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# Tag: Security

## Even more on MySQL password security

MySQL Security June 8, 2009August 10, 2009

This post follows Ronald Bradford’s More Basic MySQL Security, and Lenz Grimmer’s Basic MySQL Security: Providing passwords on the command line and More on MySQL password security.

In Ronald’s post I’ve argued that passwords provided on command line are visible in plaintext on “ps aux”. Lenz has argued that this is incorrect, providing the source code to support that. Giuseppe commenting that this has been fixed since 2002. Later on, Lenz shows that passwords are visible in plaintext on OpenSolaris, Solaris and variants of BSD and SysV.

Mental note: old habits die hard; I must remember to revisit issues from time to time.

#### Centralizing

Back to the question: why use a file to store your password, and not provide it on command line?

Continue reading » “Even more on MySQL password security”

## Blocking user accounts

MySQL openark kit Security March 5, 2009February 8, 2011

A long time missing feature in MySQL is temporarily blocking accounts: denying a user to log in, without affecting any other of her privileges.

There is no such privilege as ‘LOGIN’ in the grants table, as the ability to log in is the most basic one MySQL allows. This basic privilege is called USAGE.

I’ll present a hack around this, one which oak-block-account implements. Before presenting the hack, lets lay down some requirements:

- A user can be blocked from logging in to MySQL.
- Such a blocked user can later be ‘released’, re-enabling him to log in.
- It should be possible to determine if a certain user is currently blocked or not.

Continue reading » “Blocking user accounts”

## `;`.`*`.`.` is a valid column name

MySQL Security Syntax February 12, 2009February 12, 2009

And the following query:

>     SELECT `;`.`*`.`.` FROM `;`.`*`;

is valid as well. So are the following:

>     DROP DATABASE IF EXISTS `;`;
>     CREATE DATABASE `;`;
>     CREATE TABLE `;`.`*` (`.` INT);
>     CREATE TABLE `;`.```` (`.` INT);
>     CREATE TABLE `;`.`$(ls)` (`.` INT);

Continue reading » “`;`.`*`.`.` is a valid column name”

## MySQL security: data integrity issues

MySQL Configuration Security sql_mode January 21, 2009

MySQL’s security model is not as elaborate as other popular databases. It’s missing quite a lot.

I wish to point out what I think are some very disturbing security holes, which may affect the database integrity.

This post is not about Roles, Kerberos, IPs and such. It’s about simple MySQL features, which allow common, unprivileged users, to break data integrity by using unprotected session variables.

I will consider three such issues.

Continue reading » “MySQL security: data integrity issues”

## Triggers Use Case Compilation, Part I

MySQL Security Triggers January 5, 2009January 16, 2009

I’ve run by quite a few triggers lately on production systems. In previous posts, I’ve written about problems solved with triggers. So here’s a compilation of some solutions based on triggers; and some problems which are not (yet?) solvable due to current triggers limitations.

Triggers can be used to:

- Maintain integrity
- Enhance security
- Enhance logging
- Assist with archiving
- Restrict table size
- Manage caching
- Manage counters

Triggers are not fast. In fact, they can add quite an overhead if misused. Some of the triggers presented here are known to work on real life production systems, though, and work well. But make sure you benchmark before embarking on extensive application changes. Continue reading » “Triggers Use Case Compilation, Part I”

## Using triggers to block malicious code: an example

MySQL Security SQL Triggers January 1, 2009

Web applications face constant exploitation attempts. Those with a user base must keep their users’ private data, well… private.

While the MySQL security model allows restricting users access to databases, tables and even columns, it has no built in feature for restricting the rows access within the given table.

One cannot allow a user to only update rows 0 through 99, but restrict that user from updating rows 100 to 199. Such restrictions are usually managed in the application level, by adding a necessary “… AND filtering_column = some_value…”

Many web application have the notion of an ‘admin’ account, or several such accounts, which provide greater control over the application. The ‘admin’ account is one account to which many attacks are targeted. One such attack is an attempt to modify the admin’s password, such that the attacker can later log in with and access restricted data. Continue reading » “Using triggers to block malicious code: an example”

## Dangers of skip-grant-tables

MySQL Configuration Security November 13, 2008December 13, 2008

When MySQL’s root password is lost and must be reset, there are two popular ways to create a new password. One of the options is far too popular, in my opinion.

The preferred way of setting a root’s password is by using an init-file. The process for doing this is well explained in MySQL’s manual. Using this method requires creating a simple text file, in which the required

`GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFY BY '****' WIth GRANT OPTION;`

(or, alternatively, `SET PASSWORD ...`) statement is written.

An entry must be written to my.cnf, or supplied via command line parameters:

`init-file=/tmp/my-init-file.sql`

MySQL must then be restarted. Upon restart, and before opening any outside connections, the init-file is executed. Once MySQL is up and running, the init-file entry should be dropped. Continue reading » “Dangers of skip-grant-tables”