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api: elevate rundll32 calls to SYSTEM

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I need this for debugging. In production environment, WoW64 clients will
already call rundll32 elevated to SYSTEM.

Signed-off-by: Simon Rozman <simon@rozman.si>
This commit is contained in:
Simon Rozman 2020-10-15 14:54:21 +02:00 committed by Jason A. Donenfeld
parent ac6db7788a
commit 369801cdfa
2 changed files with 99 additions and 0 deletions
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1
api/pch.h
View File

@ -28,4 +28,5 @@
#include <SetupAPI.h>
#include <Shlwapi.h>
#include <string.h>
#include <TlHelp32.h>
#include <wchar.h>

98
api/rundll32.c
View File

@ -7,6 +7,100 @@
#if defined(_M_AMD64) || defined(_M_ARM64)
static BOOL ElevateToSystem(VOID)
{
HANDLE CurrentProcessToken, ThreadToken, ProcessSnapshot, WinlogonProcess, WinlogonToken, DuplicatedToken;
PROCESSENTRY32W ProcessEntry = { .dwSize = sizeof(PROCESSENTRY32W) };
BOOL Ret;
DWORD LastError = ERROR_SUCCESS;
TOKEN_PRIVILEGES Privileges = { .PrivilegeCount = 1, .Privileges = { { .Attributes = SE_PRIVILEGE_ENABLED } } };
CHAR LocalSystemSid[0x400];
DWORD RequiredBytes = sizeof(LocalSystemSid);
struct
{
TOKEN_USER MaybeLocalSystem;
CHAR LargeEnoughForLocalSystem[0x400];
} TokenUserBuffer;
Ret = CreateWellKnownSid(WinLocalSystemSid, NULL, &LocalSystemSid, &RequiredBytes);
LastError = GetLastError();
if (!Ret)
goto cleanup;
Ret = OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &CurrentProcessToken);
LastError = GetLastError();
if (!Ret)
goto cleanup;
Ret =
GetTokenInformation(CurrentProcessToken, TokenUser, &TokenUserBuffer, sizeof(TokenUserBuffer), &RequiredBytes);
LastError = GetLastError();
CloseHandle(CurrentProcessToken);
if (!Ret)
goto cleanup;
if (EqualSid(TokenUserBuffer.MaybeLocalSystem.User.Sid, LocalSystemSid))
return TRUE;
Ret = LookupPrivilegeValueW(NULL, SE_DEBUG_NAME, &Privileges.Privileges[0].Luid);
LastError = GetLastError();
if (!Ret)
goto cleanup;
ProcessSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
LastError = GetLastError();
if (ProcessSnapshot == INVALID_HANDLE_VALUE)
goto cleanup;
for (Ret = Process32FirstW(ProcessSnapshot, &ProcessEntry); Ret;
Ret = Process32NextW(ProcessSnapshot, &ProcessEntry))
{
if (_wcsicmp(ProcessEntry.szExeFile, L"winlogon.exe"))
continue;
RevertToSelf();
Ret = ImpersonateSelf(SecurityImpersonation);
LastError = GetLastError();
if (!Ret)
continue;
Ret = OpenThreadToken(GetCurrentThread(), TOKEN_ADJUST_PRIVILEGES, FALSE, &ThreadToken);
LastError = GetLastError();
if (!Ret)
continue;
Ret = AdjustTokenPrivileges(ThreadToken, FALSE, &Privileges, sizeof(Privileges), NULL, NULL);
LastError = GetLastError();
CloseHandle(ThreadToken);
if (!Ret)
continue;
WinlogonProcess = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, ProcessEntry.th32ProcessID);
LastError = GetLastError();
if (!WinlogonProcess)
continue;
Ret = OpenProcessToken(WinlogonProcess, TOKEN_IMPERSONATE | TOKEN_DUPLICATE, &WinlogonToken);
LastError = GetLastError();
CloseHandle(WinlogonProcess);
if (!Ret)
continue;
Ret = DuplicateToken(WinlogonToken, SecurityImpersonation, &DuplicatedToken);
LastError = GetLastError();
CloseHandle(WinlogonToken);
if (!Ret)
continue;
if (!GetTokenInformation(DuplicatedToken, TokenUser, &TokenUserBuffer, sizeof(TokenUserBuffer), &RequiredBytes))
goto next;
if (SetLastError(ERROR_ACCESS_DENIED), !EqualSid(TokenUserBuffer.MaybeLocalSystem.User.Sid, LocalSystemSid))
goto next;
if (!SetThreadToken(NULL, DuplicatedToken))
goto next;
CloseHandle(DuplicatedToken);
CloseHandle(ProcessSnapshot);
SetLastError(ERROR_SUCCESS);
return TRUE;
next:
LastError = GetLastError();
CloseHandle(DuplicatedToken);
}
RevertToSelf();
CloseHandle(ProcessSnapshot);
cleanup:
SetLastError(LastError);
return FALSE;
}
__declspec(dllexport) VOID __stdcall CreateAdapter(HWND hwnd, HINSTANCE hinst, LPSTR lpszCmdLine, int nCmdShow)
{
UNREFERENCED_PARAMETER(hwnd);
@ -28,7 +122,9 @@ __declspec(dllexport) VOID __stdcall CreateAdapter(HWND hwnd, HINSTANCE hinst, L
goto cleanupArgv;
WINTUN_ADAPTER *Adapter;
BOOL RebootRequired = FALSE;
ElevateToSystem();
DWORD Result = WintunCreateAdapter(Argv[2], Argv[3], Argc > 4 ? &RequestedGUID : NULL, &Adapter, &RebootRequired);
RevertToSelf();
if (Result != ERROR_SUCCESS)
goto cleanupArgv;
@ -53,7 +149,9 @@ __declspec(dllexport) VOID __stdcall DeleteAdapter(HWND hwnd, HINSTANCE hinst, L
if (FAILED(CLSIDFromString(Argv[2], &Adapter.CfgInstanceID)))
goto cleanupArgv;
BOOL RebootRequired = FALSE;
ElevateToSystem();
WintunDeleteAdapter(&Adapter, &RebootRequired);
RevertToSelf();
cleanupArgv:
LocalFree(Argv);