What is SQL Injection? Understanding SQLi Attacks

Definition may only vary amongst professionals. But one thing about SQL Injection remains constant. It is typically a programming language that cybercriminals are using to issue illegal database commands on our databases to hack and tamper with, or steal the information.

With proper SQL command execution on one’s computer, a criminal can spoof identities, and make themselves admins. With this privilege, they can effortlessly tamper with existing data, retrieve or wipe out system data, modify transactions or balances, conduct any other manipulating behaviours imaginable.

__Before, however, we delve deeper into more technical details on SQL Injection, we think that it’s in your best interest to first understand what SQL Injection means from an elementary point of view. __

What is a SQL Injection?

From an elementary angle, structured query language (SQLi) is a computer programming language that is used to manage databases.

And according to Microsoft, in today’s cybercrime world, SQL Injection is an attack whereby hackers insert malicious codes into strings which are then passed to an instance of SQL servers for undertaking. It is a method people use to exploit user data through a web page input. And this is done by Injecting SQL commands as statements.

Therefore, it’s strongly recommended that any processes that construct SQL statements be reviewed for an Injection exposure. This is because an SQL server will often only enforce all semantic valid queries that are received. But it helps to also know that even the parameterized data can be manipulated by highly skilled and determined hackers who know what they are doing.

SQL Injection Examples

There are many different types of SQL Injection techniques that cybercriminals can employ to access and manipulate user data. One of the following examples is what a black hat hacker would likely use.

Examples of SQL Injection

  1. Examine System Databases. With this procedure, cybercriminals need to acquire more information regarding their victim’s database. Once they have substantial info, they can access your database and steal any info, or launch other phishing attacks.

Generally, through this SQL Injection attack, a criminal can get info regarding the database column, and fetch info from several database tables.

  1. Retrieve Hidden Information. This speaks more about the kind of things people do with the internet that they are often not expecting that someone else would learn about them.

Through this procedure, the hacker can access information which, maybe, the site owner didn’t want to share with others yet. The following example might paint a clear picture of this point. Picture when someone visits a website or an eStore to purchase a product.

Usually, different things are listed or displayed on the page. But in this very same page, a hacker can issue a command to ask the same site to give them more info about other products which are clearly not included in it, and they get it.

  1. Subvert Program Logic. Picture a situation where a program or app that allows for username and password logins, but within the same program, a cybercriminal can tamper with the logic in a way if they enter their username and password, it allows them to sign in through the SQL comment sequence!

Thing is, this kind of SQL Injection attack allows the criminal to tamper with the purpose of a program and change their desired target to achieve their desired purposes.

  1. SQL Injection Blind Vulnerabilities. This method of SQL Injection bypass login and allows criminals access to obtain information illegally. Let me explain.

Technically, they call it SQL Injection blind because no data is returned in this procedure. Therefore, this method technically allows the hacker to issue a new command, or in other words, inject a new request into the target website, and access any data they want.

Moreover, this method also allows the criminal to observe the time in which the information cycle takes. The criminal can then use such time results to check accuracy or correctness of a process.

  1. Out-of-Band SQL Injection. Out-of-band SQULi procedure is a special case by itself. This method only works if specific database server features that are used by certain software are turned on. This scheme is often considered as the alternative to in-band SQLi which we are going to cover next.

Further, instead of relying on the hacker querying the database to examine HTTP responses or error messages, Out-of-band SQLi expects the server to create HTTP or DNS (Domain Name System) requests in order for the criminal to obtain info such as passwords, and usernames.

  1. In-Band SQL Injection. This is an ordinary kind of SQLi attack known for its clearness and efficiency. The method involves 2 variations: union-based SQLi and error-based SQLi. here’s a glimpse at these 2 variations:
  • Union-Based SQL Injection. In this case, a hacker uses the database Union SQL operator to return a single HTTP reaction. They can then evaluate the response for clues regarding contents of the specific database.

  • Error-Based SQL Injection. In this scenario, a hacker injects SQL queries and hopes that the database will return an error message. Such error messages provide clues or give the hacker important information regarding the database and its structure.

SQL Injection Prevention

SQL Injections are amongst the top most used web attack vectors that are often used with the aim of retrieving important data from organisations, or individual networks. Whenever you hear about stolen credentials; think passwords, credit cards, billing info, hospital records, or anything else that we don’t often want to share with others; it is often done via SQL Injection exposures.

Accordingly, while this info may almost only appear as very technical for the average user, professional developers know that since the user input channels are often the key vectors for such attacks, an effective approach is to control and vett user inputs to observe attack patterns. But it’s still possible for developers to avoid vulnerabilities by employing the below key prevention methods.

  • Parameterized queries
  • Stored procedures
  • Input validation
  • Escaping
  • Avoiding admin privileges

1. Parameterized Queries

These queries are a means of pre-compiling SQL statements to distribute parameters so that a statement can be enforced. This scheme makes it possible for databases to identify the code, and determine it from input data.

Further, this coding method will help you mitigate SQL Injection attacks because user input is systematically quoted, and the supplied input won’t cause the shift of the purpose.

Moreover, although PHP 5.1 offered a much better approach while working with databases, you can still use parameterized queries with MySQL extension. However, PHP Data Objects (PDO) obtains procedures which simplify the usage of parameterized queries. And because PDO runs on vast databases, not on MySQL only, it makes the codes more compact, and easier to read.

2. Stored Procedures

Stored Procedure, or simply SP procedure, requires a developer to group one or multiple SQL statements into logical units to define an action, or execute a plan. Besides, subsequent executions enable statements to be parameterized.

In a nutshell, this code is the kind that can be stored for later; and it can be used several times. Equally, it means that whenever you will want to use the same kind of query in future, you will need to just call the stored procedure instead of writing a new one.

3. Input Validation

This scheme is more targeted at verifying whether or not the kind of inputs that users are submitting are permitted. Likewise, it also ensures that it is the only accepted format, type, length, etc. and that only those values that successfully complete Input Validation are allowed to process. Further, this assists on neutralising commands that criminals inject into the input strings. Think of it as a way to see who’s knocking before you let them in.

Nevertheless, validations are not only meant for applying to areas where users are allowed to put in inputs. This means that you must also take care of these predicaments in equal measures.

  • Utilise ordinary expressions like whitelists for structured info. For instance, you can use: zip code, name, age, survey response, income, etc. to assure powerful input validation.
  • If there is a fixed set of values like radio button or drop-down lists, for example, you can assume the value that is returned. This input data should exactly match one of the provided choices.

4. Escaping

Always ensure to utilise character-escaping protocols for user supplied inputs that are almost often provided by every DBMS (database management system). This is performed to ensure that DBMS doesn’t confuse it with the developer’s SQL statement. For instance, you can use mysql_real_escape_string() in PHP to deflect the characters which might lead to involuntary SQL commands. For those who understand, the below example might paint a picture of a scenario of a modified version of login bypass, or rather an SQL Injection bypass login.

Example of a Modified Login Bypass $db_connection = mysql_connect(“localhost”, “user”, “password”, “db”); $username = mysql_real_escape_string($db_connection, $_POST[‘username’]); $password = mysql_real_escape_string($db_connection, $_POST[‘password’]); $query = “SELECT * FROM user WHERE username = ′″ . $username . ″′ AND password ′″ . $password . ″′″;

Previously, a code would be vulnerable to involving a ( \ ) escape character in front of the single quotes. Having this tiny alteration, however, will protect you against illegitimate users, and prevent SQL Injections.

5. Avoiding Admin Privileges

Avoid integrating or connecting software to the database with an admin account, unless it’s primarily needed. Doing so prevents or restricts a determined hacker from accessing the entire system.

Equally, a non-admin account server can still pose risks on software—and even more so if, say, a database is utilised by several apps, and databases. For such reasons, it is, therefore, critical or, let’s just say, better to reduce or enforce less privileges on databases to protect apps against SQL, or other code injections.

Tip. Always make sure that every software has their own database certificates, and that these credentials contain the minimum rights that such programs need.

Also, you should focus more on identifying which permission rights a software needs, instead of only trying to figure out the kind of access rights to remove. For instance, if, say, someone needs access to only a few parts…, you could establish an aspect that only serves this function.

Web Application Firewall

Having a web application firewall (WAF) is one of the best practices or ways of identifying SQLi attacks. Having a WAF running in front of web servers will monitor all traffic flows of a web server, and recognise patterns that form a threat.

Basically, having a WAF running in front of your web server is like putting a barrier between the net, and your web applications. Let me explain.

A web application firewall runs through specified customisable internet security rules. As a result, these sets of actions notify the WAF about the defenselessness, and traffic behaviour that should be scanned. Based on that data, the firewall will keep observing that application or program, as well as the GET and POST requests that program is obtaining so it can specify, and block unwanted traffic.

Moreover, WAFs offers yielding protection against various malicious attacks including SQL Injection, Session hijacking, Cookie poisoning, Cross-site scripting (XSS), Parameter tampering, to name a few.

Also, considering the rewards of having Guardio, for instance, running in front of your web server, the program also goes beyond parenting from Injection attacks. As such, it should often be assumed as part of internet security defence in-depth protocol.

Frequently Asked Questions (FAQs)

1. What’s the Difference Between SQL and XSS Technically, the main difference between these two is that XSS is a type of system exposure that only injects malicious codes to a web page. As a result, a malicious code can, therefore, run in the users on that network, from within the browser. Meanwhile, SQL Injection is a site hacking scheme that adds SQL codes to a web form input box to obtain illegal access to resources and tamper with existing data.

Accordingly, every company maintains their sites, which often helps in enhancing business profitability. Moreover, a web software often contains a server side, and the client side. While the server side includes the database, the client side includes the user interface (UI) for users to interact with a program.

2. Is SQL Injection Illegal? In a nutshell, SQL Injection is legal until it’s not. Well, it depends on the scenario. Essentially, if anyone gains unauthorised access to your sensitive information; this is deemed illegal, and is greatly punishable.

Also, if, say, a black hat hacker attacks your database and succeeds—they can compromise system security, access any information within that system, including those in devices that share the same network, steal your identity or commit other system or data manipulation activities.

Normally, there are various threats affecting the proper functionality of a program; two of which are very common (XSS and SQLi).

3. Does SQL Still Work in 2022? SQL has been there for nearly four decades. It is still in demand and chances are, SQL will keep existing for many years to come because it’s a very powerful tool for vast business sectors.

Also, Microsoft SQL Server 2022 which is due to be released later this year was announced in November 2021. This announcement, of course, broke the long silence regarding the next SQL server version, and answers the question more accurately.

4. How is SQL Injection Done? A hacker would first search for SQLi vulnerable sites using various tools like Haviv Pro, Google Dorks, etc. that are focused on dynamic files .asp or .php followed by parameters attributes such as these examples; ?id=, ?category=, ?decl_id=, and so on.

Moreover, you can paste or retype this example: inurl:/articles.php?id= in the Google search panel and push enter to search for Google Dorks. Criminals will often visit the site URLs that appear on such search results to find vulnerable sites.

Once a hacker has located a potentially exposed site from the Google Dorks list, they will often utilise a code Injection or SQL Injection procedure to gather more info about that specific site.

5. Why Should a Hacker Use SQL Injection? Those who are familiar with hackers know that these highly skilled tech geeks will almost stop at nothing if they want to breach an application, or system database to extract useful info. SQL Injection is a common technique, and highly effective in data breaching that hackers often use to achieve their end.

Amongst the most common types of hacking tactics, attacking websites is on top of the list. Cybercriminals use different existing tools to examine system or network vulnerabilities and existing coding problems. They then attack the system’s security by using one of SQL Injection schemes to gain illegal access to that system/network.

6. What Causes SQL Injection? It is not in our nature to intentionally leave behind traces of security holes which can later be exploited with structured query language (SQLi). There are a dozen reasons why these security holes come about. But oftentimes, it is not because someone wrote bad code. Here are 2 common causes of SQL Injection.

  • Unpatched or outdated applications. Using legacy software, or unsupported app versions or features, can introduce security holes which may not be patched, or recognised as fast as they would by a new version of the program.

Tip. Running patched and latest software versions is crucial to preventing vast security exploits—including SQL Injection attacks. Also, if you keep monitoring new security weaknesses, and act accordingly and as required, you’re sure to curb unnecessary surprises.

  • Legacy or old code. A code may have been adequate or secure enough when it was written a few decades ago. Problem is, what might have been secure in yesterday’s tech world might not be accepted in today’s advanced technology.

Tip. When creating new features, and or writing the new codes, it’s essential to review the old ones to make sure that the old things are not also becoming antiquated.

Also, such codes that are no longer needed, or used should be removed. Because they’re the most likely to be forgotten in future. And this balance will only help you ensure that all codes remain relevant and secure when faced with the test of time.

7. What is SQL Injection Example? There are vast SQL Injection examples. Some of which include:

  • Examining the system database. This is a process of examining a victim’s database to gather sufficient info to gain unauthorised access”.
  • Retrieving hidden information. This is when people can inject codes that allow them to get info about products which are not listed on a specific page that everyone else can’t see.
  • Subverting system logic. Hackers can manipulate vast software programs that need username and password to authenticate. They can use their own to allow them to sign in through the SQL comment sequence.
  • Blind SQL Injection susceptibilities. This one was named blind SQL because no data is returned.

8. What’s a compound SQL Injection? To circumvent certain security measures, smart hackers will sometimes apply multi-vector attacks against their victim’s site. While one single attack can be mitigated, it can as well become the main focus of attention for the information security teams or the site’s database admins.

Moreover, DNS hijacking and DDoS attacks among other dozen methods of disruptions are also utilised as a means of destruction sometimes to implement SQLi attacks.

Therefore, a more comprehensive strategy for threat mitigation will provide a wide range of protection against injection attacks. Security tools like Guardio, DNS security, DDoS mitigation, and Cloudflare web application firewalls, for example, comprise core elements of a more holistic strategy.

In Summary

Most security vulnerabilities are identified, patched, and extinguished for good. Some, however, still linger on and continue to plague program development and will continue doing so for many years from now.

Putting aside social engineering and other non-technical attacks—SQL Injection is often misunderstood yet it continues to be among the top security threats to our data. However, there are certain measures that can still be implemented to mitigate these security threats. And as technology advances, these threats also increase and so are the ways to mitigate these threats.

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