2/29/2024 0 Comments Applocker policy run from anywhere![]() However it gives us a hint that perhaps some of the enforcement is being done inside the kernel driver. Nothing shocking here, just our rules written out in a security descriptor. Name : APPLICATION PACKAGE AUTHORITY\ALL RESTRICTED APPLICATION PACKAGES Name : APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES Condition: APPID://PATH Contains "%PROGRAMFILES%\*" Condition: APPID://PATH Contains "%WINDIR%\*" Access: Execute|ReadAttributes|ReadControl|Synchronize We might as well start with dumping the Security Descriptor from the file using the Format-AppLockerSecurityDescriptor function from part 3, to check it matches our expectations. We know from the part 1 that there's a policy for DLLs in the DLL.Applocker file. It seems MS doesn't necessarily recommend enabling DLL blocking rules, but we'll dig in anyway as I can't find any official documentation on how it works and it's always interesting to better understand how something works before relying on it. We can try and create the class with DLL enforcement to convince ourselves that's the problem: On a default installation of Windows 10 you should find a single class, "Windows Defender IOfficeAntiVirus implementation" registered which is implemented in the MPOAV DLL. Get-ComCategory -CatId '56FFCC30-D398-11d0-B2AE-00A0C908FA49' | Select -ExpandProperty ClassEntries If you have OleViewDotNet setup (note there are other tools) you can dump all registered classes using the following PowerShell command: You might wonder how is this COM class is registered? An implementor needs to register their COM object with a Category ID of "". And a failure to create the object causes the Save method to fail and the Attachment Services code to automatically delete the file so the browser can't even do anything about it such as ask the user. The implementation for that COM class is in MPOAV.DLL, which as we saw is blocked so the COM object creation fails. When the IAttachmentExecute::Save method is called the file is checked for viruses using the currently registered anti-virus COM object which implements the IOfficeAntiVirus interface. Which is a common interface to verify downloaded files and attachments, apply MOTW and check for viruses. The code was using the Attachment Services API. ![]() Tracking down the resource string for the error lead me to this code. As Chrome is open source it made more sense to look there. As the same failure occurred in both Edge (I didn't test IE) and Chrome it was clearly some common API they were calling. I thought it'd at least be interesting to see why it fails and what MPOAV is doing. of course this is known about (I'm not suggesting otherwise), AaronLocker should allow this DLL by default. This is intentional as you don't want to grant access to locations a normal user could write to, so generally allowing all of %ProgramData% would be asking for trouble. This makes sense, the default rules only permit %WINDOWS% and %PROGRAMFILES% for normal users, however %OSDRIVE%\ProgramData is not allowed. ![]() Use default rule or define new rule conditionįile is signed create a publisher conditionĬreate a path exception to the default rule to exclude \Windows\TempĬ:\Program Files\Woodgrove\HR\Checkcut.exeĬ:\Program Files\Woodgrove\HR\Timesheet.The failing DLL load was for "%OSDRIVE%\PROGRAMDATA\MICROSOFT\WINDOWS DEFENDER\PLATFORM\.4-0\MPOAV.DLL". For info about these settings, see Understanding AppLocker allow and deny actions on rules. In addition, you should now consider whether to allow an app to run or deny permission for it to run. The following table details sample data for documenting rule type and rule condition findings. The types of rule conditions that you will use to create rules, stated in order of preference.Whether your organization will use the built-in default AppLocker rules to allow system files to run.Create a list of apps deployed to each business groupĭocument the following items for each business group or organizational unit:. ![]() Determine your application control objectives.To complete this AppLocker planning document, you should first complete the following steps: This topic describes what AppLocker rule conditions to associate with each file, how to associate these rule conditions, the source of the rule, and whether the file should be included or excluded. Learn more about the Windows Defender Application Control feature availability. Some capabilities of Windows Defender Application Control are only available on specific Windows versions.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |