Injection, the first on OWASP’s Top 10 list, is commonly found in database queries and OS commands, XML parsers, or when user input is sent as program arguments. OWASP is a non-profit organization that enhances the security of software and the internet.
What Are Injection Attacks
Injection attacks cover a wide range of attack methods. In an injection attack, an attacker provides a programme with untrusted input. An interpreter processes this input as part of a command or query. As a result, the program’s execution is altered.
Injections are amongst the oldest and most dangerous attacks geared toward web applications. These can lead to information stealing, data loss, loss of data integrity, denial of service, and full system compromise. The main reason for injection vulnerabilities is typically insufficient user input validation.
Injection attacks, particularly SQL Injections (SQLi attacks) and Cross-site Scripting (XSS), are not only destructive but also widespread, particularly in legacy applications. This attack type is considered a significant drawback in web security. It is listed as the number one web application security risk within the OWASP top and for a good reason.
Injection vulnerabilities are significantly dangerous because the attack surface is enormous (especially for XSS and SQL Injection vulnerabilities). Moreover, injection attacks are a well-understood vulnerability category. This suggests that several freely available and reliable tools enable even inexperienced attackers to abuse these vulnerabilities automatically.
Types of Injection Attacks
Databases back the overwhelming majority of web applications and most of the popular database management systems use SQL (Structured Query Language) as the data access language. A cybercriminal uses a SQL query (or another SQL statement) in the information entered into a web form, comment field, query string, or another input channel accessible to the user to perform a SQL injection attack.
If the target application is prone to SQL injection, it will send this information to the database. Rather than simply storing a comment or retrieving information, the database can execute SQL commands injected by the malicious actor. Even if the vulnerable application does not directly expose information, attackers might use blind SQL injection to indirectly reveal information from the database.
Types of SQL Injection
In-Band SQL Injection
The most basic type of SQL injection is in-band SQL injection. The attacker can use the same channel to inject malicious SQL code into the application and collect the results in this process.
Inferential SQL (Blind SQL )
Even if an attacker generates an error in the SQL query, the query’s response might not be transmitted to the web page. In such a case, the attacker needs to probe further.
In this type of SQL injection, the attacker sends numerous queries to the database to assess how the application analyses these responses. An inferential SQL injection is also as called Blind SQL injection.
Suppose an attacker cannot assemble the results of a SQL injection through a similar channel. Out-of-band SQL injection techniques could also be used as an alternate to inferential SQL injection techniques.
Typically, these techniques involve sending data from the database to a malicious location of the attacker’s selection. This method is highly dependent on the capabilities of the database management system too.
An out-of-band SQL injection attack uses your DBMS’s external file process capability. In MySQL, the LOAD_FILE () and INTO OUTFILE functions may be used to request MySQL to transmit the data to an external source.
Cross-Site Scripting (XSS)
Cross-Site Scripting (XSS) attacks are a sort of injection during which malicious scripts are injected into otherwise benign and trusted sites. XSS attacks occur when a malicious actor uses a web application to send malicious code, typically a browser side script, to a distinct user. Flaws that permit these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user among the output it generates without validating or encoding it.
An attacker will use XSS to send a malicious script to an unsuspecting user. The user’s browser cannot understand that the script should not be trusted and will execute the script. As a result, it thinks the script came from a trusted source. The malicious script will access any cookies, session tokens, or sensitive information maintained by the browser and use that website. These scripts can even rewrite the HTML page’s content.
OS Command Injection
Web applications generally ought to execute system commands within the underlying operating system. If the application contains command injection vulnerability, attackers will offer their operating system commands in user inputs. Successful command injection (also called shell injection) is extremely dangerous. It will permit the attacker to extract data regarding the underlying operating system and its configuration or maybe take complete control and execute arbitrary system commands.
Again, prevention is better than cure. Therefore it’s good practice to avoid calling system commands from web applications wherever possible. For cases wherever a system command is necessary, carefully validate user inputs and restrict them by whitelisting.
Code Injection (Remote Code Execution)
An oversized part of the application code is executed on the webserver for any web application. If the attacker is in a position to produce application code and obtain the server to execute it, the application has code injection vulnerability. For instance, if the application is written in PHP, the attacker will inject PHP code which the PHP interpreter then executes on the server. This is called an Eval injection attack.
Note that code injection is completely different from OS command injection. However, if the interpreter permits system function calls, application code may be injected that executes a system command (effectively achieving OS command injection). If the attacker manages to induce remote code execution, the target system should be considered compromised, which is a critical vulnerability.
The final type of injection vulnerability during this compilation is XML external entity (XXE) injection. By exploiting support for legacy document type definitions (DTDs) combined with weak XML program security, attackers will use specially crafted XML documents to perform a spread of attacks, from path traversal to server-side request forgery (SSRF) and remote code execution.
Unlike the previous four attacks, this one doesn’t exploit unvalidated user input. Instead, it targets inherently unsafe legacy functionality in XML parsers. Therefore it is notably dangerous if your application processes XML documents. The only way to avoid this vulnerability is to utterly disable support for DTDs, or at the very least for external entities.
A CCS injection exploits a vulnerability found within the ChangeCipherSpec processing in some versions of OpenSSL.
During such an attack, attackers send invalid signals during the connection session between servers and clients.. This permits them to seize encryption key materials, access the communication between server and client, and probably perform theft.
These are the foremost common and critical injection attacks used on internet applications. Unfortunately, protecting your applications can be an uphill task for companies or people with several internet applications and limited developer time and resources.
How to detect injection vulnerabilities
The easiest way to detect injection vulnerability is by using an automated web vulnerability scanner. Like an automated pentest tool, such a scanner can easily detect attack vectors and help you take the necessary steps to protect your application. Now that you understand the most common web application vulnerabilities make sure you cover the basics and account for these common injection attacks in your development method.
How do we prevent injections attacks?
In order to protect your web application from injection attacks, you must code it securely. These are some of them:
- Penetration Testing
- Using ready statements with parameterized queries that distinguish between code and user input and do not mistake statements for commands
- Using stored procedures that are outlined and stored within the database and called from the web application
- Limiting special characters to command string concatenation
- Escaping all user-supplied input (the last measure, according to OWASP)
- Reducing your application’s attack surface by removing any unnecessary functionality that will otherwise need to be guarded
- Enforcing the least privilege and strict access by permitting only those privileges that are necessary for an account