A Structured Query Language (SQL) injection is a cybersecurity attack technique or vulnerability where malicious variants of SQL statements are placed inside entry fields of backend databases, either deliberately or inadvertently, which facilitates attacks on data-driven applications. This article explains the meaning of SQL injections, their various types, examples of attacks, and best practices to protect against SQL injections.
Table of Contents
What Is SQL Injection?
A structured query language (SQL) injection is defined as a cybersecurity attack technique or vulnerability, where malicious types of SQL statements are placed inside entry fields in backend databases, either deliberately or inadvertently, which facilitates attacks on data-driven applications.
How a SQL Injection Functions
SQL injection (often referred to as SQLi) is a commonly used attack vector in which a malicious SQL script is utilized to manipulate back-end databases to obtain data that was not meant to be exposed. This data could include sensitive corporate data, subscriber lists, or confidential consumer information, among other things. SQL injection has a wide-ranging impact on a company’s operations. For example, it may result in the assailant reading illegal user lists, deleting entire columns, and, in some situations, gaining admin access to a database, which are all extremely damaging to a corporation.
When estimating the cost quotient of an SQL injection, keep in mind the loss of consumer trust if private details such as contact information, locations, and credit card data are stolen. While this technique can assault any SQL record, the most common target is data-heavy web pages connected to a backend database.
Types of SQL Injections
SQL injections can be classified based on how they access underlying data and the amount of harm they can cause. Inferential SQL injection (blind), in-band SQL injection (classic), and out-of-band SQL injection are the three most common types of SQL injections.Â
- In-band SQL injection: The attacker exploits the same line of communication to execute assaults and acquire information. Because of its simplicity and speed, in-band SQL injection is a very common type of SQL injection attack. This approach is divided into two sub-variations:
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- Error-based SQL injection: The attacker causes the database to emit error messages by performing activities. The attacker could use the evidence given by these error codes to obtain knowledge about the database’s architecture.
- UNION-based SQL injection: This approach uses the UNION SQL function, which combines numerous database select queries into a single hypertext transfer protocol (HTTP) server. This reply may contain information that the intruder can use.
- Inferential (blind) SQL injection: To understand the server’s architecture, the attacker delivers information payloads to it and watches how it responds and behaves. Since no data is communicated from the server database to the assailant, this method is known as blind SQL injection. As a result, the attacker cannot display information regarding the attack in-band. Blind SQL injections depend on the server’s reaction and behavior patterns; therefore, they are usually slower to perform but just as dangerous. The following are the two types of inferential SQL injections:
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- Boolean: The attacker issues a SQL request to the database, requesting a response from the application. The response will differ based on whether the question is true or false. The content in the HTTP response will alter or remain unchanged depending on the outcome. The intruder can then determine if the message produced a true or false answer.
- Time-based: The attacker issues a SQL request to the database, causing it to wait (for a set number of seconds) before responding. The attacker can tell if a search is true or false by how long it takes the system to answer. An HTTP answer will be produced depending on the outcomes, either immediately or after a delay. Without relying on database information, the attacker can determine if the communication they used responded true or false.
- Out-of-band SQL injection: This type of attack is only possible if certain functionalities on the computer system used by the web-based application are available. This type of attack is typically employed to complement in-band and inferential SQL injection attacks.
Out-of-band SQL injection is used when an intruder cannot launch an assault and collect information over the same route or when a site is too slow or unreliable to complete these activities. These methods rely on the server’s ability to send domain name system (DNS) or HTTP queries to send data to an assailant.
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SQL Injection Cheatsheet
According to the Open Online Application Security Project (OWASP), SQL injections are by far the most commonly discovered vulnerability in web apps. SQL injection is a web application assault that may be used on Android and iOS apps and any other software that employs SQL databases for information storage.
An SQL injection cheat sheet document contains detailed technical data about the various types of SQL Injection vulnerabilities. It is helpful for both experienced penetration testers and those just starting in web application security. Some of the key components in a SQL injection cheat sheet include:Â
- String concatenation and substring rules
- Commenting guidelines for systems like Oracle, Microsoft, PostgreSQL, and MySQL
- Queries to fetch the database version and database contents
- Syntax to trigger conditional errors and time delays
- Rules to run a DNS lookup with data exfiltration and batched queries
It is possible to access cheat sheets on various database systems, which makes it easier for ethical hackers and penetration testers to simulate SQL injection attack events. Keep in mind that threat actors may also use these cheat sheets for unethical purposes.Â
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Examples of SQL Injection Attacks
An attacker who wants to execute SQL injection uses a common SQL query to target database entry vulnerabilities. This assault vector can be used in various ways:
Examples of SQL Injection Attacks
1. Accellion attack
Accellion is the creator of the File Transfer Appliance (FTA), a network node designed to transport large volumes of sensitive information widely utilized in enterprises around the globe. It is over 20-years old and has reached the end of its shelf life. Since January 2021, the company has acknowledged and started addressing the effects of a long-standing SQL injection vulnerability.Â
FTA was the target of a one-of-a-kind, complex assault that combined SQL injection with executing code on the operating system. Experts believe the Accellion attack was made out by hackers linked to the FIN11 financial fraud group and the Clop ransomware outfit. SQL injection isn’t simply an assault that affects online apps or web applications; it can also be employed to attack back-end systems and steal information, as demonstrated by this example.
Accellion was a supply chain attack that has impacted several companies that have used the FTA device. The State of Washington, the Reserve Bank of New Zealand, Investments Commission, the Australian Securities, telecommunications giant Singtel, and safety software firm Qualys were among the targeted organizations.Â
2. Epic Games attack
In 2016, Epic Games issued a security alert to 800,000 users whose accounts are connected to the firm’s internet forums. Several of the game designer’s forums were temporarily locked down. Consumers were encouraged to reset passwords on any sites with duplicate keys for any of their forums. Epic Games stated the theft was linked to the Unreal Engine and Unreal Tournament forums, with email addresses plus forum-related information among the stolen data.Â
Epic Games also announced a more severe hack affecting Infinity Blade, UDK, earlier Unreal League games, and Gears of War game communities. Attackers acquired access to email accounts, salted hashed credentials, and other information associated with the forums.
3. Kaseya attack
Kaseya, an IT consulting firm, was hit by ransomware in July 2021, putting thousands of consumers of their managed service provider clients at risk. According to the company, cyber attackers were able to attack weaknesses in Kaseya’s VSA product to bypass authentication and execute arbitrary commands through an SQL injection. An outfit called REvil was used through the VSA product’s regular functionalities to deploy ransomware to consumer endpoints. Over 36,000 managed service providers could not access Kaseya’s flagship VSA service for at least four days.Â
4. Potential WooCommerce attack
In July 2021, WooCommerce announced that several of its software versions and feature plug-ins were vulnerable to SQL injections, and cybersecurity analysts noted several attacks occurring during that time. These breaches may have occurred as a result of WooCommerce’s unpatched vulnerabilities. These can be a flaw in the WooCommerce checkout payment processing plugin, cross-site scripting (XSS) weakness in the shop plugin that permits slight infiltration of arbitrary web content, or a design error in the WordPress approval system used by plugins.
When it comes to hijacking WordPress and WooCommerce sites, scammers employ a variety of inventive and illegal tactics. Although no apparent symptoms have shown that a website has been hacked, looking for some of the most typical WordPress security indicators can aid this. Some of the most prevalent warning indicators are:
- Site redirection to an unauthorized URLÂ
- Inappropriate content on the homepage of the websiteÂ
- Limited access to the WordPress admin areaÂ
- An odd drop in trafficÂ
- An alert in search results saying “This Page May Be Compromisedâ€
- Browser issues, indicative of an attackÂ
- An unusual surge in website registration
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Preventing SQL Injection: Top Best Practices for 2022
Although SQL injection assaults remain the most significant threat to web admins, they can reduce the risk by taking the right measures. Here are some actions that you can take to lessen your chances of being a victim of a SQL injection:
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Best Practices to Prevent SQL Injection
1. Verify user inputs
Verifying user inputs is a frequently used initial measure to minimize the chances of SQL injection. First, one must determine the most critical SQL statements and then create an allowlist for all acceptable SQL statements, leaving out any accounts that have not been validated. Data integrity, or query modification, is the term for this process.
Furthermore, one should configure user data entries as per the context. For instance, email address entry fields can be limited to only accept character inputs found in email addresses, including the compulsory “@†symbol. Social security numbers and telephone numbers should only be limited to enable the specific set of numbers for each. While this action will not protect from SQL injection hackers by itself, it will provide a layer of safeguards to the typical data-gathering methods used in SQL injection attacks.
2. Limit the use of special characters in data
Insufficient data cleaning is another factor to consider while defending against data breaches. Cleaning data to stop string compounding is crucial since SQL injection criminals can leverage unique character patterns to attack a database.
Configuring inputs to a program like MySQL’s real escape string () is one approach to accomplish this. This prevents any potentially harmful characters (for example, a single quote symbol) from being sent to a SQL statement as commands. Prepared statements are one of the most common ways to avoid unverified queries.
3. Enforce prepared statements and parameterizations
Unfortunately, input validation and information sanitization are not one-size-fits-all solutions. Businesses must employ prepared statements with parameterized queries for all SQL statements, sometimes called variable binding. You can differentiate between user intervention and code by declaring all SQL code associated with requests or parameterization.
Keep in mind that although flexible SQL as a coding style can provide more flexibility in app development, this can result in SQL injection vulnerabilities being accepted as valid code commands. This is because the server will consider harmful SQL queries as data rather than potential commands by using conventional SQL.
4. Make use of stored procedures in the database
Employing stored procedures necessitates variable binding in the same way that parameterization does. Stored procedures are saved in the database and invoked from the web app. However, remember that stored procedures may also be susceptible to security flaws if dynamic SQL creation is employed. According to organizations such as OWASP, one or the other parameterized ways is required, but neither strategy is sufficient for good security.Â
5. Actively manage patches and updates
SQL injection flaws in databases and programs are constantly discovered and disclosed publicly. As with many other concerns associated with cybersecurity, businesses must stay up-to-date on the news and implement upgrades and fixes quickly. This includes keeping all online application software aspects, such as database server programs, frameworks, libraries, connectors, and web server software up to date for SQL injection reasons.
See More: What Is a Security Vulnerability? Definition, Types, and Best Practices for Prevention
6. Implement a web application firewall
It is strongly advisable to use an appliance or software-based web application firewall (WAF) to filter out harmful material. Today’s firewalls, notably next-generation firewall (NGFW) and firewall as a service (FWaaS) options come with a robust set of specific provisions as well as the flexibility to adjust configurations as required. WAFs come in handy for SQL injection prevention when a patch or update is not yet available.
A prominent example is ModSecurity, a free, open-source component for Apache, Microsoft IIS, and Nginx web servers. ModSecurity has a complex and ever-changing set of rules for filtering potentially hazardous web requests. Its SQL injection safeguards detect many attempts to smuggle SQL across web channels.
7. Harden your operating system and applications
This best practice ensures that your end-to-end physical and virtual IT infrastructure works deliberately and prevents SQL injection threats. With the recent revelation of supply-chain hacks in 2020, many developers are turning to industry-standard safety mechanisms such as the National Institute of Standards and Technology (NIST) frameworks and others to harden their apps and operating systems. Security standards by application providers can also assist organizations in improving their defensive posture by identifying and disabling unneeded applications and infrastructure.
8. Limit the area of attack
The multitude of possible entrances for attackers is referred to as an attack surface in cybercrime. In the case of SQL injection assaults, it covers either further securing or discarding database features that are not required.Â
The expanded stored procedure xp_cmdshell in Microsoft SQL Server is one example. This technique can open a command prompt in Windows and execute a string. The intruder can wreak significant damage since the xp_cmdshell-generated Windows program has the same protection privileges as the SQL server service account.
9. Create appropriate privileges and control access
Given the importance of a SQL database to a business, one must enforce zero-trust and least-privilege access requirements. For instance, there is no reason for a webpage to have extra INSERT, UPDATE, or DELETE access if it only requires the use of SELECT queries for a database. Setting read access to the network is also key to the notion of least privilege for SQL injection prevention.Â
Furthermore, you should only provide individuals access to your database if necessary. Using a controlled access profile for general purposes is safer, and it also limits an assailant’s access if the less-privileged identity is compromised.
See More: Top 10 Vulnerability Management Tools for 2021
Takeaways
An SQL query is simply a request submitted to a database, a digital store of information — for some activity or purpose to be executed, such as data querying or SQL code execution. For instance, when a person’s login credentials are submitted using a web form to access the website, it is an example of an SQL query. This form field is typically meant to accept information such as names or passwords.Â
However, since most web applications have no way of preventing more content from being submitted, security risks might develop. Hackers can utilize this flaw by using the style’s input fields to submit their queries to the server. This could enable them to engage in various malicious behaviors, such as stealing personal information or changing data in the database for their own gain.Â
In the age of data proliferation, nearly every app and online service is connected to a database that an SQL injection could potentially infiltrate. Reconfiguring access privileges, enforcing network security measures, and educating application users are critical to maintaining a safe digital landscape.Â
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