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[分享]UVMSE-吊打苹果iOS加密代码，依此类推～
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发表于: 2021-8-3 12:25
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苹果从iOS10开始，就对自己的核心逻辑做了很强的加密，典型的就是字符串加密、间接跳转br、间接调用blr，静态分析和动态调试都十分低效。现在，通过UVMSE，我们可以分分钟解密它的加密代码，上结果：
1 | https://gitee.com/geekneo/reverseapplecode/tree/master/bin |
这个采样数据库是针对itunesstored kbsyn算法的一个子函数采样数据，该函数在计算kbsyn时会调用，属于加密代码，IDA的初始流程图如下：
F5反编译：
1 2 3 4 | void __fastcall sub_100274B50(__int64 a1, __int64 a2, __int64 a3, __int64 a4, __int64 a5, __int64 a6){ JUMPOUT(__CS__, (char *)&loc_100274B98 + dword_1002CA440[(a5 == 0 || a6 == 0) + 3]);} |
可以看到，因为br这个间接调用，IDA是没办法把这个函数完整识别出来的。所以，我们需要使用UVMSE实现一次采样，如下：
然后就可以看到该函数的执行流CFG，还好，并不是很复杂：
再看看简化还原后的采样CFG，进一步减少了基本块：
然后，我们导出重写后的函数扔进IDA里面看看效果，此时IDA已经可以正常分析该函数了：
F5反编译：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 | __int64 __fastcall sub_100274B50(int a1, __int64 a2, int a3, int a4, unsigned __int64 *a5, int *a6){ BOOL v6; // w8 char *v7; // x10 int *v8; // x19 unsigned __int64 *v9; // x23 int v10; // w22 __int64 v11; // x20 int v12; // w24 int v13; // w28 int v14; // w10 char *v15; // x10 int v16; // w28 int v17; // w10 char *v18; // x10 int v19; // w28 __int64 v20; // x23 int v21; // w8 int v22; // w24 __int64 v23; // x8 int v24; // w10 int v25; // w21 char *v26; // x8 char *v27; // x22 int v28; // w9 char *v29; // x8 int v30; // w11 int v31; // w21 char *v32; // x8 char *v33; // x8 int v34; // w23 int v35; // w8 char *v36; // x8 int v37; // w8 int v38; // w9 char *v39; // x9 int v40; // w27 BOOL v41; // w9 int v42; // w10 int v43; // w23 char *v44; // x8 int v45; // w21 unsigned __int64 v46; // x0 int v47; // w10 int v48; // w23 char *v49; // x8 int v50; // w9 int v51; // w14 unsigned int v52; // w15 int v53; // w13 int v54; // w9 int v55; // w12 int v56; // w10 char *v57; // x10 unsigned __int64 v58; // x10 unsigned int v59; // w13 int v60; // w16 char *v61; // x1 __int64 v62; // x14 BOOL v63; // w15 int v64; // w12 int v65; // t1 unsigned int v66; // w15 signed int v67; // w16 int8x16_t v68; // q0 int v69; // w1 unsigned __int64 v70; // x3 unsigned __int64 v71; // x2 int8x16_t v72; // q2 char *v73; // x1 int v74; // w9 bool v75; // zf BOOL v76; // w13 signed int v77; // w14 int v78; // w13 int v79; // w14 int v80; // w12 __int64 v81; // x13 int v82; // w13 __int64 v83; // x14 char *v84; // x13 int v85; // w21 __int64 v86; // x1 unsigned __int64 *v88; // [xsp+0h] [xbp-C0h] int v89; // [xsp+10h] [xbp-B0h] __int64 v90; // [xsp+10h] [xbp-B0h] int *v91; // [xsp+18h] [xbp-A8h] int v92; // [xsp+24h] [xbp-9Ch] __int64 *v93; // [xsp+28h] [xbp-98h] int v94; // [xsp+34h] [xbp-8Ch] unsigned __int64 v95; // [xsp+38h] [xbp-88h] unsigned __int64 *v96; // [xsp+40h] [xbp-80h] __int64 *v97; // [xsp+48h] [xbp-78h] int *v98; // [xsp+50h] [xbp-70h] int v99; // [xsp+58h] [xbp-68h] int v100; // [xsp+5Ch] [xbp-64h] v89 = a4; v6 = a5 == 0LL || a6 == 0LL; v7 = (char *)&loc_100274B98 + dword_1002CA440[v6 + 3]; v8 = a6; v9 = a5; v10 = a3; v11 = a2; v12 = a1; v13 = 250416724 * v6 + 4 * !v6 + 3; *a5 = 0LL; *a6 = 0; HIDWORD(v96) = v13 + 318538391 * ((unsigned __int64)&v96 ^ 0xA472A4EA) + 1085017171; sub_100275504(&v96); if ( (_DWORD)v96 == 818020368 ) v14 = v13 + 1; else v14 = v13; v15 = (char *)&loc_100274BC4 + dword_1002CA440[v14]; v16 = v13 + 250416720 * ((_DWORD)v96 != 818020368) - 7 * ((_DWORD)v96 == 818020368); HIDWORD(v96) = v16 + 344300003 * ((unsigned __int64)&v96 ^ 0x1BB52AD3); v97 = (__int64 *)&v91; sub_10028C214(&v96); if ( (_DWORD)v96 == 818020368 ) v17 = v16 + 1; else v17 = v16; v18 = (char *)&loc_100274C60 + dword_1002CA440[v17]; v88 = v9; v19 = v16 + 250416727 * ((_DWORD)v96 != 818020368) + (((_DWORD)v96 == 818020368) | 8 * ((_DWORD)v96 == 818020368)); v20 = (__int64)v91; v21 = 1089068225 * v12 + 1917068697; v22 = 629865641 * ((unsigned __int64)&v96 ^ 0xB415044F); HIDWORD(v96) = v22 ^ v21; LODWORD(v97) = (v19 - 6) ^ v22; v98 = v91; v23 = (__int64)*(&off_10036E8E0 + v19 + 208); sub_10026BF54(&v96); HIDWORD(v96) = v22 ^ (1089068225 * HIDWORD(v11) + 1917068697); LODWORD(v97) = (v19 - 6) ^ v22; v98 = (int *)v20; sub_10026BF54(&v96); HIDWORD(v96) = v22 ^ (1089068225 * v11 + 1917068697); LODWORD(v97) = (v19 - 6) ^ v22; v98 = (int *)v20; sub_10026BF54(&v96); v98 = (int *)v20; HIDWORD(v96) = v22 ^ (1089068225 * v10 + 1917068697); LODWORD(v97) = (v19 - 6) ^ v22; sub_10026BF54(&v96); v98 = (int *)v20; HIDWORD(v96) = v22 ^ (1089068225 * v89 + 1917068697); LODWORD(v97) = (v19 - 6) ^ v22; sub_10026BF54(&v96); if ( (_DWORD)v96 == 818020368 ) v24 = v19 + 1; else v24 = v19; v25 = -7 * ((_DWORD)v96 != 818020368) + v19 - 4 * ((_DWORD)v96 == 818020368); v26 = (char *)&loc_100274CD0 + dword_1002CA440[v24]; v27 = (char *)*(&off_10036E8E0 + v19 + 155) - 6; v28 = 1870922891 * ((unsigned __int64)&v96 ^ 0x40116C51); HIDWORD(v96) = v28 ^ 0xE15FB441; v99 = v28 + 1526806456; v100 = (v25 - 4) ^ v28; v97 = (__int64 *)&v93; v98 = (int *)v20; v29 = (char *)*(&off_10036E8E0 + v25 + 199) - 14; sub_10027A810(&v96); if ( (_DWORD)v96 == 818020368 ) v30 = v25 + 1; else v30 = v25; v31 = -3 * ((_DWORD)v96 != 818020368) + v25 + 6 * ((_DWORD)v96 == 818020368); v32 = (char *)&loc_100274E1C + dword_1002CA440[v30]; v90 = v20; v98 = &v92; *(_QWORD *)&v99 = v93; LODWORD(v97) = v31 + 357855347 * ((unsigned __int64)&v96 ^ 0x17939E0) + 1288018446; v96 = &v95; sub_10028D8CC(&v96); HIDWORD(v98) = (v31 - 5) ^ 629865641 * ((unsigned __int64)&v96 ^ 0xB415044F); v96 = (unsigned __int64 *)&v94; v97 = v93; v33 = (char *)*(&off_10036E8E0 + v31 + 66) - 11; sub_100299998(&v96); LODWORD(v96) = v31 - 1785876119 * ((unsigned __int64)&v96 ^ 0x378C1BBF) - 6; v97 = v93; sub_10029F838(&v96); v34 = v31 + 4 * ((_DWORD)v98 != 818020368) + 2 * ((_DWORD)v98 == 818020368); if ( (_DWORD)v98 == 818020368 ) v35 = v31 + 1; else v35 = v31; v36 = (char *)&loc_100274EBC + dword_1002CA440[v35]; v37 = v34 + 2 * (v94 != 0) + ((v94 == 0) | 2 * (v94 == 0)); if ( v94 ) v38 = v31 + 4 * ((_DWORD)v98 != 818020368) + 2 * ((_DWORD)v98 == 818020368); else v38 = v34 + 1; v39 = (char *)&loc_100274FBC + dword_1002CA440[v38]; v40 = v92; v41 = v92 == 862660833; v42 = v37 + 4 * (v92 != 862660833); if ( v92 == 862660833 ) ++v37; v43 = v42 - v41; v44 = (char *)&loc_10027501C + dword_1002CA440[v37]; v45 = v92 - 862660833; v46 = ((__int64 (__fastcall *)(_QWORD))((char *)*(&off_10036E8E0 + v42 - v41 + 204) - 2))((unsigned int)(v92 - 862660833)); if ( v46 ) v47 = v43; else v47 = v43 + 1; v48 = v43 - 2 * (v46 != 0) - ((v46 == 0) | 4 * (v46 == 0)); v49 = (char *)&loc_10027505C + dword_1002CA440[v47]; v50 = v40 - ((2 * v40 + 422161982) & 0x47D9921C) + 1887543341; v51 = v50 ^ 0x4D326F6D; v52 = 2 * v50 & 0xDDBD4CC6 ^ 0x45990004; v53 = v52 + (v50 ^ 0x4D326F6D); v54 = v53 + 402651648; v55 = (((v53 != -287398301) | (unsigned __int16)(4 * (v53 != -287398301))) & 0xFFEF | 16 * (v53 == -287398301)) + v48; if ( v53 == -287398301 ) v56 = v48 + 1; else v56 = v48; v57 = (char *)&loc_1002750B4 + dword_1002CA440[v56]; v58 = v95; v59 = v53 + 287398301; v60 = ((v59 > 0x1F) | 4 * (v59 > 0x1F)) + 250416704 * (v59 < 0x20) + v55; if ( v59 < 0x20 ) ++v55; v61 = (char *)&loc_100275154 + dword_1002CA440[v55]; v62 = v52 + v51 + 287398300; v63 = v95 < v46 + v62 + 1 && v46 < v95 + v62 + 1; v64 = v60 + 250416699 * (v63 + !v63); v65 = dword_1002CA440[v60 + v63]; v66 = v59 & 0xFFFFFFE0; v67 = (v59 & 0xFFFFFFE0) - 32; v68.n128_u64[0] = 8246779703540740722LL; v68.n128_u64[1] = 8246779703540740722LL; while ( 1 ) { v69 = v64 - 250416701; if ( !v67 ) v69 = v64 - 250416700; v70 = v58 + (unsigned int)v62; v71 = v46 + (unsigned int)v62; v72 = veorq_s8(*(int8x16_t *)(v70 - 31), v68); *(int8x16_t *)(v71 - 15) = veorq_s8(*(int8x16_t *)(v70 - 15), v68); *(int8x16_t *)(v71 - 31) = v72; v64 -= 250416701 * (v67 == 0); v73 = (char *)&loc_100275210 + dword_1002CA440[v69 + 4]; if ( v67 >= 0 ) break; LODWORD(v62) = v62 - 32; v67 -= 32; } v74 = v54 - v66; v75 = v59 == v66; v76 = v59 == v66; v77 = !v75; v78 = 250416701 * v77 + 8 * v76; if ( v75 ) v79 = v64 + 1; else v79 = v64; v80 = v78 + v64; v81 = dword_1002CA440[v79]; do { v82 = v80 - 250416701; v83 = (unsigned int)(v74-- - 115253348); if ( v74 == 115253347 ) v82 = v80 - 250416700; *(_BYTE *)(v46 + v83) = *(_BYTE *)(v58 + v83) ^ 0x72; v80 -= 250416693 * (v74 == 115253347); v84 = (char *)&loc_100275298 + dword_1002CA440[v82 + 6]; } while ( v74 < 115253347 ); *v88 = v46; *v8 = v45; v85 = v80 - 32; v97 = v93; LODWORD(v96) = v80 - 32 - 1277345827 * ((unsigned __int64)&v96 ^ 0xE4E0F794); sub_1002A79C0(&v96, v73); LODWORD(v96) = v85 - 1277345827 * ((unsigned __int64)&v96 ^ 0xE4E0F794); v97 = (__int64 *)v90; sub_1002A79C0(&v96, v86); return 0LL;} |
可以看到，重写后的br、blr均修复为b、bl等正常的函数调用，进一步就可以递归分析整个算法的来龙去脉。
UVMSE用户手册可以在这里下载：
1 | https://gitee.com/yunyoo/vsusermanual |
Have fun～
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