Created
October 2, 2016 16:55
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#include <stdio.h> | |
#include <assert.h> | |
#include <stdlib.h> | |
#include <capstone/capstone.h> | |
#include <unistd.h> | |
#include <sys/mman.h> | |
#include <fcntl.h> | |
#include <string.h> | |
#ifdef INFO | |
#define pr_info(...) \ | |
do {\ | |
fprintf(stderr, "[+]");\ | |
fprintf(stderr, __VA_ARGS__);\ | |
} while (0) | |
#else | |
#define pr_info(...) | |
#endif | |
#define pr_good_shit(...) \ | |
do {\ | |
fprintf(stderr, "[!]");\ | |
fprintf(stderr, __VA_ARGS__);\ | |
} while (0) | |
int main(int argc, char *argv[]) | |
{ | |
int fd = open("rev.bin", O_RDONLY); | |
assert(fd != -1); | |
unsigned char *memptr = mmap(NULL, 0x24c8d, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); | |
assert(memptr != MAP_FAILED); | |
unsigned char *mem = memptr; | |
#if 0 | |
for (size_t i = 0; i < 10; i++) | |
pr_info("%02x, ", mem[i]); | |
putchar('\n'); | |
getchar(); | |
#endif | |
char password[0x40] = { 0 }; | |
strcpy(password, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"); | |
csh handle; | |
cs_insn *insn; | |
size_t count; | |
if (cs_open(CS_ARCH_X86, CS_MODE_64, &handle) != CS_ERR_OK) | |
return -1; | |
count = cs_disasm(handle, mem, 0x100, 0x1000, 0, &insn); | |
if (!count) { | |
fprintf(stderr, "fuck :(\n"); | |
return -1; | |
} | |
for (size_t j = 0; j < count; ++j) { | |
const char *mn = insn[j].mnemonic; | |
const char *op = insn[j].op_str; | |
uint64_t a = insn[j].address; | |
pr_info("0x%llx:\t%s\t\t%s\n", a, mn, op); | |
if (!strcmp(mn, "mov") && !strcmp(op, "rax, rbx")) { | |
pr_info("Found move at offset %d\n", insn[j].address - 0x1000); | |
} else if (!strcmp(mn, "lea") && !strcmp(op, "rsi, qword ptr [rip + 0x34]")) { | |
uint64_t addr = a + 0x34 + 7; | |
pr_info("Decrypt from address: %p\n", (void *)addr); | |
uint64_t off = addr - 0x1000; | |
uint32_t *xor_ptr = (uint32_t *)(mem + off); | |
pr_info("xor_ptr: %p\n", xor_ptr); | |
uint32_t rcx = *xor_ptr; | |
++xor_ptr; | |
uint32_t eax = *xor_ptr; | |
++xor_ptr; | |
pr_info("rcx: 0x%x\n", rcx); | |
pr_info("eax: 0x%x\n", eax); | |
for (size_t i = 0; i < rcx; i ++) { | |
xor_ptr[i] ^= eax; | |
} | |
off += 8; | |
count = cs_disasm(handle, mem + off, 0x100, 0x1000, 0, &insn); | |
if (!count) { | |
fprintf(stderr, "fuck :(\n"); | |
return -1; | |
} | |
mem = mem + off; | |
off = 0; | |
j = 0; | |
continue; | |
} else if (!strcmp(mn, "mov") && strstr(op, "al, byte ptr [rax +")) { | |
pr_good_shit("0x%llx:\t%s\t\t%s\n", a, mn, op); | |
char *tmp = strchr(op, '+'); | |
++tmp; | |
//pr_good_shit("tmp: %s\n", tmp); | |
size_t pos = strtol(tmp, NULL, 16); | |
pr_good_shit("pos: 0x%lx\n", pos); | |
mn = insn[j + 1].mnemonic; | |
op = insn[j + 1].op_str; | |
a = insn[j + 1].address; | |
pr_good_shit("0x%llx:\t%s\t\t%s\n", a, mn, op); | |
tmp = strchr(op, ' '); | |
assert(tmp); | |
size_t val = strtol(tmp, NULL, 16); | |
pr_good_shit("and: 0x%lx\n", val); | |
mn = insn[j + 2].mnemonic; | |
op = insn[j + 2].op_str; | |
a = insn[j + 2].address; | |
pr_good_shit("0x%llx:\t%s\t\t%s\n", a, mn, op); | |
if (!strcmp(mn, "jne")) { | |
password[pos] &= ~val; | |
} else if (!strcmp(mn, "je")) { | |
password[pos] |= val; | |
} | |
} | |
} | |
cs_close(&handle); | |
pr_info("OK\n"); | |
close(fd); | |
pr_good_shit("password: %s\n", password); | |
return 0; | |
} |
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