Signed Binary Proxy Execution: Control Panel

Adversaries may abuse control.exe to proxy execution of malicious payloads. The Windows Control Panel process binary (control.exe) handles execution of Control Panel items, which are utilities that allow users to view and adjust computer settings.

Control Panel items are registered executable (.exe) or Control Panel (.cpl) files, the latter are actually renamed dynamic-link library (.dll) files that export a CPlApplet function.[1][2] For ease of use, Control Panel items typically include graphical menus available to users after being registered and loaded into the Control Panel.[1] Control Panel items can be executed directly from the command line, programmatically via an application programming interface (API) call, or by simply double-clicking the file.[1] [2][3]

Malicious Control Panel items can be delivered via Phishing campaigns[2][3] or executed as part of multi-stage malware.[4] Control Panel items, specifically CPL files, may also bypass application and/or file extension allow lists.

Adversaries may also rename malicious DLL files (.dll) with Control Panel file extensions (.cpl) and register them to HKCU\Software\Microsoft\Windows\CurrentVersion\Control Panel\Cpls. Even when these registered DLLs do not comply with the CPL file specification and do not export CPlApplet functions, they are loaded and executed through its DllEntryPoint when Control Panel is executed. CPL files not exporting CPlApplet are not directly executable.[5]

ID: T1218.002
Sub-technique of:  T1218
Tactic: Defense Evasion
Platforms: Windows
Permissions Required: Administrator, SYSTEM, User
Defense Bypassed: Application control
Contributors: ESET
Version: 1.1
Created: 23 January 2020
Last Modified: 21 October 2020
Provided by LAYER 8

Procedure Examples

ID Name Description
S0260 InvisiMole

InvisiMole can register itself for execution and persistence via the Control Panel.[5]

S0172 Reaver

Reaver drops and executes a malicious CPL file as its payload.[4]

Mitigations

ID Mitigation Description
M1038 Execution Prevention

Identify and block potentially malicious and unknown .cpl files by using application control [6] tools, like Windows Defender Application Control[7], AppLocker, [8] [9] or Software Restriction Policies [10] where appropriate. [11]

M1022 Restrict File and Directory Permissions

Restrict storage and execution of Control Panel items to protected directories, such as C:\Windows, rather than user directories.

Detection

ID Data Source Data Component
DS0017 Command Command Execution
DS0022 File File Creation
DS0011 Module Module Load
DS0009 Process OS API Execution
Process Creation
DS0024 Windows Registry Windows Registry Key Modification

Monitor and analyze activity related to items associated with CPL files, such as the control.exe and the Control_RunDLL and ControlRunDLLAsUser API functions in shell32.dll. When executed from the command line or clicked, control.exe will execute the CPL file (ex: control.exe file.cpl) before Rundll32 is used to call the CPL's API functions (ex: rundll32.exe shell32.dll,Control_RunDLL file.cpl). CPL files can be executed directly via the CPL API function with just the latter Rundll32 command, which may bypass detections and/or execution filters for control.exe.[2]

Inventory Control Panel items to locate unregistered and potentially malicious files present on systems:

  • Executable format registered Control Panel items will have a globally unique identifier (GUID) and registration Registry entries in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ControlPanel\NameSpace and HKEY_CLASSES_ROOT\CLSID{{GUID}}. These entries may contain information about the Control Panel item such as its display name, path to the local file, and the command executed when opened in the Control Panel. [1]
  • CPL format registered Control Panel items stored in the System32 directory are automatically shown in the Control Panel. Other Control Panel items will have registration entries in the CPLs and Extended Properties Registry keys of HKEY_LOCAL_MACHINE or HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Control Panel. These entries may include information such as a GUID, path to the local file, and a canonical name used to launch the file programmatically ( WinExec("c:\windows\system32\control.exe {{Canonical_Name}}", SW_NORMAL);) or from a command line (control.exe /name {{Canonical_Name}}).[1]
  • Some Control Panel items are extensible via Shell extensions registered in HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Controls Folder{{name}}\Shellex\PropertySheetHandlers where {{name}} is the predefined name of the system item.[1]

Analyze new Control Panel items as well as those present on disk for malicious content. Both executable and CPL formats are compliant Portable Executable (PE) images and can be examined using traditional tools and methods, pending anti-reverse-engineering techniques.[2]

References