Today, oCERT published advisory 2015-003 describing a TLS vulnerability in MySQL and derivative products. The content isn’t exactly news – it is documented legacy behavior and the subject of an earlier blog post describing how MySQL Server 5.7 solves the problem. That said, the efforts of Duo Security are certainly appreciated and welcomed – it provides a meaningful context to discuss how to properly harden existing MySQL 5.5 and 5.6 deployments, as well as frame a discussion on potential changes in these versions to increase security.
Tag Archives: MySQL 5.7
Locking accounts in MySQL 5.7
I’ve written previously about use cases where having accounts which cannot be used to establish client connections are useful. There are various hacks to accomplish this with legacy versions (insert invalid password hash into mysql.user table, etc.), and we introduced the mysql_no_login authentication plugin for this very purpose. Now as of MySQL 5.7.6, account locking gets native support through the ACCOUNT LOCK clause of CREATE USER and ALTER USER commands. This post revisits the use cases which drove this feature and the implementation details.
Continue reading Locking accounts in MySQL 5.7
Practical P_S: Which TLS ciphers are connections using?
As noted in an earlier post, MySQL Server 5.7 prefers and enables SSL/TLS connections by default. That’s great and useful progress towards secure connections, but we know that not all SSL/TLS ciphers are created equal – some are older and more vulnerable. Furthermore, some recent vulnerabilities rely on the ability to negotiate less-secure ciphers during the handshake. Monitoring which ciphers are used can help identify connections using low-grade ciphers, but also to build an appropriate restricted cipher list. Using improvements to PERFORMANCE_SCHEMA introduced in 5.7, you can now easily do this – and this post will show you how.
Continue reading Practical P_S: Which TLS ciphers are connections using?
Improved ALTER USER syntax support in 5.7
Complimenting the expanded CREATE USER syntax introduced in MySQL Server 5.7.6 is more useful ALTER USER syntax. Before MySQL Server 5.7.6, ALTER USER could only be used to expire a user’s password. That’s pretty limited. With changes made in MySQL Server 5.7.6, a better distinction is made between privilege-level attributes (those which are managed via GRANT and REVOKE statements) and account-level attributes (those managed using CREATE USER and ALTER USER statements). MySQL has a long history of confusing these – for example, requiring a GRANT command to set account resource limits or require SSL. This all changes for the better in MySQL Server 5.7 – here’s how: Continue reading Improved ALTER USER syntax support in 5.7
Implications of TLS plans for third-party products
As I wrote earlier, we want the default experience in MySQL 5.7 to be secure by default. Part of this includes securing connections by automatically creating key material and using TLS for connections where possible. This may have some significant implications for third-party software – especially products which depend upon capturing, evaluating and/or redirecting client/server traffic at the network level. This blog post is intended to highlight for developers and users of such products potential issues they may want to consider or address during the pre-GA period for MySQL Server 5.7. Continue reading Implications of TLS plans for third-party products
SSL/TLS in MySQL 5.7
MySQL 5.7 aims to be the most secure MySQL Server release ever, and that means some significant changes in SSL/TLS. This post aims to tie together individual enhancements introduced over the span of several Development Milestone Releases (DMRs) into the larger initiative. In the simplest terms, we hope to have a minimal TLS configuration enabled by default, and for connections to prefer TLS by default. Let’s dig into the various aspects of this:
Building a better CREATE USER command
Prior to MySQL 5.7, the CREATE USER command had a number of limitations:
- No way to set both authentication plugin and password
- No way to disable a user
- No way to define user resource limitations
- No way to set a non-default password expiration policy
- No way to require SSL/x509
All of these things could be done through other means, but typically involved other statements, such as GRANT commands. Starting with MySQL 5.7.6, these can all be done through a new and improved CREATE USER syntax:
Emulating roles with expanded proxy user support in 5.7.7
MySQL has provided support for proxy users since version 5.5, but the roles-like capabilities offered have been largely unnoticed until recently. Part of that has been due to limitations on which types of accounts could leverage proxy user capabilities. This changes with the release of MySQL Server 5.7.7 (Release Candidate), which includes support for proxy user mapping for the standard mysql_native_password and sha256_password authentication plugins. This post will introduce the new functionality and explain how to leverage it to emulate certain features of roles without any need for PAM or external authentication systems.
Continue reading Emulating roles with expanded proxy user support in 5.7.7
Batch mode and expired passwords
A series of related discussions triggered by difficulty in setting passwords via scripts using the mysql command-line client when an account has an expired password caused me to look into the interaction between expired passwords and batch mode, and this blog post resulted. I hope it’s a useful explanation of the behavior and the workaround to those troubled by it, and amplifies the excellent documentation in the user manual. Continue reading Batch mode and expired passwords
Redefining –ssl option
[UPDATE: Please see related post regarding oCERT assessment 2015-003.]
MySQL clients have long had a –ssl option. Casual users may think specifying this option will cause clients to secure connections using SSL. That is not the case: Continue reading Redefining –ssl option