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】

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：

-[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&currentPage=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&currentPage=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：

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:]

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]);
}

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 =");
    }
});

获取到的关键日志如下：

29fd08 = loginWithPhoneNbr onEnter =
bl x0 = Utils
bl x1 = createRSAStringWithPhone:authentication:timestamp:slidingTime:percentage:
bl x0 = s21NZBfNx8ndPADDLDJCxCUOdWo45EL8jNr6TnHcwKwfnahCFpLGjXkZkhbGj2CZODR3LVjabCRw6Li3SLcvLtA6g0meKbUTgQzANtn9y2ttg9Svj9flxj9k18Ju5EBjloSbdd4ee4o0rHgn9W0iSSDs4zwKsqm+rOxYDZFHgWI=
bl x1 = autorelease
bl x0 = 0.000000
bl x1 = null
bl x0 = 0
bl x1 = null
bl x0 = NSMutableDictionary
bl x1 = dictionary
bl x0 = {
}
bl x1 = autorelease
bl x0 = {
}
bl x1 = setObject:forKey:
bl x0 = {
    accountType = "";
}
bl x1 = setObjectOrNil:forKey:
bl x0 = 222222
bl x1 = copyWithZone:
bl x0 = ESGlobalFactory
bl x1 = sharedInstance
bl x0 = <ESGlobalFactory: 0x282e568b0>
bl x1 = sharedInstance
bl x0 = <ESGlobalFactory: 0x282e568b0>
bl x1 = deviceInfo
bl x0 = <ESDeviceInfo: 0x28225e120>
bl x1 = deviceInfo
bl x0 = <ESDeviceInfo: 0x28225e120>
bl x1 = uuidForDevice
bl x0 = ddecc53e1fce414e9e89b6ea47e567e3
bl x1 = autorelease
bl x0 = {
    accountType = "";
    authentication = 222222;
}
bl x1 = setObjectOrNil:forKey:
bl x0 = ddecc53e1fce414e9e89b6ea47e567e3
bl x1 = copyWithZone:
bl x0 = <ESDeviceInfo: 0x28225e120>
bl x1 = release
bl x0 = <ESGlobalFactory: 0x282e568b0>
bl x1 = release
bl x0 = {
    accountType = "";
    authentication = 222222;
    deviceUid = ddecc53e1fce414e9e89b6ea47e567e3;
}
bl x1 = setObjectOrNil:forKey:
bl x0 = 0
bl x1 = copyWithZone:
bl x0 = NSString
bl x1 = stringWithFormat:
bl x0 = 4
bl x1 = autorelease
bl x0 = {
    accountType = "";
    authentication = 222222;
    deviceUid = ddecc53e1fce414e9e89b6ea47e567e3;
    isChinatelecom = 0;
}
bl x1 = setObjectOrNil:forKey:
bl x0 = 4
bl x1 = copyWithZone:
bl x0 = {
    accountType = "";
    authentication = 222222;
    deviceUid = ddecc53e1fce414e9e89b6ea47e567e3;
    isChinatelecom = 0;
    loginType = 4;
}
bl x1 = setObjectOrNil:forKey:
bl x0 = UIDevice
bl x1 = currentDevice
bl x0 = <UIDevice: 0x2820598e0>
bl x1 = currentDevice
bl x0 = <UIDevice: 0x2820598e0>
bl x1 = systemVersion
bl x0 = 12.5.5
bl x1 = X7Lyw9oGPgMDQ
bl x0 = {
    accountType = "";
    authentication = 222222;
    deviceUid = ddecc53e1fce414e9e89b6ea47e567e3;
    isChinatelecom = 0;
    loginType = 4;
    phoneNum = 13245678901;
}
bl x1 = setObjectOrNil:forKey:
bl x0 = 12.5.5
bl 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 = ESDataAccessFactory
bl x1 = sharedInstance
bl x0 = <ESDataAccessFactory: 0x280472460>
bl x1 = sharedInstance
bl x0 = <ESDataAccessFactory: 0x280472460>
bl x1 = highFrequencyNetworkingManager
bl x0 = <ESNetworkingManager: 0x282e9cc90>
bl x1 = highFrequencyNetworkingManager
bl x0 = <__NSStackBlock__: 0x16f4f0c28>
bl x1 = highFrequencyNetworkingManager
bl x0 = <__NSStackBlock__: 0x16f4f0c88>
bl x1 = retain
bl x0 = 20220905003215
bl x1 = retain
bl x0 = 13245678901
bl x1 = null
bl 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���

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);
}

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】