其他
初试IDA&FRIDA联合调试简单ollvm保护的加密函数源码
本文为看雪论坛优秀文章
看雪论坛作者ID：无造
本文为看雪安卓高研3w班（5月班）优秀学员作品。
下面先让我们来看看讲师对学员学习成果的点评，以及学员的学习心得吧！
ollvm混淆强度不是很强的时候，可以通过IDA静态分析参数的交叉引用和返回值的来源，定位到与参数相关的函数，然后使用frida hook这些函数，定位到处理参数或生成返回结果的关键函数。
但是ollvm混淆强度比较强的时候，还是需要用到3月学习的trace方法来分析出参数被加密算法计算的过程。
yang老师本意应该是训练下trace的汇编代码阅读能力，但是由于ollvm混淆开得比较低，所以IDA的反汇编代码也是可以阅读，当时偷懒就没有专心去阅读trace了。
通过本题初次尝试了还原so文件代码，在没有开太多混淆的情况下还是可以使用IDA配合frida还原，像之前3月题目混淆开的高一点这种方式就要搞死掉了。
ps. 题目附件请点击“阅读原文”下载。
现在，看雪《安卓高级研修班（网课）》9月班开始招生啦！点击查看详情报名吧~
解题过程
#include <stdio.h> /* Swap bytes in 32 bit value. */#define __builtin_bswap32(x) \ ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >> 8) | \ (((x) & 0x0000ff00u) << 8) | (((x) & 0x000000ffu) << 24))#define bswap32(x) ((unsigned int)__builtin_bswap32(x)) void myenc(char* str) { /********** 程序写死 **********/ char* strWWW = "www.pediy.com&kanxue"; char* stryy = "yy"; unsigned char hexData[264] = { 0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76, 0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0, 0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15, 0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75, 0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84, 0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF, 0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8, 0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2, 0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73, 0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB, 0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79, 0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08, 0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A, 0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E, 0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF, 0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; /********** 计算长度 **********/ unsigned int lenStr = strlen(str); unsigned int lenPadding = (-(signed int)lenStr & 0xf); unsigned int lenEncStr = lenStr + 6 + lenPadding; unsigned char* bufEnc = (unsigned char*)malloc(lenEncStr); memset(bufEnc, 0, lenEncStr); /********** 开始填充 **********/ unsigned char* offBuf = (unsigned char*) (bufEnc + 6); //memmove(offBuf, strWWW, lenStrWWW); memmove(offBuf, str, lenStr); bufEnc[0] = stryy[0]; bufEnc[1] = stryy[1]; bufEnc[2] = 0x3; bufEnc[3] = lenPadding; //这里分2次设置 100 bufEnc[4] = 0x00; bufEnc[5] = 0x01; /********** 第一步加密 **********/ int i = 0; for (i = 6; i < lenEncStr; i++) { unsigned char tmpc = bufEnc[i]; unsigned char changec = hexData[tmpc]; bufEnc[i] = changec; } /********** 第二步加密 **********/ //生成第二步秘钥 unsigned int lenStrWWW = strlen(strWWW); //这里只复制0x10位 unsigned int lenBufKey = 0x10; unsigned char* bufKeyWWW = (unsigned char*)malloc(lenBufKey); memset(bufKeyWWW, 0, lenEncStr); memmove(bufKeyWWW, strWWW, lenBufKey); for (i = 0; i < lenBufKey; i++) { unsigned char tmpc = bufKeyWWW[i]; unsigned char changec = hexData[tmpc]; bufKeyWWW[i] = changec; } unsigned int* bufKeyWWWInt = (unsigned int*) bufKeyWWW; for (i = 0; i < 0x10 / 4; i++) { bufKeyWWWInt[i] = bswap32(bufKeyWWWInt[i]); } unsigned int* bufEncInt = (unsigned int*)offBuf; for (i = 0; i < (lenEncStr - 6) / 4; i++) { unsigned int part = bswap32(bufEncInt[i]); unsigned int partchange = part; if (i % 4 > 0) { partchange = (part >> 32 - i % 4 * 8) ^ (part << i % 4 * 8); } bufEncInt[i] = bswap32(partchange ^ bufKeyWWWInt[i%4]); } /********** 打印结果 **********/ for (i = 0; i < lenEncStr; i++) { if(bufEnc[i] < 0x10) printf("0", bufEnc[i]); printf("%x", bufEnc[i]); } printf("\nDone");} int main() { myenc("pediy_imyang_abcdefghij");} var addr_1500C = base_native.add(0x1500C); Interceptor.attach(addr_1500C, { onEnter: function (args) { this.args0 = args[0]; console.log("addr_1500C onEnter args0:",hexdump(this.args0)); var args1addr = ptr(args[1]).add(Process.pointerSize*2).readPointer(); console.log("addr_1500C onEnter args1:",args1addr.readCString()); }, onLeave: function (retval) { var resultaddr = ptr(this.args0).add(Process.pointerSize*5).readPointer(); console.log("addr_1500C onLeave args0:",hexdump(resultaddr)); } });看雪ID：无造
https://bbs.pediy.com/user-571058.htm
*本文由看雪论坛 无造 原创，转载请注明来自看雪社区。
推荐文章++++
好书推荐