WMI Event Quiz: Master Windows Security with Scheduled Tasks

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Questions and Answers

What does a MOF file do in the context of WMI?

Installs antivirus software

Deletes system logs

Creates a WMI event filter and consumer (correct)

Generates random encryption keys

Which tool can be used to identify WMI event filters and consumers?

Metasploit

Autoruns (correct)

Nmap

Wireshark

What is the purpose of the `Get-WmiObject` PowerShell cmdlet?

To back up system files

To identify and help remove suspicious WMI entries (correct)

To create encryption keys

To capture network traffic

What is the name given to the WMI event filter in the provided MOF file?

GenericFilter Signup and view all the answers

Which query language is used in the event filter specified in the MOF file?

WQL Signup and view all the answers

What is the command line template used by the CommandLineEventConsumer in the MOF file?

C:\windows\evil.exe Signup and view all the answers

What is the purpose of the `#PRAGMA AUTORECOVER` directive in the MOF file?

Ensures the script will recover from errors automatically Signup and view all the answers

Which event is being monitored in the MOF file's event filter?

_InstanceModificationEvent Signup and view all the answers

Which command can be used to schedule tasks on a remote system?

schtasks.exe Signup and view all the answers

In which directory are .job files for scheduled tasks stored in Windows 7?

C:\Windows\System32\Tasks Signup and view all the answers

Which scheduled task utility offers more features and fine control?

schtasks.exe Signup and view all the answers

For which Windows version was a dedicated event log, 'Task Scheduler Operational,' added for logging scheduled tasks?

Windows Vista Signup and view all the answers

Which file records task information in Windows XP?

C:\Windows\Schedlgu.txt Signup and view all the answers

What was the persistence mechanism used by the SUNSPOT malware in the SolarWinds attack?

Scheduled tasks Signup and view all the answers

What type of attacks can remote scheduled tasks aid in?

Credential dumping Signup and view all the answers

Which tool would you use to collect currently scheduled jobs on a Windows system?

Autoruns Signup and view all the answers

What is the percentage range of signed malware according to the McAfee 2019 Threat Report?

1-3% Signup and view all the answers

Which of the following is a benefit of signing malware?

Allows malware to stay hidden longer by being trusted Signup and view all the answers

Why might malware authors avoid signing their malware?

It avoids burning a family of malware if the certificate is revoked Signup and view all the answers

Which of the following strategies is recommended for examining suspicious code?

Initially examining all unsigned code Signup and view all the answers

What percentage of malware samples was typically signed in some quarters?

Less than 1% Signup and view all the answers

What main advantage does signed malware provide for espionage purposes?

Longer undetected presence Signup and view all the answers

Which of the following is NOT a common name for malware?

services.exe Signup and view all the answers

What is a significant drawback of signing malware for rapid development?

Slows down the release process Signup and view all the answers

Which folder is least likely to house malware?

\Documents Signup and view all the answers

Which folder is mentioned as being suspicious for unsigned code?

Windows\System32 folder Signup and view all the answers

What is an example of a common malware tactic to hide its activity?

Process hollowing Signup and view all the answers

Why does the name 'svchost.exe' make for an effective disguise for malware?

It is commonly seen with many instances running Signup and view all the answers

Which location would be suspicious for executable files to run from?

$Recycle.Bin Signup and view all the answers

What feature of a standard Microsoft Windows system contributes to malware's ability to 'hide in plain sight'?

The vast number of files and folders Signup and view all the answers

Which of the following is NOT a common location for malware on Windows systems?

\Users\Public Signup and view all the answers

What tool can provide statistics to help identify trends in malware locations and names?

VirusTotal Signup and view all the answers

What are the three main components needed for setting up a WMI Event Consumer Backdoor?

Event Filter, Event Consumer, Binding Signup and view all the answers

What privilege level do WMI consumers run with?

SYSTEM Signup and view all the answers

What tool can be used to identify and help remove suspicious WMI entries?

Get-WmiObject Signup and view all the answers

Which malware was mentioned as possibly the first to use the WMI Event Consumer Backdoor?

Stuxnet Signup and view all the answers

What is the purpose of the binding component in a WMI Event Consumer backdoor?

To connect the event filter and event consumer Signup and view all the answers

What is a MOF file used for in the context of WMI Event Consumers?

To register new classes into the WMI repository Signup and view all the answers

Which tool was NOT mentioned for setting up WMI Event Consumers?

System Center Configuration Manager Signup and view all the answers

Why is WMI often overlooked by security professionals despite its powerful capabilities?

Because its scope of functionality is not widely recognized Signup and view all the answers

Which PowerShell command can be used to query WMI event filters in the 'root\Subscription' namespace?

Get-WMIObject -Namespace root\Subscription -Class _EventFilter Signup and view all the answers

Why is PowerShell considered an obvious choice for detecting attacks like WMI event consumers?

It provides native support for WMI and easy scalability. Signup and view all the answers

What makes it possible to detect WMI threats without fancy tools?

Basic PowerShell commands Signup and view all the answers

What class should you query with PowerShell to gather WMI event consumers?

_EventConsumer Signup and view all the answers

Which namespace should be queried in addition to 'root\Subscription' to detect WMI event consumers?

root\Default Signup and view all the answers

What is likely the intention behind using non-standard namespaces for WMI event consumers?

Evasion of detection by defenders Signup and view all the answers

When querying WMI classes for detection, what is recommended if you cannot allowlist standard false positives?

Query using a more specific class parameter Signup and view all the answers

Which of the following classes should be queried to bind event filters to consumers?

_FilterToConsumerBinding Signup and view all the answers

What is the main purpose of identifying AutoStart Persistence Locations?

To find programs that start automatically at system boot or user logon. Signup and view all the answers

Which registry key is NOT typically used to automatically start programs when a user logs on?

SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit Signup and view all the answers

Which of the following mechanisms allows a new version of a legitimate DLL to be provided?

DLL Side-Loading Signup and view all the answers

What would be the likely consequence of modifying the Userinit registry key to include a malicious binary?

The malicious binary would execute at boot. Signup and view all the answers

Which of the following describes why the %AppData%\Roaming\Microsoft\Windows\Start Menu\Programs\Startup location is used by attackers?

Creating persistence here does not require administrator rights. Signup and view all the answers

What is the main characteristic of Phantom DLL Hijacking?

Replacing or creating DLLs that applications attempt to load but either don't exist or can be replaced Signup and view all the answers

Which option is not part of the typical DLL search order with SafeDllSearchMode enabled?

Network location Signup and view all the answers

Which AutoStart Persistence Location is located in the file system rather than the registry?

%AppData%\Roaming\Microsoft\Windows\Start Menu\Programs\Startup Signup and view all the answers

What is the significance of the 'run' registry keys according to the content?

They execute items when a user logs on. Signup and view all the answers

What is the known vulnerability related to the Windows desktop Explorer.exe?

Loading an unprotected DLL named ntshrui.dll Signup and view all the answers

Why is analyzing AutoStart data across many systems useful?

To identify potentially compromised systems. Signup and view all the answers

What is a method to discover DLL hijacking attacks?

Performing file system forensic analysis Signup and view all the answers

Which of the following RATs is associated with DLL Side-Loading?

NetTraveler Signup and view all the answers

What is a common use case for the 'RunOnce' registry keys?

To ensure specific tasks run only once at user logon. Signup and view all the answers

Which DLL Hijacking method involves copying susceptible.exe and corresponding bad.dll to a location of choice?

Relative Path DLL Hijacking Signup and view all the answers

Which location is NOT part of the registry?

%AppData%\Roaming\Microsoft\Windows\Start Menu\Programs\Startup Signup and view all the answers

What is the first location checked in the DLL search order on modern systems with SafeDllSearchMode enabled?

DLLs already loaded in memory Signup and view all the answers

What does 'ASEP' stand for in the context of Windows security?

AutoStart Extension Points Signup and view all the answers

What is the main tactic used in phantom DLL hijacking?

Creating a malicious file with the same name as an old DLL and placing it in the search path Signup and view all the answers

What is DLL side-loading typically used to exploit?

Windows side-by-side (SxS) DLL loading mechanism Signup and view all the answers

Which of the following is a characteristic of relative path DLL hijacking?

Involves writing permissions to sensitive folders like Windows\System32 Signup and view all the answers

Which mitigation strategy focuses on the use of signed DLLs?

Validate image dependency integrity Signup and view all the answers

What is the role of AppLocker/Device Guard in mitigating DLL attacks?

It limits where DLLs can be loaded Signup and view all the answers

Why is the SxS functionality vulnerable to abuse?

It allows loading updated DLLs with few validity checks Signup and view all the answers

What does the term 'bring your own executable' refer to in the context of DLL hijacking?

Copying a susceptible executable to a writable location and adding a malicious DLL Signup and view all the answers

Which feature of Microsoft Exploit Protection is mentioned as a limited mitigation?

Validate image dependency integrity Signup and view all the answers

What is the primary reason legitimate binaries are used in attacks?

They can evade security tools and allow-listing Signup and view all the answers

Which binary is used to execute commands and bypass application whitelisting?

Bash.exe Signup and view all the answers

What function does Bitsadmin.exe NOT perform?

Encode Signup and view all the answers

What makes rundll32.exe difficult to detect when used illegitimately?

It requires specific arguments and a DLL function name Signup and view all the answers

Which project collects, categorizes, and provides example usage of legitimate Windows binaries abused by attackers?

LOLBAS Signup and view all the answers

Why has there been an increase in the usage of native Windows tools for malicious purposes?

Host-based security tools have improved in detecting and preventing unsigned malicious code Signup and view all the answers

What is a key indicator that rundll32.exe might be used for malicious purposes?

It executes a DLL from an alternate data stream Signup and view all the answers

What additional information do defenders need to distinguish between legitimate and illegitimate executions of rundll32.exe?

Full command line and arguments Signup and view all the answers

Why are native Windows tools being creatively repurposed by attackers?

To mimic legitimate administrative activities Signup and view all the answers

What specific use case of Certutil.exe is commonly seen?

Downloading files and decoding obfuscated payloads Signup and view all the answers

Study Notes

WMI Event Consumers

WMI allows triggers (filters) to be set that when satisfied will run scripts or executables
Filters can be based on time, service start, user auth, file creation, etc.
PowerShell or mofcomp.exe can be used for setup
The PowerShell cmdlet "Get-WmiObject" can identify and help remove suspicious entries

Scheduled Tasks

Scheduled tasks provide an extremely granular means to create persistence in Windows
at.exe command has long been a core part of the hacker lexicon
at.exe jobs originally ran as SYSTEM regardless of the user's privilege level
The schtasks.exe tool is an upgraded version of at.exe with more features
Remote capabilities are commonly used for lateral movement and credential dumping
SUNSPOT implant used a scheduled task for persistence

Malware Signing

Less than 3% of malware is signed
The number of "New Malicious Signed Binaries" is low compared to total malware
Malware signing is predicted to increase over time
Signed malware is trusted by the operating system and can stay hidden for a longer period
Drawbacks to signing malware include rapid development and release, and code signing certificates being flagged

Adversary Hiding in Plain Sight

Common malware names include svchost.exe, iexplore.exe, explorer.exe, lsass.exe, win.exe, and winlogon.exe
Common malware locations include Temp folders, AppData, $Recycle.Bin, ProgramData, Windows, System32, WinSxS, System Volume Information, and Program Files
Adversaries often use simple names and locations to blend in with legitimate files

WMI Event Consumer Backdoors

WMI Event Consumers are frequently used by malware for persistence
The technique requires three discrete steps: event filter creation, event consumer addition, and binding
PowerShell or mofcomp.exe can be used for setup
Event filters can be set up to trigger immediately upon being registered or via virtually any other Windows event

Using PowerShell to Discover Suspicious WMI Events

PowerShell can be used to discover suspicious WMI events
The PowerShell cmdlet "Get-WmiObject" can identify and help remove suspicious entries

AutoStart Persistence Locations

Programs that start automatically at system boot or user logon
Locations include NTUSER.DAT\Software\Microsoft\Windows\CurrentVersion\Run, SOFTWARE\Microsoft\Windows\CurrentVersion\Runonce, and %AppData%\Roaming\Microsoft\Windows\Start Menu\Programs\Startup

DLL Hijacking Attacks

DLL persistence hijacks attack legitimate and legacy features of the Windows operating system
Search order hijacking is an excellent example
Adversaries can place a malicious DLL in the same folder as the target executable and trump the search order### DLL Hijacking
Place malicious file ahead of DLL in search order to hijack DLL loading
Classic example: Explorer.exe loading bad ntshrui.dll

Phantom DLL Hijacking

Find DLLs that applications attempt to load, but either don't exist or can be replaced
Take advantage of old DLLs that applications still try to load, even when unnecessary
Attackers can create a malicious file with the same name as the old DLL and place it in the search path

DLL Side-Loading

WinSxS mechanism provides a new version of a legit DLL
Attackers can abuse the loading mechanism by creating fake DLLs, using relative paths or other shortcuts
PlugX, NetTraveler, Sakula, Poison Ivy (RATs) are examples of malware that use this technique

Relative Path DLL Hijacking

Copy susceptible.exe and corresponding bad.dll to location of choice
Attackers can write permissions to sensitive folders like Windows and Windows\System32 to achieve this
Alternative approach: copy susceptible executable from a protected folder to a writable location and add a malicious DLL

Living off the Land Binaries (LOLBin)

Legitimate binaries are increasingly used to evade security tools, allow-listing, and hunting
Examples of LOLBin include:
- rundll32.exe "c:\kb4549947:aclui.dll”,DllMain
- At.exe, Atbroker.exe, Bash.exe, Bitsadmin.exe, Certutil.exe
The LOLBAS project collects, categorizes, and provides example usage of LOLBin

Mitigations

Very few viable mitigations for this type of attack
Microsoft Exploit Protection feature “validate image dependency integrity" is limited in functionality
AppLocker/Device Guard can be used to limit where DLLs can be loaded, but this approach is only viable for very locked-down systems

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Learn about Windows security features, including WMI event consumers and scheduled tasks, used to create persistence and detect suspicious entries.

Windows Security: WMI Event Consumers and Scheduled Tasks

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