前言

这次分享一个iOS端*车之家的登录接口的参数分析（仅供学习，严禁干坏事=。=）。本文为新手项，大佬请跳过。

准备

• iOS 12.5.5
• frida 14.0.0
• ipa 5rG96L2m5LmL5a62 11.33.5（爱思助手下载）

抓包

1. 抓包使用 charles，请自行安装并配置证书

2. 抓取登陆接口，点击账号登陆。使用假账密测试抓包 123456 / 123456，能够抓包成功

分析

1. 登录页面需要输入3个信息，分别是账号 / 密码 / 验证码，对应字段 logincode / userpwd / validcode

   • logincode为一个字符串，是输入账号加一个 %3 做前缀。

   • userpwd是一个加密字符串，需要待分析

   • validcode是验证码原文

2. 经过多次抓包分析，其他字段为一些设备信息，可以保持不变。_timestamp是一个10位的时间戳，_sign参数每次均改变，需要待分析

3. 分析前将包含 Mach-O文件的，后缀名为 .app的文件夹从爱思助手导出

   

4. 检查Mach-O文件是否需要脱壳

   • 找到Mach-O文件

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     file Payload/Autohome.app/* | grep Mach-O   Payload/Autohome.app/Autohome: Mach-O 64-bit executable arm64

   • 使用otool查看是否脱壳。1: 未脱壳；0: 脱壳；

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     % otool -l Payload/Autohome.app/Autohome | grep crypt     cryptoff 16384   cryptsize 28295168   cryptid 1

   • 使用 frida-ios-dump砸壳。

     • 需要app完全启动才能砸，如果砸壳中遇到阻塞请重试。

     • 砸完会生成一个 ipa，直接解压即可

   • 再次使用otool检测会发现 cryptid 1 变为 cryptid 0，即砸壳完成。

5. 开始分析userpwd参数。用ida将Mach-O文件 Autohome 打开，搜索字符串 userpwd

   

6. 点击第一个进入，tab键转换伪代码.

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   void __cdecl -[LOGThirdBindService bindThirdLogincode:userpwd:platformid:token:tokensecret:orginalname:openid:unionId:position:](LOGThirdBindService *self, SEL a2, id a3, id a4, int a5, id a6, id a7, id a8, id a9, id a10, int a11) {   id v11; // x23   id v12; // x22   id v13; // x21   int v14; // w27   id v15; // x20   LOGThirdBindService *v16; // x25   __int64 v17; // x1   void *v18; // x20   __int64 v19; // x1   __int64 v20; // x21   __int64 v21; // x1   __int64 v22; // x1   __int64 v23; // x1   __int64 v24; // x1   void *v25; // x0   int v26; // w19   NSMutableDictionary *v27; // x19   void *v28; // x0   __int64 v29; // x0   NSMutableDictionary *v30; // x19   void *v31; // x0   void *v32; // x0   NSMutableDictionary *v33; // x28   void *v34; // x0   NSMutableDictionary *v35; // x19   void *v36; // x0   NSMutableDictionary *v37; // x19   void *v38; // x0   NSMutableDictionary *v39; // x19   __int64 v40; // x0   __int64 v41; // x0   __int64 v42; // x27   void *v43; // [xsp+20h] [xbp-90h]   __int64 v44; // [xsp+50h] [xbp-60h]   char v45; // [xsp+58h] [xbp-58h]     v11 = a8;   v12 = a7;   v13 = a6;   v14 = a5;   v15 = a4;   v16 = self;   v43 = (void *)objc_retain(a3, a2);   v18 = (void *)objc_retain(v15, v17);   v20 = objc_retain(v13, v19);   objc_retain(v12, v21);   objc_retain(v11, v22);   objc_retain(a9, v23);   objc_retain(a10, v24);   sub_1016C6940((void *)v16->postDataDic);   v25 = sub_1016769C0(&OBJC_CLASS___AHUserSettings);   objc_retainAutoreleasedReturnValue(v25);   v26 = sub_1016978E0();   objc_release();   if ( v26 )   {     v27 = v16->postDataDic;     v28 = sub_1016769C0(&OBJC_CLASS___AHUserSettings);     objc_retainAutoreleasedReturnValue(v28);     v29 = sub_10167D700();     objc_retainAutoreleasedReturnValue(v29);     sub_1017025E0((void *)v27);     objc_release();     objc_release();   }   v30 = v16->postDataDic;   v31 = sub_101728CE0(v43);   objc_retainAutoreleasedReturnValue(v31);   sub_1017025E0((void *)v30);   objc_release();   v32 = -[LPNode count]_0(v18);   v33 = v16->postDataDic;   if ( v32 )   {     v34 = sub_10162E040(&OBJC_CLASS___AHMD5);     objc_retainAutoreleasedReturnValue(v34);     sub_1017025E0((void *)v33);     objc_release();   }   else   {     sub_1017025E0((void *)v16->postDataDic);   }   v35 = v16->postDataDic;   v36 = sub_1016AAC00(&OBJC_CLASS___NSNumber);   objc_retainAutoreleasedReturnValue(v36);   sub_1017025E0((void *)v35);   objc_release();   if ( !v20 )     objc_release();   sub_1017025E0((void *)v16->postDataDic);   sub_1017025E0((void *)v16->postDataDic);   sub_1017025E0((void *)v16->postDataDic);   sub_1017025E0((void *)v16->postDataDic);   if ( v14 == 26 )     sub_1017025E0((void *)v16->postDataDic);   v37 = v16->postDataDic;   v38 = sub_1016AAC00(&OBJC_CLASS___NSNumber);   objc_retainAutoreleasedReturnValue(v38);   sub_1017025E0((void *)v37);   objc_release();   sub_1017025E0((void *)v16->postDataDic);   v39 = v16->postDataDic;   v40 = sub_1016CB900(&OBJC_CLASS___AHAppSettings);   objc_retainAutoreleasedReturnValue(v40);   sub_1017025E0((void *)v39);   objc_release();   objc_initWeak(&v45, v16);   v41 = sub_10172F720(v16);   v42 = objc_retainAutoreleasedReturnValue(v41);   objc_copyWeak(&v44, &v45);   sub_10167B600(v42);   objc_release();   objc_destroyWeak(&v44);   objc_destroyWeak(&v45);   objc_release();   objc_release();   objc_release();   objc_release();   objc_release();   objc_release();   objc_release(); }

7. 分析发现有MD5字样，疑似为大写md5，用md5在线网站测试一下，果然是原滋原味的md5大写，未做任何魔改。那_sign字符串与userpwd的“样子”相似，可能也是md5。ios的md5使用的是 CC_MD5，那咱就直接用frida对CC_MD5进行hook了

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   // hook CC_MD5     let cc_md5 = Module.findExportByName(null, "CC_MD5");     console.log(`CC_MD5 addr>> ${cc_md5}`)     Interceptor.attach(cc_md5, {         onEnter: function(args){             // 获取传入 CC_MD5 函数的参数             const data = args[0];             const len = args[1];             const output = args[2];               console.log(`md5>> ${data.readCString()} | ${parseInt(len, 16)} |  ${output}`)             console.log("\nBacktrace:\n\t" + Thread.backtrace(this.context, Backtracer.ACCURATE).map(DebugSymbol.fromAddress).join('\n\t') + '\n');           }     })

8. hook CC_MD5后，分析打印日志, 在userpwd md5日志下发现一个可以日志。是一个312位字符串，放到在线网站中测试一下，加密后果然是_sign的值。

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   md5>> @7U$aPOE@$Version1_appidapp.iphone_timestamp1686474400autohomeuaiPhone    12.5.5    autohome    11.33.5    iPhonefPosition10004isCheckModeratorsRemote1isapp1logincode%3123456platform3reffersPosition1000405sessionid744ec98679b59e66a1fdc2deb77e7ee610812039showmob1userpwdE10ADC3949BA59ABBE56E057F20F883Evalidcodezbzt@7U$aPOE@$ | 312 |  0x16f6cd528   Backtrace:     0x1069566cc AHLoginServicesFramework!+[AHLoginServicesMD5 MD5WithString:]     0x1069515e4 AHLoginServicesFramework!__128-[AHLoginAccountLoginService accountLoginWidthUserName:PassWord:deviceToken:verifyCode:infoexpand:infoclub:sPosition:fPosition:]_block_invoke     0x1061ee424 AHBusinessFramework!-[AHServerTimeStampManager getServerTimeStampWithBlock:]     0x1069514a8 AHLoginServicesFramework!-[AHLoginAccountLoginService accountLoginWidthUserName:PassWord:deviceToken:verifyCode:infoexpand:infoclub:sPosition:fPosition:]     0x1069537b4 AHLoginServicesFramework!-[AHLoginAccountLoginManager loginWidthUserName:PassWord:deviceToken:verifyCode:infoexpand:infoclub:sPosition:fPosition:success:fail:]     0x100b13e9c Autohome!0x3e3e9c     0x1aebe9300 UIKitCore!-[UIApplication sendAction:to:from:forEvent:]     0x1ae692424 UIKitCore!-[UIControl sendAction:to:forEvent:]     0x101584aa4 Autohome!0xe54aa4     0x1ae692744 UIKitCore!-[UIControl _sendActionsForEvents:withEvent:]     0x1ae6917b0 UIKitCore!-[UIControl touchesEnded:withEvent:]     0x1aec205c4 UIKitCore!-[UIWindow _sendTouchesForEvent:]     0x1aec217ec UIKitCore!-[UIWindow sendEvent:]     0x1aec0185c UIKitCore!-[UIApplication sendEvent:]     0x1aecc79d4 UIKitCore!__dispatchPreprocessedEventFromEventQueue     0x1aecca100 UIKitCore!__handleEventQueueInternal

9. 再分析生成_sign的字符串，发现是由抓包中的各参数拼接成的，拼接代码如下。至此_sign参数分析结束。

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   import time import hashlib   """ @7U$aPOE@$Version1_appidapp.iphone_timestamp1686473693autohomeuaiPhone    12.5.5    autohome    11.33.5    iPhoneisCheckModeratorsRemote1isapp1logincode%3123456reffersessionid744ec98679b59e66a1fdc2deb77e7ee610812039showmob1userpwdE10ADC3949BA59ABBE56E057F20F883Evalidcodeiaeh@7U$aPOE@$ A40B768AA55F204329C7769C98BB1C69 """ usn = "123456" pwd = "123456"   en_md5 = lambda x: hashlib.md5(x.encode()).hexdigest()   def gen_sign(params):     s = f"@7U$aPOE@$Version{params['Version']}_appid{params['_appid']}_timestamp{params['_timestamp']}autohomeua{params['autohomeua']}isCheckModeratorsRemote{params['isCheckModeratorsRemote']}isapp{params['isapp']}logincode{params['logincode']}reffer{params['reffer']}sessionid{params['sessionid']}showmob{params['showmob']}userpwd{params['userpwd']}validcode{params['validcode']}@7U$aPOE@$"     return en_md5(s).upper()   if __name__ == "__main__":     params = {         "Version": 1,         "_appid": "app.iphone",         # "_timestamp": int(time.time()),         "_timestamp": "1686473693",         "autohomeua": "iPhone    12.5.5    autohome    11.33.5    iPhone",         "isCheckModeratorsRemote": 1,         "isapp": 1,         "logincode": f"%3{usn}",         "reffer": "",         "sessionid": "744ec98679b59e66a1fdc2deb77e7ee610812039",         "showmob": 1,         "userpwd": en_md5(pwd).upper(),         "validcode": "iaeh"     }     _sign = gen_sign(params)     print(f"{params=}\n{_sign=}")

小结

登录接口的 userpwd 和 _sign 已经分析完了。比较简单，就一个大写md5，还没有任何魔改，熟悉算法的佬应该很快就反应过来的。可惜俺不是

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