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syscall

• Recho

  CTF/XCTF 2021. 2. 11. 04:21

  Disassembly 디스어셈블리 undefined8 main(void) { int64_t iVar1; char *str; // rbp-0x40 char *buf; // rbp-0x30 undefined8 size; Init(); write(1, "Welcome to Recho server!\n", 0x19); while( true ) { iVar1 = read(0, str, 0x10); if (iVar1 < 1) break; size = atoi(str); if (size < 0x10) { size = 0x10; } len = read(0, buf, size); buf[len] = 0; printf("%s", buf); } return 0; } read를 통해 buf에 입력받을 때 스택 버퍼 오버플로우..

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• Register

  CTF/HackCTF 2021. 2. 4. 23:49

  Disassembly 디스어셈블리 undefined8 main(void) { alarm(5); setvbuf(_reloc.stdout, 0, 2, 0); build(); return 0; } main은 build를 호출한다. void build(void) { int32_t iVar1; int64_t in_FS_OFFSET; int64_t var_40h; int64_t var_38h; int64_t var_30h; int64_t var_28h; int64_t var_20h; int64_t var_18h; int64_t var_10h; int64_t var_8h; var_8h = *(int64_t *)(in_FS_OFFSET + 0x28); signal(0xe, handler); do { do { get_o..

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