Understanding, Exploitation, Risks, and Mitigations

SQL injection is a technique used by threat actors to trick a database server into an action that was not intended by the programmers who, in the event that SQL syntax is not somehow filtered out or blocked, may have inadvertently left their database vulnerable. By inputting SQL query information into a login box or appending it to a page action, the first sign of a server being vulnerable is an error being returned. The simple act of adding a single inverted comma into a search box may return an http 500 error, indicating a server problem. That is a green light for a SQL injection exploit.

The majority of websites today include some amount of dynamic content, as well as opportunities for visitors to log in and personalise their experience or complete financial transactions. Much of this functionality is supported by databases. A database with a connection to a webserver is, by definition, somewhat vulnerable to exploitation by a malicious actor. It is already only one hop away from directly connected. That means the data within it is vulnerable to exfiltration, which means the organisation is at risk of fines under data protection legislation, as well as the financial and reputational consequences associated with a publicised data breach.

How It Might Be Exploited

  1. Retrieving Data: Attackers can use SQL injection to access sensitive data such as usernames, passwords, and personal information by inserting malicious SQL code into input fields like login forms or search boxes.
  2. Bypassing Authentication: By manipulating the SQL query, attackers can bypass authentication mechanisms and gain unauthorized access to restricted areas of the application. For example, inserting ‘ OR ‘1’=’1′ into a login form can trick the system into granting access.
  3. Modifying Data: Attackers can change, delete, or insert data into the database, leading to data corruption or loss. For instance, an attacker can modify account balances or delete user accounts.
  4. Executing Remote Commands: In some cases, attackers can execute remote commands on the server, leading to a complete system compromise. This can be achieved by leveraging SQL injection to execute shell commands or other scripts.
  5. Denial of Service (DoS): Attackers can exploit SQL injection to cause a Denial of Service by running heavy SQL queries that exhaust server resources, making the application unresponsive.

Risks Associated with SQL Injection

  1. Data Breach: SQL injection can lead to unauthorized access and exfiltration of sensitive data, resulting in data breaches that compromise user privacy and trust.
  2. Reputation Damage: Organizations that fall victim to SQL injection attacks can suffer significant reputational damage, losing customer trust and confidence.
  3. Financial Loss: The cost of data breaches, legal penalties, and remediation efforts can result in substantial financial losses for organizations.
  4. Regulatory Non-Compliance: SQL injection attacks can lead to non-compliance with data protection regulations such as GDPR, resulting in fines and legal consequences.
  5. Operational Disruption: Unauthorized data modification or deletion can disrupt business operations, leading to downtime and loss of productivity.

The Exploit

By malforming SQL commands, such as this:

“ ‘ or 1=1 –hi

A SQL server vulnerable to injection will interpret the string as a successful login, because 1 always equals 1. This can result in the server dumping the whole user table to screen, providing a great deal of information to the malicious actor, and potentially providing access to the database immediately before them. Additional accesses may also be available as usernames are often consistent across networks, and users often use the same passwords for multiple systems.

Armed with a good knowledge of SQL query syntax, an attacker may be able to navigate their way through tables, exfiltrating all manner of sensitive data. The attacker may also be able to bypass authentication, providing access to data not originally intended to be available to the web server tier. The risks are not limited to exfiltration either, with the possibility a threat actor simply manipulates the data, compromising integrity, or stages a denial of service attack, impacting availability.

This vulnerability, now under the broader banner of ‘injection’ in the OWASP top-ten, has recently dropped down the rankings a little as a result of a comparatively simple resolution. The introduction of parameterised queries, or stored procedures in common terminology. Whilst restricting specific characters from inputs isn’t entirely without value, it is a great deal more work than configuring the system such that it accepts no external inputs whatsoever, and that any queries that are accepted by the system be executed via stored procedure only.

Other technical controls that are helpful in preventing SQL injection attacks include the use of web application firewalls, or WAFs, which can prevent malicious user inputs from being sent to the server, as well as regular penetration testing to ensure a robust security position. Regularly conduct security audits and penetration testing to identify and remediate SQL injection vulnerabilities. These proactive measures help ensure that security controls are effective and up-to-date.

To find out how I can help your organisation protect itself against a constantly evolving threat landscape, contact me via YDC. Read more about my testing services here.