Query: detection rule: Detects modifications or creations of Windows Defender's default threat action settings based on severity to 'allow' or
Matching passage: Sigma rule: Detects modifications or creations of Windows Defender's default threat action settings based on severity to 'allow' or. Logsource: windows / registry_event. Rule: title: Windows Defender Threat Severity Default Action Modified id: 5a9e1b2c-8f7d-4a1e-9b3c-0f6d7e5a4b1f related: - id: 1e8a9b4d-3c2a-4f9b-8d1e-7c6a5b4f3d2e type: similar status: experimental description: 'Detects modifications or creations of Windows Defender''s default threat action settings based on severity to ''allow'' or take ''no action''. This is a highly suspicious configuration change that effectively disables Defender''s ability to automatically mitigate threats of a certain severity level, allowing malicious software to run unimpeded. An attacker might use this technique to bypass defenses before executing payloads. ' references: - https://learn.microsoft.com/en-us/powershell/module/defender/set-mppreference - https://learn.microsoft.com/en-us/windows-hardware/customize/desktop/unattend/security-malware-windows-defender-threatseveritydefaultaction - https://research.splunk.com/endpoint/7215831c-8252-4ae3-8d43-db588e82f952 - https://gist.github.com/Dump-GUY/8daef859f382b895ac6fd0cf094555d2 - https://thedfirreport.com/2021/10/18/icedid-to-xinglocker-ransomware-in-24-hours/ author: Matt Anderson (Huntress) date: 2025-07-11 tags: - attack.defense-impairment - attack.t1685 logsource: category: registry_event product: windows detection: selection: TargetObject|contains: \Microsoft\Windows Defender\Threats\ThreatSeverityDefaultAction\ TargetObject|endswith: - \1 - \2 - \4 - \5 Details: - DWORD (0x00000006) - DWORD (0x00000009) condition: selection falsepositives: - Legitimate administration via scripts or tools (e.g., SCCM, Intune, GPO enforcement). Correlate with administrative activity. - Software installations that legitimately modify Defender settings (less common for these specific keys). level: high
Near-miss passage: Sigma rule: Detects the execution of "whoami.exe" with the "/FO" flag to choose CSV as output format or with redirection options to. Logsource: windows / process_creation. Rule: title: Whoami.EXE Execution With Output Option id: c30fb093-1109-4dc8-88a8-b30d11c95a5d status: test description: Detects the execution of "whoami.exe" with the "/FO" flag to choose CSV as output format or with redirection options to export the results to a file for later use. references: - https://brica.de/alerts/alert/public/1247926/agent-tesla-keylogger-delivered-inside-a-power-iso-daa-archive/ - https://app.any.run/tasks/7eaba74e-c1ea-400f-9c17-5e30eee89906/ - https://www.youtube.com/watch?v=DsJ9ByX84o4&t=6s author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems) date: 2023-02-28 modified: 2023-12-04 tags: - attack.discovery - attack.t1033 - car.2016-03-001 logsource: category: process_creation product: windows detection: selection_main_img: - Image|endswith: \whoami.exe - OriginalFileName: whoami.exe selection_main_cli: CommandLine|contains: - ' /FO CSV' - ' -FO CSV' selection_special: CommandLine|contains: whoami*> condition: all of selection_main_* or selection_special falsepositives: - Unknown level: medium