SQL injection attacks have been a long-standing problem for web application developers. In this article, we will look at the meaning of SQL injection attacks, several factors that contribute to SQL injection vulnerabilities, and 8 successful ways that they can be prevented.
What is SQL Injection Attacks
SQL injection is a method of taking advantage of an improperly filtered user input to send commands directly to the database. When this occurs, the website operating in the backend becomes vulnerable to being compromised and consequently sensitive data such as usernames and passwords can be stolen.
One of the most common places where this problem is found is in web applications that were originally written with Microsoft SQL Server. Another instance where this issue can arise is when stored procedures are not properly filtered.
What factors contribute to SQL injection vulnerabilities?
There are several factors that contribute to the development of SQL injection vulnerabilities in web applications.
- Lack of an input validation mechanism
The most common cause for SQL injection issues is when the developer fails to filter user-submitted data. Whenever a piece of software accepts an external input such as from a user, website visitor, or another program it is important to validate the incoming data to ensure that it is of a correct format and can be accepted by the database. Failure to do so will result in SQL injection since, as we said above, some user input such as specific keywords or commands themselves (like Delete) will force the application to execute those statements within the backend database server.
- Database type
Another major cause for SQL injection vulnerabilities is that some databases have weaker security settings compared to others. For example, Microsoft SQL Server has a “DML” setting that allows the user to execute commands on a database without first specifying a command such as a SELECT or INSERT statement. This makes the product more vulnerable to attacks by an intruder since there is less security.
- SQL Server setting
The DML command in SQL Server, depending on the version of the product used, can also be filtered or blocked by adding an entry to the configuration file of the server. The danger is that this setting often remains unchecked and when it does not, there is a greater chance that an intruder will use the vulnerability to their advantage.
8 Successful Tips for Preventing SQL Injection Attacks
To prevent SQL injection vulnerabilities from being exploited, there are many steps that can be taken by the developer and administrator. They include;
1. Input validation
Input validation is a process that requires developers to filter any external input from being received by the software. In order to do this, it is necessary for the developer to know all of the different ways that data can be submitted and how those submissions should be handled. In most cases, special keywords such as “Delete” or “Insert” should be filtered or removed before they are processed by the backend database.
2. Stored Procedures should not be used
Stored procedures, a feature in most databases that allow a programmer to reuse code and save time when developing an application, often pose a security risk for SQL injection vulnerabilities. This is because developers make their own determinations about what the procedure should do and how it should operate without fully knowing if they are vulnerable to attacks. This can be circumvented by writing custom code that takes into account all of the factors that were discussed above.
3. Block URL Queries
One method of preventing SQL injection vulnerabilities is by blocking URLs in the database. This is done by adding certain parameters to the URL request. The problem with this method is that there are many legitimate reasons for a user to be making requests through URLs. For example, users are often asked to enter their username or password into a web browser address bar.
4. Use Prepared Statements
By using prepared statements, developers can prevent SQL injection issues by ensuring that the data is filtered before it can cause any damage. By enclosing user submitted strings in carefully constructed code, the developer can ensure that keywords or commands are replaced with safe values before they are provided to the database.
5. Check the Database for Vulnerability
More advanced forms of SQL injection can be prevented by checking the database behind an application to see if it is vulnerable. This is generally better than using stored procedures since it allows developers to factor out all of the possible vulnerabilities and create custom code that checks for those threats as well as others, such as directory traversal.
6. Use a Firewall
One of the best SQL injection prevention tools is an intrusion detection system or firewall that can monitor network traffic and establish what it considers to be dangerous web activity. In most cases, these systems will also work with databases so any web-based activity can be monitored in real-time.
7. Install Updates Regularly
By keeping the backend database up to date, developers can ensure that it is less likely to have known vulnerabilities or exploits that could be used against an application. This is especially important since the most successful SQL injection attacks are all based on using old techniques with newer systems. By consistently installing updates, administrators will reduce their chances of being compromised.
8. Backup & Maintain Data Regularly
The most basic of protection methods is to backup data on a regular basis. This will allow administrators to recover data in the event that it has been corrupted or lost during an attack. It can also be used to restore previous versions if needed, so business applications are not interrupted during repair efforts.
Conclusion
SQL injection is a common and relatively simple attack that can be used to steal or damage data in a database. By following these eight methods, it is possible to ensure that the risk of this occurring is significantly reduced, if not completely eliminated. This will help administrators to make sure their servers remain safe from malicious bot attacks while still allowing for developers to create applications that are as robust as possible.