SQL Injection

KZero Staff
Oct 19, 2023

SQL injection refers to the exploitation of a vulnerability in relational databases that use SQL language for data insertion. With a SQL injection, a hacker takes advantage of user inputs in the database that are not indexed correctly and of metacharacters such as double dashes, quotation marks, quoted elements, and semicolons. These characters, in fact, have special functions for the SQL interpreter and allow for external modification of the executed commands. SQL injection often occurs with PHP and ASP programs that have old interfaces. In fact, the inputs are sometimes not filtered in the right way and end up being the perfect target for a hacker attack.

With the targeted use of function characters, an unauthorized user can inject other SQL commands and manipulate records so that these can be changed, read, or deleted. In the most critical instances, it is even possible for the hacker to gain access to the system command line and thus access the entire database server by exploiting this method.

In theory, every website and web application is at risk of being a target of an SQL injection—that is, as long as SQL is the language used for the database. Very often the developers of the programs that communicate with the database do not take sufficient care of the security aspect and make it vulnerable to SQL injection attacks. We know that discovered vulnerabilities do not remain secret for a long time on the internet. There are pages that inform us about current vulnerabilities and also reveal to cyber criminals how they can find sites affected by these vulnerabilities.

Among the most common examples of SQL injection attacks are:

  • Retrieving hidden data: The SQL query here is modified to return additional results.
  • Subverting application logic: The query is changed in order to interfere with the logic of the application.
  • UNION attacks: In this instance, the data is retrieved from different database tables using multiple queries and the results are combined.
  • Denial-of-service attacks: The database server is overloaded with queries so that the normal requests and queries are not processed within a reasonable time.
KZero Staff

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