【iOS 逆向】某不知名 App 越狱检测
作者：小陈
- 2022 年 9 月 11 日 四川
本文字数：8482 字
阅读完需：约 28 分钟
1.目标
此篇文本为入门文章，大家莫抱过多期望。此文章的目的是教大家如何从 UI 入手，去定位自己想要的东西。
2.操作环境
mac 系统
frida-ios-dump：砸壳
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
启动 App 后，界面如下图：
分析过程
从界面可以看出，App 检测到越狱后，会弹出一个弹窗，文案为越狱手机存在安全风险，做 iOS 开发的都知道，最终这文案显示前，会调用 UILabel 类的 setText:方法。我们 trace 该方法并打印堆栈:
js 代码：
{onEnter(log, args, state) {log(`-[UILabel setText:${new ObjC.Object(args[2])}]`);log('UILabel setText called from:\n' +Thread.backtrace(this.context, Backtracer.ACCURATE).map(DebugSymbol.fromAddress).join('\n') + '\n');},onLeave(log, retval, state) {}}
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关键日志如下：
-[UILabel setText:越狱手机存在安全风险]UILabel setText called from:0x1eaa7d0f4 UIKitCore!-[_UIAlertControllerView _updateMessageLabelContents]0x1eaa756f8 UIKitCore!-[_UIAlertControllerView _prepareMesssageLabel]0x1eaa750f8 UIKitCore!-[_UIAlertControllerView _prepareViewsAndAddConstraints]0x1eaa75048 UIKitCore!-[_UIAlertControllerView setAlertController:]0x1eaa61740 UIKitCore!-[UIAlertController loadView]0x1ead35ed8 UIKitCore!-[UIViewController loadViewIfRequired]0x1ead36628 UIKitCore!-[UIViewController view]0x1ead4ddd4 UIKitCore!-[UIViewController _setPresentationController:]0x1ead461f4 UIKitCore!-[UIViewController _presentViewController:modalSourceViewController:presentationController:animationController:interactionController:completion:]0x1ead47ccc UIKitCore!-[UIViewController _presentViewController:withAnimationController:completion:]0x1ead4a3a8 UIKitCore!__63-[UIViewController _presentViewController:animated:completion:]_block_invoke0x1ead4a8a4 UIKitCore!-[UIViewController _performCoordinatedPresentOrDismiss:animated:]0x1ead4a300 UIKitCore!-[UIViewController _presentViewController:animated:completion:]0x1ead4a560 UIKitCore!-[UIViewController presentViewController:animated:completion:]0x10128253c GeneralApp!0xd253c (0x1000d253c)0x1be344a38 libdispatch.dylib!_dispatch_call_block_and_release
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使用 frida-ios-dump 砸壳后，再使用 IDA Pro 编译 ipa 文件。
跳转到内存 0x1000d253c 位置
再按 F5:
__int64 __fastcall sub_1000D24D4(_QWORD *a1){void *v1; // x19__int64 v2; // x20void **v4; // [xsp+8h] [xbp-38h]__int64 v5; // [xsp+10h] [xbp-30h]__int64 (__fastcall *v6)(); // [xsp+18h] [xbp-28h]void *v7; // [xsp+20h] [xbp-20h]__int64 v8; // [xsp+28h] [xbp-18h]v1 = (void *)a1[4];v2 = a1[5];v4 = _NSConcreteStackBlock;v5 = 3254779904LL;v6 = sub_1000D2554;v7 = &unk_101A29970;v8 = objc_retain(a1[6]);objc_msgSend(v1, "presentViewController:animated:completion:", v2, 1LL, &v4);return objc_release(v8);}
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查找 sub_1000D24D4 函数的交叉引用，一层一层往上找，最终找到如下函数：
void __cdecl -[UIViewController cft_presentViewController:presentType:presentCompletionHandler:dismissCompleteHandler:](UIViewController *self, SEL a2, id a3, unsigned __int64 a4, id a5, id a6){id v6; // x21id v7; // x20UIViewController *v8; // x24void *v9; // x19__int64 v10; // x20__int64 v11; // x21void *v12; // x0__int64 v13; // x22dispatch_semaphore_t v14; // x23void *v15; // x0void *v16; // x24void *v17; // x0void *v18; // x0void *v19; // x27void *v20; // x0__int64 v21; // x28void *v22; // x0void *v23; // x0void *v24; // x25void *v25; // x0__int64 v26; // x26__int64 v27; // [xsp+8h] [xbp-A8h]void **v28; // [xsp+10h] [xbp-A0h]__int64 v29; // [xsp+18h] [xbp-98h]__int64 (__fastcall *v30)(__int64); // [xsp+20h] [xbp-90h]void *v31; // [xsp+28h] [xbp-88h]__int64 v32; // [xsp+30h] [xbp-80h]__int64 v33; // [xsp+38h] [xbp-78h]__int64 v34; // [xsp+40h] [xbp-70h]UIViewController *v35; // [xsp+48h] [xbp-68h]__int64 v36; // [xsp+50h] [xbp-60h]__int64 v37; // [xsp+58h] [xbp-58h]v6 = a6;v7 = a5;v8 = self;v9 = (void *)objc_retain(a3);v10 = objc_retain(v7);v11 = objc_retain(v6);v37 = 0LL;v12 = objc_msgSend(v9,"aspect_hookSelector:withOptions:usingBlock:error:","viewDidDisappear:",0LL,&off_101A2BF98,&v37);objc_unsafeClaimAutoreleasedReturnValue(v12);v13 = objc_retain(v37);if ( !v13 ){v14 = dispatch_semaphore_create(0LL);v28 = _NSConcreteStackBlock;v29 = 3254779904LL;v30 = sub_1000D23A0;v31 = &unk_101A2BFB8;v32 = objc_retain(v9);v33 = objc_retain(v11);v27 = objc_retain(v14);v34 = v27;v35 = v8;v36 = objc_retain(v10);v15 = objc_msgSend(&OBJC_CLASS___NSBlockOperation, "blockOperationWithBlock:", &v28);v16 = (void *)objc_retainAutoreleasedReturnValue(v15);v17 = objc_msgSend((void *)qword_101F71BF8, "operations");v18 = (void *)objc_retainAutoreleasedReturnValue(v17);v19 = v18;v20 = objc_msgSend(v18, "lastObject");v21 = objc_retainAutoreleasedReturnValue(v20);objc_release(v21);objc_release(v19);if ( v21 ){v22 = objc_msgSend((void *)qword_101F71BF8, "operations");v23 = (void *)objc_retainAutoreleasedReturnValue(v22);v24 = v23;v25 = objc_msgSend(v23, "lastObject");v26 = objc_retainAutoreleasedReturnValue(v25);objc_msgSend(v16, "addDependency:", v26);objc_release(v26);objc_release(v24);}objc_msgSend((void *)qword_101F71BF8, "addOperation:", v16);objc_release(v16);objc_release(v36);objc_release(v34);objc_release(v33);objc_release(v32);objc_release(v27);}objc_release(v13);objc_release(v11);objc_release(v10);objc_release(v9);}
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接下来，同时跟踪 UILabel 的 setText:方法和 UIViewController 的 cft_presentViewController:presentType:presentCompletionHandler:dismissCompleteHandler:方法，获取到日志如下：
-[UIViewController cft_presentViewController:0x104928e00 presentType:0x1 presentCompletionHandler:0x16ec4e5a8 dismissCompleteHandler:0x16ec4e580]UIViewController cft_presentViewController called from:0x1012b9fdc GeneralApp!+[CFTAlertPresentController presentAlertController:presentCompletionHandler:dismissCompleteHandler:]0x1012d464c GeneralApp!-[LaunchingViewController start]0x1012d3360 GeneralApp!0x123360 (0x100123360)0x1be3457d4 libdispatch.dylib!_dispatch_client_callout0x1be2f3c1c libdispatch.dylib!_dispatch_lane_barrier_sync_invoke_and_complete0x1012d3310 GeneralApp!0x123310 (0x100123310)0x1012b9978 GeneralApp!0x109978 (0x100109978)0x1eb76ad1c UIKitCore!-[UIViewAnimationBlockDelegate _didEndBlockAnimation:finished:context:]0x1eb741a74 UIKitCore!-[UIViewAnimationState sendDelegateAnimationDidStop:finished:]0x1eb742048 UIKitCore!-[UIViewAnimationState animationDidStop:finished:]0x1c2e573c8 QuartzCore!CA::Layer::run_animation_callbacks(void*)0x1be3457d4 libdispatch.dylib!_dispatch_client_callout0x1be2f3008 libdispatch.dylib!_dispatch_main_queue_callback_4CF$VARIANT$mp0x1be898b20 CoreFoundation!__CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__0x1be893a58 CoreFoundation!__CFRunLoopRun0x1be892fb4 CoreFoundation!CFRunLoopRunSpecific-[UILabel setText:您的设备不安全]UILabel setText called from:0x1eaa7cfe8 UIKitCore!-[_UIAlertControllerView _updateTitleLabelContents]0x1eaa75544 UIKitCore!-[_UIAlertControllerView _prepareTitleLabel]0x1eaa750e8 UIKitCore!-[_UIAlertControllerView _prepareViewsAndAddConstraints]0x1eaa75048 UIKitCore!-[_UIAlertControllerView setAlertController:]0x1eaa61740 UIKitCore!-[UIAlertController loadView]0x1ead35ed8 UIKitCore!-[UIViewController loadViewIfRequired]0x1ead36628 UIKitCore!-[UIViewController view]0x1ead4ddd4 UIKitCore!-[UIViewController _setPresentationController:]0x1ead461f4 UIKitCore!-[UIViewController _presentViewController:modalSourceViewController:presentationController:animationController:interactionController:completion:]0x1ead47ccc UIKitCore!-[UIViewController _presentViewController:withAnimationController:completion:]0x1ead4a3a8 UIKitCore!__63-[UIViewController _presentViewController:animated:completion:]_block_invoke0x1ead4a8a4 UIKitCore!-[UIViewController _performCoordinatedPresentOrDismiss:animated:]0x1ead4a300 UIKitCore!-[UIViewController _presentViewController:animated:completion:]0x1ead4a560 UIKitCore!-[UIViewController presentViewController:animated:completion:]0x10128253c GeneralApp!0xd253c (0x1000d253c)0x1be344a38 libdispatch.dylib!_dispatch_call_block_and_release-[UILabel setText:越狱手机存在安全风险]UILabel setText called from:0x1eaa7d0f4 UIKitCore!-[_UIAlertControllerView _updateMessageLabelContents]0x1eaa756f8 UIKitCore!-[_UIAlertControllerView _prepareMesssageLabel]0x1eaa750f8 UIKitCore!-[_UIAlertControllerView _prepareViewsAndAddConstraints]0x1eaa75048 UIKitCore!-[_UIAlertControllerView setAlertController:]0x1eaa61740 UIKitCore!-[UIAlertController loadView]0x1ead35ed8 UIKitCore!-[UIViewController loadViewIfRequired]0x1ead36628 UIKitCore!-[UIViewController view]0x1ead4ddd4 UIKitCore!-[UIViewController _setPresentationController:]0x1ead461f4 UIKitCore!-[UIViewController _presentViewController:modalSourceViewController:presentationController:animationController:interactionController:completion:]0x1ead47ccc UIKitCore!-[UIViewController _presentViewController:withAnimationController:completion:]0x1ead4a3a8 UIKitCore!__63-[UIViewController _presentViewController:animated:completion:]_block_invoke0x1ead4a8a4 UIKitCore!-[UIViewController _performCoordinatedPresentOrDismiss:animated:]0x1ead4a300 UIKitCore!-[UIViewController _presentViewController:animated:completion:]0x1ead4a560 UIKitCore!-[UIViewController presentViewController:animated:completion:]0x10128253c GeneralApp!0xd253c (0x1000d253c)0x1be344a38 libdispatch.dylib!_dispatch_call_block_and_release
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在 cft_presentViewController:presentType:presentCompletionHandler:dismissCompleteHandler:方法的调用栈，发现[LaunchingViewController start]方法，使用 ida pro 查看该函数：
void __cdecl -[LaunchingViewController start](LaunchingViewController *self, SEL a2){if ( !(~LODWORD(self->_launchAchieveOption) & 0x1FLL) ){v2 = self;self->_launchAchieveOption = 0LL;v3 = ((id (__cdecl *)(GuaTabBarController_meta *, SEL))objc_msgSend)((GuaTabBarController_meta *)&OBJC_CLASS___GuaTabBarController,"shareTabBarController");v4 = objc_retainAutoreleasedReturnValue(v3);v23 = _NSConcreteStackBlock;v24 = 3254779904LL;v25 = sub_100124684;v26 = &unk_101A2BC20;v5 = (void *)objc_retain(v4);v27 = v5;v28 = v2;+[NaviService naviModelWithNaviRoot:withNaviHead:withSourceFrom:ret:](&OBJC_CLASS___NaviService,"naviModelWithNaviRoot:withNaviHead:withSourceFrom:ret:",_NSConcreteStackBlock,3254779904LL,sub_100124684,&unk_101A2BC20);if ( v2->_adDetailDisplayController ){v6 = objc_msgSend(v5, "viewControllers", v23, v24, v25, v26);v7 = (void *)objc_retainAutoreleasedReturnValue(v6);v8 = v7;v9 = objc_msgSend(v7, "objectAtIndexedSubscript:", 0LL, v23, v24, v25, v26);v10 = (void *)objc_retainAutoreleasedReturnValue(v9);objc_msgSend(v10, "pushViewController:animated:", v2->_adDetailDisplayController, 1LL, v23, v24, v25, v26);}v11 = objc_msgSend(&OBJC_CLASS___UIApplication, "sharedApplication", v23, v24, v25, v26);v12 = (void *)objc_retainAutoreleasedReturnValue(v11);v13 = v12;v14 = objc_msgSend(v12, "delegate", v23, v24, v25, v26);v15 = (void *)objc_retainAutoreleasedReturnValue(v14);v16 = v15;v17 = objc_msgSend(v15, "window", v23, v24, v25, v26);v18 = (void *)objc_retainAutoreleasedReturnValue(v17);objc_msgSend(v18, "setRootViewController:", v5, v23, v24, v25, v26);if ( (unsigned int)+[CFTJailBreakJudge deviceIsJailBreak](&OBJC_CLASS___CFTJailBreakJudge,"deviceIsJailBreak",v23,v24,v25,v26) ){v19 = objc_msgSend(&OBJC_CLASS___UIAlertController,"alertControllerWithTitle:message:preferredStyle:",CFSTR("您的设备不安全"),CFSTR("越狱手机存在安全风险"),1LL,v23,v24,v25,v26);v20 = (void *)objc_retainAutoreleasedReturnValue(v19);v21 = objc_msgSend(&OBJC_CLASS___UIAlertAction,"actionWithTitle:style:handler:",CFSTR("确定"),0LL,0LL,v23,v24,v25,v26);v22 = objc_retainAutoreleasedReturnValue(v21);objc_msgSend(v20, "addAction:", v22, v23, v24, v25, v26);+[CFTAlertPresentController presentAlertController:](&OBJC_CLASS___CFTAlertPresentController,"presentAlertController:",v20,v23,v24,v25,v26);}}}
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从函数中可发现越狱检测函数为[CFTJailBreakJudge deviceIsJailBreak]：
bool __cdecl +[CFTJailBreakJudge deviceIsJailBreak](CFTJailBreakJudge_meta *self, SEL a2){CFTJailBreakJudge_meta *v2; // x20void *v3; // x0__int64 v4; // x0void *v5; // x0void *v6; // x19void *v7; // x0void *v8; // x22__int64 v9; // x25unsigned __int64 v10; // x26uint32_t v11; // w0uint32_t v12; // w20uint32_t v13; // w21void *v14; // x25const char *v15; // x0void *v16; // x25char v17; // w26_BOOL8 v18; // x20bool result; // w0__int128 v20; // [xsp+0h] [xbp-140h]__int128 v21; // [xsp+10h] [xbp-130h]__int128 v22; // [xsp+20h] [xbp-120h]__int128 v23; // [xsp+30h] [xbp-110h]char v24; // [xsp+40h] [xbp-100h]const __CFString *v25; // [xsp+C0h] [xbp-80h]const __CFString *v26; // [xsp+C8h] [xbp-78h]const __CFString *v27; // [xsp+D0h] [xbp-70h]const __CFString *v28; // [xsp+D8h] [xbp-68h]const __CFString *v29; // [xsp+E0h] [xbp-60h]__int64 v30; // [xsp+E8h] [xbp-58h]v2 = self;v25 = CFSTR("/Applications/Cydia.app");v26 = CFSTR("/Library/MobileSubstrate/MobileSubstrate.dylib");v27 = CFSTR("/bin/bash");v28 = CFSTR("/usr/sbin/sshd");v29 = CFSTR("/etc/apt");v3 = objc_msgSend(&OBJC_CLASS___NSArray, "arrayWithObjects:count:", &v25, 5LL);v4 = objc_retainAutoreleasedReturnValue(v3);v20 = 0u;v21 = 0u;v22 = 0u;v23 = 0u;v5 = (void *)objc_retain(v4);v6 = v5;v7 = objc_msgSend(v5, "countByEnumeratingWithState:objects:count:", &v20, &v24, 16LL, 0LL);if ( v7 ){v8 = v7;v9 = *(_QWORD *)v21;while ( 2 ){v10 = 0LL;do{if ( *(_QWORD *)v21 != v9 )objc_enumerationMutation(v6);if ( (unsigned __int64)objc_msgSend(v2,"permissionForFile:",*(_QWORD *)(*((_QWORD *)&v20 + 1) + 8 * v10),(_QWORD)v20) & 1 ){objc_release(v6);goto LABEL_16;}++v10;}while ( v10 < (unsigned __int64)v8 );v8 = objc_msgSend(v6, "countByEnumeratingWithState:objects:count:", &v20, &v24, 16LL, (_QWORD)v20);if ( v8 )continue;break;}}objc_release(v6);if ( !((unsigned __int64)objc_msgSend(v2, "permissionForFile:", CFSTR("/User/Applications/"), (_QWORD)v20) & 1) ){v11 = _dyld_image_count();if ( !v11 ){LABEL_14:v18 = getenv("DYLD_INSERT_LIBRARIES") != 0LL;goto LABEL_17;}v12 = v11;v13 = 0;while ( 1 ){v14 = (void *)objc_alloc(&OBJC_CLASS___NSString);v15 = _dyld_get_image_name(v13);v16 = objc_msgSend(v14, "initWithUTF8String:", v15, (_QWORD)v20);v17 = (unsigned __int64)objc_msgSend(v16, "containsString:", CFSTR("MobileSubstrate.dylib"), (_QWORD)v20);objc_release(v16);if ( v17 & 1 )break;if ( v12 == ++v13 )goto LABEL_14;}}LABEL_16:v18 = 1;LABEL_17:return v18;}
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结果
1、检测以下路径是否存在：
/Applications/Cydia.app
/Library/MobileSubstrate/MobileSubstrate.dylib
/bin/bash
/usr/sbin/sshd
/etc/apt
2、如果路径/User/Applications/不存在，检测 getenv("DYLD_INSERT_LIBRARIES")是否存在
3、如果路径/User/Applications/不存在，检测当前现在在运行的动态库是否包含 MobileSubstrate.dylib
End
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