【iOS 逆向】某营业厅算法分析
作者：小陈
- 2022 年 9 月 05 日 四川
本文字数：8468 字
阅读完需：约 28 分钟
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1.目标
使用 frida stalker 分析某营业厅的签名算法。
2.操作环境
mac 系统
frida-ios-dump：砸壳
Charles：抓包
已越狱 iOS 设备：脱壳及 frida 调试
IDA Pro：静态分析
3.流程
寻找切入点
在账号密码登录页，点击登录，通过 Charles 抓包获取到关键词为 loginAuthCipherAsymmertric，这也就是我们的切入点：
分析过程
使用 frida-ios-dump 的砸壳命令dump.py com.wemomo.momoappdemo1 砸壳获取到 ipa 文件，再使用 IDA Pro 编译 ipa 文件，然后搜索搜索字符串 loginAuthCipherAsymmertric 失败，继续搜索 userLoginNormal，失败。该应用对字符串都进行了混淆。搜索无果后，只能换个思路，尝试 hook NSMutableURLRequest 类。
使用 frida-trace 的frida-trace -UF -m "-[NSMutableURLRequest setHTTPBody:]"命令跟踪该函数，js 代码如下:
{ onEnter(log, args, state) { var arg2 = new ObjC.Object(args[2]) log(`-[NSMutableURLRequest setHTTPBody:${arg2.bytes().readUtf8String()}]`); }, onLeave(log, retval, state) { }}
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点击登录后，获取到的日志如下：
-[NSMutableURLRequest setHTTPBody:ndh=1&t=00%2F00%2F0000%2000%3A00%3A00%200%20-480&c.&v3=baoguang_event&deviceId=7B063D78-C5D8-45A6-8E3D-37B787DEB2CD&hitDate=2022-09-02%2023%3A01%3A52¤tPage=Denglujh-kuandaidenglushouji&v63=101-106&appVersion=4&c25=%E6%B6%88%E6%81%AF%2BSyjh-sytop-message-1_1%2B%28null%29%2B%28null%29&es_timestamp=1662130874519&v60=lo158b3b81&codeVersion=22033101&v65=WIFI&v61=disable&a.&action=trkAppBgAction&OSVersion=iOS%2012.5.5&DeviceName=iPhone7%2C2&RunMode=Application&AppID=CTPocket%209.4.0%20%284%29&CarrierName=%28null%29&Resolution=750x1334&TimeSinceLaunch=2536&.a&lunchtype=aut_lunch&.c&pev2=AMACTION%3AtrkAppBgAction&pageName=CTPocket%2F4&ce=UTF-8&aid=540B88F2280D4599-146C532D0B076319&pe=lnk_o&cp=foreground]-[NSMutableURLRequest setHTTPBody:{"content":{"fieldData":{"isChinatelecom":"0","phoneNum":"13245678901","authentication":"222222","accountType":"","deviceUid":"ddecc53e1fce414e9e89b6ea47e567e3","systemVersion":"12.5.5","loginAuthCipherAsymmertric":"o4Af5TvC5iV25FhTE9NIZJEiqHLWg+JkcCF4AGp727uhvFydBWvkCz8HauqTDpIoRhpfqLUMLN6Hk1ucBZOPYhCHwm4N\/4PuPsMWZTEbips+uL74ufgeLMci0nIZRmFsCsBrgvUVkebKcRo2yO0DZQ2jtnKe+cG78v6aOHl5ssk=","loginType":"4"},"attach":"iPhone"},"headerInfos":{"broadAccount":"","source":"120002","shopId":"20004","userLoginName":"13245678901","broadToken":"","code":"userLoginNormal","clientType":"#9.4.0#channel50#iPhone 6#","token":"","timestamp":"20220902230115","sourcePassword":"TiqmIZ"}}]-[NSMutableURLRequest setHTTPBody:ndh=1&t=00%2F00%2F0000%2000%3A00%3A00%200%20-480&c.&v3=hit_event&deviceId=7B063D78-C5D8-45A6-8E3D-37B787DEB2CD&hitDate=2022-09-02%2023%3A01%3A05&c20=%E5%8F%B3%E6%BB%91%E7%99%BB%E5%BD%95&appVersion=4&lastAction=Denglujh-denglu-mima-2_8%5E%E5%8F%B3%E6%BB%91%E7%99%BB%E5%BD%95&method=trkAppButtonClick%20-action%20...&v63=101-106¤tPage=Denglujh-kuandaidenglushouji&es_timestamp=1662130875056&c21=Denglujh-denglu-mima-2_8&v60=lo158b3b81&codeVersion=22033101&v65=WIFI&v61=disable&a.&action=trkAppButtonClick&OSVersion=iOS%2012.5.5&CarrierName=%28null%29&DeviceName=iPhone7%2C2&AppID=CTPocket%209.4.0%20%284%29&RunMode=Application&Resolution=750x1334&TimeSinceLaunch=2537&.a&lunchtype=aut_lunch&prePageAction=hit_event&.c&pev2=AMACTION%3AtrkAppButtonClick&pageName=CTPocket%2F4&ce=UTF-8&aid=540B88F2280D4599-146C532D0B076319&pe=lnk_o&cp=foreground]
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搜索登录的账号 13245678901 后，发现日志里有登录的 body 信息，在 setHTTPBody 的 js 代码里打印堆栈：
{ onEnter(log, args, state) { var arg2 = new ObjC.Object(args[2]) log(`-[NSMutableURLRequest setHTTPBody:${arg2.bytes().readUtf8String()}]`); log('NSMutableURLRequest setHTTPBody called from:\n' + Thread.backtrace(this.context, Backtracer.ACCURATE) .map(DebugSymbol.fromAddress).join('\n') + '\n'); }, onLeave(log, retval, state) { }}
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获取到的堆栈信息如下：
0x10397f4d8 CTPocket!-[AFJSONRequestSerializer requestBySerializingRequest:withParameters:error:]0x10397ae50 CTPocket!-[AFHTTPRequestSerializer requestWithMethod:URLString:parameters:error:]0x10394edac CTPocket!-[AFHTTPSessionManager dataTaskWithHTTPMethod:URLString:parameters:headers:uploadProgress:downloadProgress:success:failure:]0x10394e378 CTPocket!-[AFHTTPSessionManager POST:parameters:headers:progress:success:failure:]0x101b8fae8 CTPocket!-[ESHttpSessionManager postWithHost:urlString:parameters:success:failure:]0x1015f91c8 CTPocket!-[ESNetworkingManager postWithURLString:parameters:modifiParamsBlock:success:failure:]0x100c14da4 CTPocket!-[ESLoginService loginWithPhoneNbr:type:code:isChinatelecom:slidingTime:percentage:success:failure:]0x101f85f58 CTPocket!-[ESBindLoginViewController phoneLoginWithPhoneNbr:type:code:slidingTime:percentage:isChinatelecom:isBind:failureBlock:]0x101f6a060 CTPocket!-[ESBindLoginViewController phoneLoginViewController:inputView:didSliderWithSlidingTime:Percentage:phoneNbr:passwd:loginType:isChinatelecom:isBind:failureBlock:]0x102ccb964 CTPocket!-[ESLoginViewController phoneLoginView:inputView:didSliderWithSlidingTime:Percentage:phoneNbr:passwd:loginType:isChinatelecom:isBind:]0x101261728 CTPocket!-[ESPhoneLoginView passwordInputView:sliderWithSlidingTime:Percentage:phoneNbr:passwd:]0x101e73d10 CTPocket!-[PasswordInputView commitBtnAction:]0x1e7091300 UIKitCore!-[UIApplication sendAction:to:from:forEvent:]0x10400a288 CTPocket!-[UIApplication(AutoTrack) sa_sendAction:to:from:forEvent:]0x1e6b3a424 UIKitCore!-[UIControl sendAction:to:forEvent:]0x1e6b3a744 UIKitCore!-[UIControl _sendActionsForEvents:withEvent:]
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接下来我们使用 frida-trace 工具，对以上调用栈进行逐个跟踪并打印入参，最终确定 loginAuthCipherAsymmertric 参数在[ESLoginService loginWithPhoneNbr:type:code:isChinatelecom:slidingTime:percentage:success:failure:]方法里生成的，打开 IDA Pro 并找到该方法，代码如下：
id __cdecl -[ESLoginService loginWithPhoneNbr:type:code:isChinatelecom:slidingTime:percentage:success:failure:](ESLoginService *self, SEL a2, id a3, signed __int64 a4, id a5, id a6, id a7, id a8, id a9, id a10){ id v10; // x19 id v11; // x20 id v12; // x25 id v13; // x21 ESLoginService *v14; // x24 __int64 v15; // x1 __int64 v16; // x1 __int64 v17; // x1 __int64 v18; // x1 __int64 v19; // x1 __int64 v20; // x1 void *v21; // x0 __int64 v22; // x25 void *v23; // x0 unsigned int v24; // off signed int v25; // w8
v10 = a8; v11 = a7; v12 = a6; v13 = a5; v14 = self; objc_retain(a3, a2); objc_retain(a9, v15); objc_retain(a10, v16); objc_retain(v10, v17); objc_retain(v11, v18); objc_retain(v12, v19); objc_retain(v13, v20); v21 = objc_msgSend(&OBJC_CLASS___NSDate, "date"); v22 = objc_retainAutoreleasedReturnValue(v21); -[ESLoginService setRequestDate:](v14, "setRequestDate:", v22); objc_release(v22); v23 = (void *)((__int64 (__fastcall *)(void *))((char *)off_105153068 + 92708870))(&OBJC_CLASS___NSDateFormatter); objc_msgSend(v23, "init"); v24 = __ldar((unsigned int *)&dword_10577A424); if ( (unsigned int)&dword_10577A424 ) v25 = 7; else v25 = 34; JUMPOUT(__CS__, (char *)*(&off_105153070 + v25) - dword_1051531F0[v25]);}
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傻眼了了吧。 JUMPOUT，也就是经常逆向会遇到的跳表，需要手动恢复。在这，我们使用 frida stalker 来跟踪该函数。ts 代码如下：
var addr = 0x0000000029FD08 // loginWithPhoneNbr函数的起始地址var mainModule = Process.enumerateModules()[0];console.log(JSON.stringify(mainModule));var mainName: string = mainModule.name;var baseAddr = Module.findBaseAddress(mainName)!;Interceptor.attach(baseAddr.add(addr), { onEnter: function(args) { console.log(addr.toString(16), "= loginWithPhoneNbr onEnter ="); var tid = Process.getCurrentThreadId(); Stalker.follow(tid, { events: { call: true, // CALL instructions: yes please ret: false, // RET instructions exec: false, // all instructions: not recommended as it's block: false, // block executed: coarse execution trace compile: false // block compiled: useful for coverage }, transform: (iterator: StalkerArm64Iterator) => { let instruction = iterator.next(); const startAddress = instruction!.address; var isAppCode = startAddress.compare(baseAddr.add(addr)) >= 0 && startAddress.compare(baseAddr.add(addr).add(10000)) === -1; do { if (isAppCode) { if (instruction!.mnemonic === "bl") { iterator.putCallout((ctx) => { var arm64Context = ctx as Arm64CpuContext; console.log("bl x0 = " + new ObjC.Object(arm64Context.x0)) console.log("bl x1 = " + arm64Context.x1.readCString()) }); } } iterator.keep(); } while ((instruction = iterator.next()) !== null); } }) }, onLeave: function(retval) { console.log("retval:", new ObjC.Object(retval)) console.log(addr.toString(16), "= loginWithPhoneNbr onLeave ="); }});
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获取到的关键日志如下：
29fd08 = loginWithPhoneNbr onEnter =bl x0 = Utilsbl x1 = createRSAStringWithPhone:authentication:timestamp:slidingTime:percentage:bl x0 = s21NZBfNx8ndPADDLDJCxCUOdWo45EL8jNr6TnHcwKwfnahCFpLGjXkZkhbGj2CZODR3LVjabCRw6Li3SLcvLtA6g0meKbUTgQzANtn9y2ttg9Svj9flxj9k18Ju5EBjloSbdd4ee4o0rHgn9W0iSSDs4zwKsqm+rOxYDZFHgWI=bl x1 = autoreleasebl x0 = 0.000000bl x1 = nullbl x0 = 0bl x1 = nullbl x0 = NSMutableDictionarybl x1 = dictionarybl x0 = {}bl x1 = autoreleasebl x0 = {}bl x1 = setObject:forKey:bl x0 = { accountType = "";}bl x1 = setObjectOrNil:forKey:bl x0 = 222222bl x1 = copyWithZone:bl x0 = ESGlobalFactorybl x1 = sharedInstancebl x0 = <ESGlobalFactory: 0x282e568b0>bl x1 = sharedInstancebl x0 = <ESGlobalFactory: 0x282e568b0>bl x1 = deviceInfobl x0 = <ESDeviceInfo: 0x28225e120>bl x1 = deviceInfobl x0 = <ESDeviceInfo: 0x28225e120>bl x1 = uuidForDevicebl x0 = ddecc53e1fce414e9e89b6ea47e567e3bl x1 = autoreleasebl x0 = { accountType = ""; authentication = 222222;}bl x1 = setObjectOrNil:forKey:bl x0 = ddecc53e1fce414e9e89b6ea47e567e3bl x1 = copyWithZone:bl x0 = <ESDeviceInfo: 0x28225e120>bl x1 = releasebl x0 = <ESGlobalFactory: 0x282e568b0>bl x1 = releasebl x0 = { accountType = ""; authentication = 222222; deviceUid = ddecc53e1fce414e9e89b6ea47e567e3;}bl x1 = setObjectOrNil:forKey:bl x0 = 0bl x1 = copyWithZone:bl x0 = NSStringbl x1 = stringWithFormat:bl x0 = 4bl x1 = autoreleasebl x0 = { accountType = ""; authentication = 222222; deviceUid = ddecc53e1fce414e9e89b6ea47e567e3; isChinatelecom = 0;}bl x1 = setObjectOrNil:forKey:bl x0 = 4bl x1 = copyWithZone:bl x0 = { accountType = ""; authentication = 222222; deviceUid = ddecc53e1fce414e9e89b6ea47e567e3; isChinatelecom = 0; loginType = 4;}bl x1 = setObjectOrNil:forKey:bl x0 = UIDevicebl x1 = currentDevicebl x0 = <UIDevice: 0x2820598e0>bl x1 = currentDevicebl x0 = <UIDevice: 0x2820598e0>bl x1 = systemVersionbl x0 = 12.5.5bl x1 = X7Lyw9oGPgMDQbl x0 = { accountType = ""; authentication = 222222; deviceUid = ddecc53e1fce414e9e89b6ea47e567e3; isChinatelecom = 0; loginType = 4; phoneNum = 13245678901;}bl x1 = setObjectOrNil:forKey:bl x0 = 12.5.5bl x1 = 0��ו�bl x0 = <UIDevice: 0x2820598e0>bl x1 = 0��ו�bl x0 = { accountType = ""; authentication = 222222; deviceUid = ddecc53e1fce414e9e89b6ea47e567e3; isChinatelecom = 0; loginType = 4; phoneNum = 13245678901; systemVersion = "12.5.5";}bl x1 = setObjectOrNil:forKey:bl x0 = ESDataAccessFactorybl x1 = sharedInstancebl x0 = <ESDataAccessFactory: 0x280472460>bl x1 = sharedInstancebl x0 = <ESDataAccessFactory: 0x280472460>bl x1 = highFrequencyNetworkingManagerbl x0 = <ESNetworkingManager: 0x282e9cc90>bl x1 = highFrequencyNetworkingManagerbl x0 = <__NSStackBlock__: 0x16f4f0c28>bl x1 = highFrequencyNetworkingManagerbl x0 = <__NSStackBlock__: 0x16f4f0c88>bl x1 = retainbl x0 = 20220905003215bl x1 = retainbl x0 = 13245678901bl x1 = nullbl x0 = <ESNetworkingManager: 0x282e9cc90>bl x1 = postWithURLString:parameters:modifiParamsBlock:success:failure:bl x0 = { content = { attach = iPhone; fieldData = { accountType = ""; authentication = 222222; deviceUid = ddecc53e1fce414e9e89b6ea47e567e3; isChinatelecom = 0; loginAuthCipherAsymmertric = "s21NZBfNx8ndPADDLDJCxCUOdWo45EL8jNr6TnHcwKwfnahCFpLGjXkZkhbGj2CZODR3LVjabCRw6Li3SLcvLtA6g0meKbUTgQzANtn9y2ttg9Svj9flxj9k18Ju5EBjloSbdd4ee4o0rHgn9W0iSSDs4zwKsqm+rOxYDZFHgWI="; loginType = 4; phoneNum = 13245678901; systemVersion = "12.5.5"; }; }; headerInfos = { broadAccount = ""; broadToken = ""; clientType = "#9.4.0#channel50#iPhone 6#"; code = userLoginNormal; shopId = 20004; source = 120002; sourcePassword = TiqmIZ; timestamp = 20220905003218; token = ""; userLoginName = ""; };}bl x1 = a���
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结果
通过日志，我们可以发现 loginAuthCipherAsymmertric 参数是使用 Utils 类的 createRSAStringWithPhone:authentication:timestamp:slidingTime:percentage:方法生成的，伪代码如下：
id __cdecl +[Utils createRSAStringWithPhone:authentication:timestamp:slidingTime:percentage:](Utils_meta *self, SEL a2, id a3, id a4, id a5, id a6, id a7){ v7 = a7; v8 = a5; v9 = a4; v10 = a3; v11 = self; v12 = objc_retain(a6, a2); v14 = objc_retain(v7, v13); v16 = (void *)objc_retain(v8, v15); v18 = objc_retain(v9, v17); v20 = objc_retain(v10, v19); v21 = +[ESGlobalFactory sharedInstance](&OBJC_CLASS___ESGlobalFactory, "sharedInstance"); v22 = (void *)objc_retainAutoreleasedReturnValue(v21); v23 = v22; v24 = objc_msgSend(v22, "deviceInfo"); v25 = (void *)objc_retainAutoreleasedReturnValue(v24); v26 = v25; v27 = objc_msgSend(v25, "uuidForDevice"); v28 = objc_retainAutoreleasedReturnValue(v27); v29 = +[Utils substring:ToIndex:](&OBJC_CLASS___Utils, "substring:ToIndex:", v28, 12LL); v30 = objc_retainAutoreleasedReturnValue(v29); v31 = +[Utils deviceName](&OBJC_CLASS___Utils, "deviceName"); v32 = objc_retainAutoreleasedReturnValue(v31); v33 = v32; v34 = +[Utils substring:ToIndex:](&OBJC_CLASS___Utils, "substring:ToIndex:", v32, 10LL); v35 = objc_retainAutoreleasedReturnValue(v34); v36 = objc_msgSend(&OBJC_CLASS___UIDevice, "currentDevice"); v37 = (void *)objc_retainAutoreleasedReturnValue(v36); v38 = v37; v39 = objc_msgSend(v37, "systemVersion"); v40 = objc_retainAutoreleasedReturnValue(v39); objc_release(v38); v41 = +[Utils substring:ToIndex:](&OBJC_CLASS___Utils, "substring:ToIndex:", v40, 5LL); v42 = objc_retainAutoreleasedReturnValue(v41); objc_release(v40); v43 = (void *)objc_alloc(&OBJC_CLASS___NSDateFormatter); v44 = objc_msgSend(v43, "init"); v45 = v44; v46 = v44; objc_msgSend(v44, "setDateFormat:", CFSTR("yyyyMMddHHmmss")); v47 = (void *)objc_alloc(&OBJC_CLASS___NSLocale); v48 = objc_msgSend(v47, "initWithLocaleIdentifier:", CFSTR("en_US")); objc_msgSend(v45, "setLocale:", v48); v49 = objc_msgSend(v16, "stringByReplacingOccurrencesOfString:withString:", CFSTR(":"), &stru_10480C358); v50 = objc_retainAutoreleasedReturnValue(v49); objc_release(v16); v51 = +[Utils substring:ToIndex:](&OBJC_CLASS___Utils, "substring:ToIndex:", v50, 14LL); v52 = objc_retainAutoreleasedReturnValue(v51); v53 = v52; v54 = v52; v55 = objc_msgSend(v11, "substring:ToIndex:", v12, 4LL); v56 = objc_retainAutoreleasedReturnValue(v55); v57 = objc_msgSend(v11, "substring:ToIndex:", v14, 2LL); v58 = objc_retainAutoreleasedReturnValue(v57); v59 = objc_msgSend(v11, "substring:ToIndex:", v18, 6LL); v60 = objc_retainAutoreleasedReturnValue(v59); v61 = objc_msgSend(v11, "substring:ToIndex:", v20, 11LL); v62 = objc_retainAutoreleasedReturnValue(v61); v63 = objc_msgSend( &OBJC_CLASS___NSString, "stringWithFormat:", CFSTR("%@%@%@%@%@%@%@%@"), v35, v42, v30, v62, v53, v60, v56, v58); v64 = objc_retainAutoreleasedReturnValue(v63); v65 = +[Utils loginRsaKey2](&OBJC_CLASS___Utils, "loginRsaKey2"); v66 = objc_retainAutoreleasedReturnValue(v65); v67 = v66; v68 = +[RSAEncryptor encryptString:publicKey:](&OBJC_CLASS___RSAEncryptor, "encryptString:publicKey:", v64, v66); v69 = objc_retainAutoreleasedReturnValue(v68); return (id)objc_autoreleaseReturnValue(v69);}
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这就是生成 loginAuthCipherAsymmertric 的最终函数。
End
阅读此文档的过程中遇到任何问题，请关注公众号【移动端Android和iOS开发技术分享】或加 QQ 群【812546729】
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