bugku-reverse-入门逆向 Easy_vb re 游戏过关逆向入门

news2024/11/18 6:29:01

入门逆向

下载文件解压后拖入IDA中

Easy_vb

同样方法解压后拖入IDA

Easy_re

下载解压后打开

似乎有点逗

查下壳先

拖入IDA

选中这两行字符转译

单击a

得到flag

游戏过关

下载文件解压

打开发现要把8个都点亮每次输入会把输入的数本身和他上一个下一个都改变状态，当所有都变亮，则出现flag

比如输入1后和输入2后的对比大于8就会报错

使用IDA打开

ALT+T查找flag

双击查看字符串内存地址变量位于只读数据区(rdata)

查看伪代码

int sub_45E940()
{
  signed int i; // [esp+D0h] [ebp-94h]
  char v2; // [esp+DCh] [ebp-88h]
  char v3; // [esp+DDh] [ebp-87h]
  char v4; // [esp+DEh] [ebp-86h]
  char v5; // [esp+DFh] [ebp-85h]
  char v6; // [esp+E0h] [ebp-84h]
  char v7; // [esp+E1h] [ebp-83h]
  char v8; // [esp+E2h] [ebp-82h]
  char v9; // [esp+E3h] [ebp-81h]
  char v10; // [esp+E4h] [ebp-80h]
  char v11; // [esp+E5h] [ebp-7Fh]
  char v12; // [esp+E6h] [ebp-7Eh]
  char v13; // [esp+E7h] [ebp-7Dh]
  char v14; // [esp+E8h] [ebp-7Ch]
  char v15; // [esp+E9h] [ebp-7Bh]
  char v16; // [esp+EAh] [ebp-7Ah]
  char v17; // [esp+EBh] [ebp-79h]
  char v18; // [esp+ECh] [ebp-78h]
  char v19; // [esp+EDh] [ebp-77h]
  char v20; // [esp+EEh] [ebp-76h]
  char v21; // [esp+EFh] [ebp-75h]
  char v22; // [esp+F0h] [ebp-74h]
  char v23; // [esp+F1h] [ebp-73h]
  char v24; // [esp+F2h] [ebp-72h]
  char v25; // [esp+F3h] [ebp-71h]
  char v26; // [esp+F4h] [ebp-70h]
  char v27; // [esp+F5h] [ebp-6Fh]
  char v28; // [esp+F6h] [ebp-6Eh]
  char v29; // [esp+F7h] [ebp-6Dh]
  char v30; // [esp+F8h] [ebp-6Ch]
  char v31; // [esp+F9h] [ebp-6Bh]
  char v32; // [esp+FAh] [ebp-6Ah]
  char v33; // [esp+FBh] [ebp-69h]
  char v34; // [esp+FCh] [ebp-68h]
  char v35; // [esp+FDh] [ebp-67h]
  char v36; // [esp+FEh] [ebp-66h]
  char v37; // [esp+FFh] [ebp-65h]
  char v38; // [esp+100h] [ebp-64h]
  char v39; // [esp+101h] [ebp-63h]
  char v40; // [esp+102h] [ebp-62h]
  char v41; // [esp+103h] [ebp-61h]
  char v42; // [esp+104h] [ebp-60h]
  char v43; // [esp+105h] [ebp-5Fh]
  char v44; // [esp+106h] [ebp-5Eh]
  char v45; // [esp+107h] [ebp-5Dh]
  char v46; // [esp+108h] [ebp-5Ch]
  char v47; // [esp+109h] [ebp-5Bh]
  char v48; // [esp+10Ah] [ebp-5Ah]
  char v49; // [esp+10Bh] [ebp-59h]
  char v50; // [esp+10Ch] [ebp-58h]
  char v51; // [esp+10Dh] [ebp-57h]
  char v52; // [esp+10Eh] [ebp-56h]
  char v53; // [esp+10Fh] [ebp-55h]
  char v54; // [esp+110h] [ebp-54h]
  char v55; // [esp+111h] [ebp-53h]
  char v56; // [esp+112h] [ebp-52h]
  char v57; // [esp+113h] [ebp-51h]
  char v58; // [esp+114h] [ebp-50h]
  char v59; // [esp+120h] [ebp-44h]
  char v60; // [esp+121h] [ebp-43h]
  char v61; // [esp+122h] [ebp-42h]
  char v62; // [esp+123h] [ebp-41h]
  char v63; // [esp+124h] [ebp-40h]
  char v64; // [esp+125h] [ebp-3Fh]
  char v65; // [esp+126h] [ebp-3Eh]
  char v66; // [esp+127h] [ebp-3Dh]
  char v67; // [esp+128h] [ebp-3Ch]
  char v68; // [esp+129h] [ebp-3Bh]
  char v69; // [esp+12Ah] [ebp-3Ah]
  char v70; // [esp+12Bh] [ebp-39h]
  char v71; // [esp+12Ch] [ebp-38h]
  char v72; // [esp+12Dh] [ebp-37h]
  char v73; // [esp+12Eh] [ebp-36h]
  char v74; // [esp+12Fh] [ebp-35h]
  char v75; // [esp+130h] [ebp-34h]
  char v76; // [esp+131h] [ebp-33h]
  char v77; // [esp+132h] [ebp-32h]
  char v78; // [esp+133h] [ebp-31h]
  char v79; // [esp+134h] [ebp-30h]
  char v80; // [esp+135h] [ebp-2Fh]
  char v81; // [esp+136h] [ebp-2Eh]
  char v82; // [esp+137h] [ebp-2Dh]
  char v83; // [esp+138h] [ebp-2Ch]
  char v84; // [esp+139h] [ebp-2Bh]
  char v85; // [esp+13Ah] [ebp-2Ah]
  char v86; // [esp+13Bh] [ebp-29h]
  char v87; // [esp+13Ch] [ebp-28h]
  char v88; // [esp+13Dh] [ebp-27h]
  char v89; // [esp+13Eh] [ebp-26h]
  char v90; // [esp+13Fh] [ebp-25h]
  char v91; // [esp+140h] [ebp-24h]
  char v92; // [esp+141h] [ebp-23h]
  char v93; // [esp+142h] [ebp-22h]
  char v94; // [esp+143h] [ebp-21h]
  char v95; // [esp+144h] [ebp-20h]
  char v96; // [esp+145h] [ebp-1Fh]
  char v97; // [esp+146h] [ebp-1Eh]
  char v98; // [esp+147h] [ebp-1Dh]
  char v99; // [esp+148h] [ebp-1Ch]
  char v100; // [esp+149h] [ebp-1Bh]
  char v101; // [esp+14Ah] [ebp-1Ah]
  char v102; // [esp+14Bh] [ebp-19h]
  char v103; // [esp+14Ch] [ebp-18h]
  char v104; // [esp+14Dh] [ebp-17h]
  char v105; // [esp+14Eh] [ebp-16h]
  char v106; // [esp+14Fh] [ebp-15h]
  char v107; // [esp+150h] [ebp-14h]
  char v108; // [esp+151h] [ebp-13h]
  char v109; // [esp+152h] [ebp-12h]
  char v110; // [esp+153h] [ebp-11h]
  char v111; // [esp+154h] [ebp-10h]
  char v112; // [esp+155h] [ebp-Fh]
  char v113; // [esp+156h] [ebp-Eh]
  char v114; // [esp+157h] [ebp-Dh]
  char v115; // [esp+158h] [ebp-Ch]

  sub_45A7BE("done!!! the flag is ");
  v59 = 18;
  v60 = 64;
  v61 = 98;
  v62 = 5;
  v63 = 2;
  v64 = 4;
  v65 = 6;
  v66 = 3;
  v67 = 6;
  v68 = 48;
  v69 = 49;
  v70 = 65;
  v71 = 32;
  v72 = 12;
  v73 = 48;
  v74 = 65;
  v75 = 31;
  v76 = 78;
  v77 = 62;
  v78 = 32;
  v79 = 49;
  v80 = 32;
  v81 = 1;
  v82 = 57;
  v83 = 96;
  v84 = 3;
  v85 = 21;
  v86 = 9;
  v87 = 4;
  v88 = 62;
  v89 = 3;
  v90 = 5;
  v91 = 4;
  v92 = 1;
  v93 = 2;
  v94 = 3;
  v95 = 44;
  v96 = 65;
  v97 = 78;
  v98 = 32;
  v99 = 16;
  v100 = 97;
  v101 = 54;
  v102 = 16;
  v103 = 44;
  v104 = 52;
  v105 = 32;
  v106 = 64;
  v107 = 89;
  v108 = 45;
  v109 = 32;
  v110 = 65;
  v111 = 15;
  v112 = 34;
  v113 = 18;
  v114 = 16;
  v115 = 0;
  v2 = 123;
  v3 = 32;
  v4 = 18;
  v5 = 98;
  v6 = 119;
  v7 = 108;
  v8 = 65;
  v9 = 41;
  v10 = 124;
  v11 = 80;
  v12 = 125;
  v13 = 38;
  v14 = 124;
  v15 = 111;
  v16 = 74;
  v17 = 49;
  v18 = 83;
  v19 = 108;
  v20 = 94;
  v21 = 108;
  v22 = 84;
  v23 = 6;
  v24 = 96;
  v25 = 83;
  v26 = 44;
  v27 = 121;
  v28 = 104;
  v29 = 110;
  v30 = 32;
  v31 = 95;
  v32 = 117;
  v33 = 101;
  v34 = 99;
  v35 = 123;
  v36 = 127;
  v37 = 119;
  v38 = 96;
  v39 = 48;
  v40 = 107;
  v41 = 71;
  v42 = 92;
  v43 = 29;
  v44 = 81;
  v45 = 107;
  v46 = 90;
  v47 = 85;
  v48 = 64;
  v49 = 12;
  v50 = 43;
  v51 = 76;
  v52 = 86;
  v53 = 13;
  v54 = 114;
  v55 = 1;
  v56 = 117;
  v57 = 126;
  v58 = 0;
  for ( i = 0; i < 56; ++i )                    // flag逻辑
  {
    *(&v2 + i) ^= *(&v59 + i);
    *(&v2 + i) ^= 0x13u;
  }
  return sub_45A7BE("%s\n");
}

flag生成逻辑将v2 ~ v58各字符分别与v59 ~ v115进行异或再与0x13u(十进制19)进行异或所得的v2~58字符即为flag

由此编写python脚本：

a = [18,64,98,5,2,4,6,3,6,48,49,65,32,12,48,65,31,78,62,32,49,32,
    1,57,96,3,21,9,4,62,3,5,4,1,2,3,44,65,78,32,16,97,54,16,44,
    52,32,64,89,45,32,65,15,34,18,16,0]
b = [123,32,18,98,119,108,65,41,124,80,125,38,124,111,74,49,
    83,108,94,108,84,6,96,83,44,121,104,110,32,95,117,101,99,
    123,127,119,96,48,107,71,92,29,81,107,90,85,64,12,43,76,86,
    13,114,1,117,126,0]
flag = ''
for i in range(56):
    b[i] ^= a[i]
    b[i] ^= 19
    flag += chr(b[i])
    
print(flag)

得到flag