notscimmy / pplib

Elevate a process to be a protected process

pplib - Elevate processes to Protected Processes

This project utilizes executing arbitrary code in the kernel by using libcapcom: https://github.com/notscimmy/libcapcom

Protected Processes

Windows' security model defines that a process running with debug privileges, such as under an administrative account, can request access to any right to other processes running on the machine. Such rights include the ability to:

• Read/write arbitrary process memory
• Inject/execute code
• Control thread states and execution
• Query information about other processes

However, this model conflicts with security requirements for software that requires digital rights management. Protected processes are a solution to this requirement, adding many constraints to the rights that other processes can attain from the operating system. A process becomes a protected process when it's image on disk is signed by a specific Microsoft certificate, or is a process that is part of the Windows Trusted Computer Base (WinTCB). Now the question is, can we trick the operating system to think a process is a protected process, without it being backed by a signed image on disk?

Implementation

The answer is yes, we will achieve this via Direct Kernel Object Manipulation (DKOM). Since behavior of the Win32 API changes based on whether or not rights are being asked for a protected process, it makes sense for the data that distinguishes normal processes from protected processes to live somewhere in the kernel. A look into the EPROCESS structure in WinDbg will reveal a member called PS_PROTECTION Protection which is in fact the data that we want to manipulate.

typedef union _PS_PROTECTION
{
    UCHAR Level;
    struct
    {
        int Type : 3;
        int Audit : 1;
        int Signer : 4;
    } Flags;
} PS_PROTECTION, *PPS_PROTECTION;

typedef enum _PS_PROTECTED_SIGNER
{
    PsProtectedSignerNone = 0,
    PsProtectedSignerAuthenticode = 1,
    PsProtectedSignerCodeGen = 2,
    PsProtectedSignerAntimalware = 3,
    PsProtectedSignerLsa = 4,
    PsProtectedSignerWindows = 5,
    PsProtectedSignerWinTcb = 6,
    PsProtectedSignerMax = 7
} PS_PROTECTED_SIGNER;

typedef enum _PS_PROTECTED_TYPE
{
    PsProtectedTypeNone = 0,
    PsProtectedTypeProtectedLight = 1,
    PsProtectedTypeProtected = 2,
    PsProtectedTypeMax = 3
} PS_PROTECTED_TYPE

The structure is quite simple, and elevating a process to a protected process requires setting the Protection member in the corresponding process' EPROCESS structure to the appropriate bits as defined above.

How to use this library

1. Build the project
2. Link against pplib.lib
3. Include pplib.h
4. Call elevate_ppl()

Inside the testpplib project:

#include <Windows.h>
#include "pplib.h"

int main()
{
    elevate_ppl();
    MessageBoxA(NULL, "Use ProcessHacker to check PPL status", "Paused", NULL);
    return 0;
}