Database Security

Databases introduce a number of unique security requirements for their users and administrators. On one hand, databases are designed to promote open and flexible access to data. But on the other side, it’s this same open access that makes your database vulnerable to many kinds of wicked activity. As the use of the Web grows on both Intranets and the public Internet, information security is becoming crucial to organizations. Now that it is extremely easy to distribute information, it is equally important to ensure that the information is only accessible to those who have the rights to use it. With many systems implementing dynamic creation of Web pages from a database, corporate information security is even more vital. Previously, strict database access or specialized client software was required to view the data. Now anyone with a Web browser can view data in a database that is not properly protected. Never before has information security been so vulnerable.

For much of Internet security, database specialists have had to rely on network administrators implementing precautions such as firewalls to protect local data. Because of the nature of Intranet/ Internet information access many security functions fall into a grey area of responsibility. This document I hope will describe areas where security falls within the domain of the DBA, who must create the information solutions.

New security procedures and technology are pioneered daily, so throughout this read I will be explaining various different database security systems that can be used to combat unwanted intruders.

There are three main areas to look at:

1. Server security -- ensuring security relating to the actual data or private HTML files stored on the server

2. User-authentication security -- ensuring login security that prevents unauthorized access to information

3. Session security -- ensuring that data is not intercepted as it is broadcast over the Internet or Intranet

These layers can be seen as layers of protection. For each layer of security added, the system becomes more protected. However, these layers can be broken if there is a weak link.

Server Security

Server security involves limiting access to data stored on the server. Although this field is primarily the responsibility of the network administrator, the process of publishing data to the Web often requires information systems specialists to take an active hand in installing and implementing the security policy.

The two primary methods in which information from databases is published to the Web are the use of static Web pages and active dynamic Web page creation. These two methods require almost completely different security mechanisms.

Static Web Pages

Static Web pages are simply HTML files stored on the server. Many database specialists consider static page creation the simplest and most flexible method of publishing data to the Web. In a nutshell, a client program is written to query data from a database and generate HTML pages that display this information.

When published as static Web pages, Web files can be uploaded to any server; for dynamic creation, however, the Web server usually must be modified.

The creation of the pages uses standard methods of database access control such as database security and login controls.

Once created, the files must be uploaded to the Web server. Protecting the documents stored there occurs in the same manner that any other Web documents would be secured. One of the most straightforward ways to protect sensitive HTML documents is to limit directory browsing. Most Web servers allow directories to be configured so that files stored within them may be read but the files may not be listed in the directory. This technique prevents any user who does not know the exact filename from accessing it. Access may be permitted by simply distributing the exact filenames to authorized personnel.

Dynamic Page Generation

Popular with large organizations, this method is gaining popularity as the technology to generate Web pages instantly from a database query becomes more robust. A dynamic Web page is stored on the Web server with no actual data but instead a template for the HTML code and a query. When a client accesses the page, the query is executed, and an HTML page containing the data is generated on the fly. The necessary data is filled into the slots defined in the template file in much the same way that a mail merge occurs in a word-processing program. A program might be active on the Web server to generate the necessary Web page, or a CGI script might dynamically create it.

One of the first security issues that a DBA must confront is setting up access to the database from the Web server. Whether using a CGI script, server-based middleware, or a query tool, the server itself must have access to the database.

Database Connections

With most of the dynamic connectors to databases, a connection with full access must be granted to the Web server because various queries will need to access different tables or views to construct the HTML from the query. The danger is obvious: A single data source on the server must be given broad access capabilities.

This makes server security crucial. For example, an ODBC data source given full administrator access could potentially be accessed by any other program on the server. A program could be designed to retrieve private information from a data source regardless of whether the program's author is permitted access. This security problem is most dangerous on a system where users are allowed to upload CGI scripts or programs to run on the server. To prevent unauthorized access to your data, make sure that the server that owns the database connector is physically secure and does not permit unrestricted program execution.

Table Access Control

Standard table access control, if featured in the user authentication system, it is more important on Web applications than on traditional client/server systems. DBAs are often slack in restricting access to particular tables because few users would know how to create a custom SQL query to retrieve data from the database. Most access to a database on a client/server system occurs through a specifically built client that limits access from there.

User-Authentication