Elastic Defend high stable eql

Potential LogonUser API Hooking

Identifies attempts to hook LogonUser API via memory modification. This may indicate an attempt to steal credentials passed for authentication verification via this API.

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Detection Logic

api where process.Ext.api.name in ("WriteProcessMemory", "VirtualProtect") and
 process.Ext.api.metadata.target_address_name like "advapi32.dll!LogonUser*" and process.executable != null and
 not process.thread.Ext.call_stack_final_user_module.name in ("Kernel", "Unknown", "Undetermined") and
 not process.thread.Ext.call_stack_final_user_module.path in ("c:\\windows\\syswow64\\werfault.exe", "c:\\windows\\system32\\werfault.exe") and
 not _arraysearch(process.thread.Ext.call_stack_final_user_module.code_signature, $entry, $entry.trusted == true or $entry.status like "errorCode_endpoint*") and
 process.thread.Ext.call_stack_final_user_module.hash.sha256 != "fdfc853b183d682c912e6487a64dbaea98f8d09207a55d0a512e550c988d6273" and
 not _arraysearch(process.thread.Ext.call_stack, $entry, $entry.symbol_info like "c:\\windows\\system32\\ntdll.dll!LdrLoadDll*") and
 not process.thread.Ext.call_stack_final_user_module.path : 
                              ("?:\\program files\\avg\\antivirus\\aswhook.dll", 
                               "?:\\program files\\avg\\antivirus\\x86\\aswhook.dll", 
                               "?:\\program files\\avast software\\avast\\aswhook.dll",
                               "?:\\program files\\avast software\\avast\\x86\\aswhook.dll",
                               "?:\\windows\\assembly\\nativeimages_*\\microsoft.powershell.commands.management.ni.dll") and 
 not process.executable : ("C:\\Program Files (x86)\\Common Files\\Adobe\\ARM\\1.0\\AdobeARM.exe", 
                           "C:\\Program Files (x86)\\Common Files\\Adobe\\Adobe Desktop Common\\IPCBox\\AdobeIPCBroker.exe", 
                           "C:\\Program Files\\Avast Software\\Browser\\Application\\AvastBrowserProtect.exe")

Field Validations

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