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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) { }}点击登录后，获取到的日志如下：
-[NSMu```
tableURLRequest 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]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) { }}获取到的堆栈信息如下：
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:]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：
__cdecl `
-ESLoginService loginWithPhoneNbr:type:code:isChinatelecom:slidingTime:percentage:success:failure:{ 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:; 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]);}
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：12345678910111213141516171819202122232425262728293031323334353637383940var 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 ="); }});获取到的关键日志如下：12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788899091929394959697989910010110210310410510610710810911011111211311411511611711811912012112212312412512612712812913013113213313413513613713813914014114214314414514614714814915015115229fd08 = 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 = 