/* Non-writable memory test case Copyright(c) 2015 Chris Eagle This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License version 2 as published by the Free Software Foundation. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ #include #include #include #include const uint8_t PROGRAM[] = "\xeb\x1a\x58\x83\xc0\x04\x83\xe0\xfc\x83\xc0\x01\xc7\x00\x78\x56" "\x34\x12\x83\xc0\x07\xc7\x00\x21\x43\x65\x87\x90\xe8\xe1\xff\xff" "\xff" "xxxxAAAAxxxBBBB"; // total size: 33 bytes /* jmp short bottom top: pop eax add eax, 4 and eax, 0xfffffffc add eax, 1 ; unaligned mov dword [eax], 0x12345678 ; try to write into code section add eax, 7 ; aligned mov dword [eax], 0x87654321 ; try to write into code section nop bottom: call top */ // callback for tracing instruction static void hook_code(ucengine *uc, uint64_t address, uint32_t size, void *user_data) { uint32_t esp; printf(">>> Tracing instruction at 0x%"PRIx64 ", instruction size = 0x%x\n", address, size); uc_reg_read(uc, UC_X86_REG_ESP, &esp); printf(">>> --- ESP is 0x%x\n", esp); } // callback for tracing memory access (READ or WRITE) static bool hook_mem_invalid(ucengine *uc, uc_mem_type type, uint64_t address, int size, int64_t value, void *user_data) { uint32_t esp; uc_reg_read(uc, UC_X86_REG_ESP, &esp); switch(type) { default: // return false to indicate we want to stop emulation return false; case UC_MEM_WRITE: //if this is a push, esp has not been adjusted yet if (esp == (address + size)) { uint32_t upper; upper = (esp + 0xfff) & ~0xfff; printf(">>> Stack appears to be missing at 0x%"PRIx64 ", allocating now\n", address); // map this memory in with 2MB in size uc_mem_map(uc, upper - 0x8000, 0x8000, UC_PROT_READ | UC_PROT_WRITE); // return true to indicate we want to continue return true; } printf(">>> Missing memory is being WRITTEN at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n", address, size, value); return false; case UC_MEM_WRITE_PROT: printf(">>> RO memory is being WRITTEN at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n", address, size, value); return false; } } #define STACK 0x500000 #define STACK_SIZE 0x5000 int main(int argc, char **argv, char **envp) { ucengine *uc; uchook trace1, trace2; uc_err err; uint8_t bytes[8]; uint32_t esp; int result; int map_stack = 0; if (argc == 2 && strcmp(argv[1], "--map-stack") == 0) { map_stack = 1; } printf("Memory mapping test\n"); // Initialize emulator in X86-32bit mode err = uc_open(UC_ARCH_X86, UC_MODE_32, &uc); if (err) { printf("Failed on uc_open() with error returned: %u\n", err); return 1; } uc_mem_map(uc, 0x100000, 0x1000, UC_PROT_ALL); uc_mem_map(uc, 0x200000, 0x2000, UC_PROT_ALL); uc_mem_map(uc, 0x300000, 0x3000, UC_PROT_ALL); uc_mem_map(uc, 0x400000, 0x4000, UC_PROT_READ); if (map_stack) { printf("Pre-mapping stack\n"); uc_mem_map(uc, STACK, STACK_SIZE, UC_PROT_READ | UC_PROT_WRITE); } else { printf("Mapping stack on first invalid memory access\n"); } esp = STACK + STACK_SIZE; uc_reg_write(uc, UC_X86_REG_ESP, &esp); // write machine code to be emulated to memory if (uc_mem_write(uc, 0x400000, PROGRAM, sizeof(PROGRAM))) { printf("Failed to write emulation code to memory, quit!\n"); return 2; } else { printf("Allowed to write to read only memory via uc_mem_write\n"); } //uc_hook_add(uc, &trace2, UC_HOOK_CODE, hook_code, NULL, (uint64_t)0x400000, (uint64_t)0x400fff); // intercept invalid memory events uc_hook_add(uc, &trace1, UC_HOOK_MEM_INVALID, hook_mem_invalid, NULL); // emulate machine code in infinite time printf("BEGIN execution - 1\n"); err = uc_emu_start(uc, 0x400000, 0x400000 + sizeof(PROGRAM), 0, 10); if (err) { printf("Expected failue on uc_emu_start() with error returned %u: %s\n", err, uc_strerror(err)); } else { printf("UNEXPECTED uc_emu_start returned UC_ERR_OK\n"); } printf("END execution - 1\n"); // emulate machine code in infinite time printf("BEGIN execution - 2\n"); //update eax to point to aligned memory (same as add eax,7 above) uint32_t eax = 0x40002C; uc_reg_write(uc, UC_X86_REG_EAX, &eax); //resume execution at the mov dword [eax], 0x87654321 //to test an aligned write as well err = uc_emu_start(uc, 0x400015, 0x400000 + sizeof(PROGRAM), 0, 2); if (err) { printf("Expected failure on uc_emu_start() with error returned %u: %s\n", err, uc_strerror(err)); } else { printf("UNEXPECTED uc_emu_start returned UC_ERR_OK\n"); } printf("END execution - 2\n"); printf("Verifying content at 0x400025 is unchanged\n"); if (!uc_mem_read(uc, 0x400025, bytes, 4)) { printf(">>> Read 4 bytes from [0x%x] = 0x%x\n", (uint32_t)0x400025, *(uint32_t*) bytes); if (0x41414141 != *(uint32_t*) bytes) { printf("ERROR content in read only memory changed\n"); } else { printf("SUCCESS content in read only memory unchanged\n"); } } else { printf(">>> Failed to read 4 bytes from [0x%x]\n", (uint32_t)(esp - 4)); return 4; } printf("Verifying content at 0x40002C is unchanged\n"); if (!uc_mem_read(uc, 0x40002C, bytes, 4)) { printf(">>> Read 4 bytes from [0x%x] = 0x%x\n", (uint32_t)0x40002C, *(uint32_t*) bytes); if (0x42424242 != *(uint32_t*) bytes) { printf("ERROR content in read only memory changed\n"); } else { printf("SUCCESS content in read only memory unchanged\n"); } } else { printf(">>> Failed to read 4 bytes from [0x%x]\n", (uint32_t)(esp - 4)); return 4; } printf("Verifying content at bottom of stack is readable and correct\n"); if (!uc_mem_read(uc, esp - 4, bytes, 4)) { printf(">>> Read 4 bytes from [0x%x] = 0x%x\n", (uint32_t)(esp - 4), *(uint32_t*) bytes); } else { printf(">>> Failed to read 4 bytes from [0x%x]\n", (uint32_t)(esp - 4)); return 4; } uc_close(uc); return 0; }