-protection-microsoft-defender-antivirus.html",
 64    "https://www.tenforums.com/tutorials/51514-turn-off-microsoft-defender-periodic-scanning-windows-10-a.html",
 65    "https://www.tenforums.com/tutorials/3569-turn-off-real-time-protection-microsoft-defender-antivirus.html",
 66    "https://www.tenforums.com/tutorials/99576-how-schedule-scan-microsoft-defender-antivirus-windows-10-a.html",
 67]
 68risk_score = 47
 69rule_id = "fe794edd-487f-4a90-b285-3ee54f2af2d3"
 70setup = """## Setup
 71
 72If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2,
 73events will not define `event.ingested` and default fallback for EQL rules was not added until version 8.2.
 74Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate
 75`event.ingested` to @timestamp.
 76For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html
 77"""
 78severity = "medium"
 79tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Defense Evasion", "Resources: Investigation Guide", "Data Source: Elastic Defend", "Data Source: Sysmon"]
 80timestamp_override = "event.ingested"
 81type = "eql"
 82
 83query = '''
 84registry where host.os.type == "windows" and event.type in ("creation", "change") and
 85  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\PUAProtection" and
 86  registry.data.strings : ("0", "0x00000000")) or
 87  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender Security Center\\App and Browser protection\\DisallowExploitProtectionOverride" and
 88  registry.data.strings : ("0", "0x00000000")) or
 89  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\DisableAntiSpyware" and
 90  registry.data.strings : ("1", "0x00000001")) or
 91  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Features\\TamperProtection" and
 92  registry.data.strings : ("0", "0x00000000")) or
 93  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableRealtimeMonitoring" and
 94  registry.data.strings : ("1", "0x00000001")) or
 95  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableIntrusionPreventionSystem" and
 96  registry.data.strings : ("1", "0x00000001")) or
 97  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableScriptScanning" and
 98  registry.data.strings : ("1", "0x00000001")) or
 99  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Windows Defender Exploit Guard\\Controlled Folder Access\\EnableControlledFolderAccess" and
100  registry.data.strings : ("0", "0x00000000")) or
101  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableIOAVProtection" and
102  registry.data.strings : ("1", "0x00000001")) or
103  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Reporting\\DisableEnhancedNotifications" and
104  registry.data.strings : ("1", "0x00000001")) or
105  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\SpyNet\\DisableBlockAtFirstSeen" and
106  registry.data.strings : ("1", "0x00000001")) or
107  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\SpyNet\\SpynetReporting" and
108  registry.data.strings : ("0", "0x00000000")) or
109  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\SpyNet\\SubmitSamplesConsent" and
110  registry.data.strings : ("0", "0x00000000")) or
111  (registry.path : "HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows Defender\\Real-Time Protection\\DisableBehaviorMonitoring" and
112  registry.data.strings : ("1", "0x00000001"))
113'''
114
115
116[[rule.threat]]
117framework = "MITRE ATT&CK"
118[[rule.threat.technique]]
119id = "T1562"
120name = "Impair Defenses"
121reference = "https://attack.mitre.org/techniques/T1562/"
122
123[[rule.threat.technique]]
124id = "T1112"
125name = "Modify Registry"
126reference = "https://attack.mitre.org/techniques/T1112/"
127
128[rule.threat.tactic]
129id = "TA0005"
130name = "Defense Evasion"
131reference = "https://attack.mitre.org/tactics/TA0005/"