The hypothesis is that an adversary is attempting to modify or access private user profiles to gain unauthorized access or persist within the environment. A SOC team should proactively hunt for this behavior in Azure Sentinel to identify potential lateral movement or privilege escalation attempts that may evade traditional detection methods.
YARA Rule
rule win_private_profile {
meta:
author = "x0r"
description = "Affect private profile"
version = "0.1"
strings:
$f1 = "kernel32.dll" nocase
$c1 = "GetPrivateProfileIntA"
$c2 = "GetPrivateProfileStringA"
$c3 = "WritePrivateProfileStringA"
condition:
$f1 and 1 of ($c*)
}
This YARA rule can be deployed in the following contexts:
This rule contains 4 string patterns in its detection logic.
Scenario: System Update via Windows Update
Description: A Windows Update process may modify private profile files (e.g., NTUSER.DAT) during system configuration changes.
Filter/Exclusion: Check for ProcessName = "wuauclt.exe" or CommandLine contains "wuauclt.exe" in the event log.
Scenario: User Profile Synchronization via Group Policy
Description: Group Policy Preferences (GPP) may synchronize user profiles, which can trigger changes to private profile files.
Filter/Exclusion: Filter events where ProcessName = "gpupdate.exe" or CommandLine contains "gpupdate".
Scenario: Scheduled Task for User Profile Backup
Description: A scheduled task configured to back up user profiles may modify or access private profile files.
Filter/Exclusion: Exclude events where ProcessName = "schtasks.exe" or CommandLine contains "schtasks".
Scenario: User Profile Migration via Roaming Profiles
Description: Roaming profile migration across domain controllers may involve copying or modifying private profile files.
Filter/Exclusion: Filter events where ProcessName = "net.exe" or CommandLine contains "net use" or "net logon".
Scenario: Antivirus or Endpoint Protection Scan
Description: Antivirus tools like Microsoft Defender or third-party solutions may scan or modify private profile files during a full system scan.
Filter/Exclusion: Exclude events where ProcessName = "MsMpEng.exe" or ProcessName = "Mcshield.exe" (for McAfee).