Top 10 OWASP vulnerabilities for 2023 | Every Pentester Should Know

The Open Web Application Security Project (OWASP) is a nonprofit organization dedicated to improving the security of software. Every few years, they release a list of the top 10 web application security risks based on input from security experts around the world.

Here are the top 10 OWASP vulnerabilities for 2023:

Injection flaws: Injection flaws occur when untrusted data is sent to an interpreter as part of a command or query. Attackers can use injection flaws to bypass authentication, execute unauthorized commands, or read sensitive data. Examples of injection flaws include SQL injection, XML injection, and command injection.

Broken authentication and session management: These vulnerabilities occur when authentication and session management functions are not implemented correctly. Attackers can use these vulnerabilities to hijack user accounts, bypass authentication, and perform unauthorized actions. Examples of broken authentication and session management vulnerabilities include session fixation attacks and weak password storage.

Cross-site scripting (XSS): XSS vulnerabilities occur when web applications don't properly validate user input and output. Attackers can use XSS attacks to inject malicious code into a web page, steal user credentials, and perform other unauthorized actions.

Broken access controls: Broken access controls occur when web applications don't properly enforce access controls, allowing attackers to perform actions they shouldn't be able to. Attackers can use broken access controls to read or modify data they shouldn't be able to access, or to perform unauthorized actions.

Security misconfigurations: Security misconfigurations occur when web applications are configured incorrectly, leaving them vulnerable to attack. Examples of security misconfigurations include leaving default passwords in place, not properly securing servers, and not updating software to the latest version.

Insecure cryptographic storage: Insecure cryptographic storage occurs when sensitive data is not encrypted properly, allowing attackers to read or modify the data. Examples of insecure cryptographic storage include storing passwords in plain text, using weak encryption algorithms, and not properly protecting encryption keys.

Insufficient logging and monitoring: Insufficient logging and monitoring can make it difficult to detect and respond to security incidents. Attackers can use this vulnerability to cover their tracks and evade detection.

Insecure communication: Insecure communication occurs when web applications transmit sensitive data over unencrypted channels, allowing attackers to intercept the data. Examples of insecure communication include using HTTP instead of HTTPS, not validating SSL/TLS certificates properly, and not encrypting data sent to mobile devices.

Using components with known vulnerabilities: Using components with known vulnerabilities occurs when web applications use outdated or insecure third-party components, leaving them vulnerable to attack. Examples of components with known vulnerabilities include using outdated libraries, not properly patching software, and not properly vetting third-party software.

Server-side request forgery (SSRF): SSRF vulnerabilities occur when web applications allow attackers to send requests from the server to other systems, bypassing firewalls and other security controls. Attackers can use SSRF to steal data, perform unauthorized actions, and execute code on other systems.

 For example, a SQL injection attack is a type of injection flaw in which an attacker injects malicious SQL commands into a web application's input fields. If the web application does not properly validate and sanitize the input, the attacker can execute their malicious commands, potentially allowing them to extract sensitive data from the application's database or even modify or delete data. Here is an example of a SQL injection attack:

Suppose a web application has a login page that takes a username and password as input. The application uses the following SQL query to check whether the username and password are valid:

sql
SELECT * FROM users WHERE username = '$username' AND password = '$password'

An attacker could enter the following input into the username field:

vbnet
' OR 1=1--

This input would cause the SQL query to be executed as follows:

sql
SELECT * FROM users WHERE username = '' OR 1=1--' AND password = '$password'

The double dash at the end of the input is a comment symbol in SQL, so everything after that is ignored by the database. The OR 1=1 condition always evaluates to true, so the query returns all users in the database, regardless of their password. The attacker can then log in as any user they choose.

Another example of a vulnerability is cross-site scripting (XSS), which occurs when an attacker is able to inject malicious code into a web page, potentially allowing them to steal user credentials or perform other unauthorized actions. Here is an example of an XSS attack:

Suppose a web application allows users to post comments on a forum. The application does not properly validate or sanitize the comments, so an attacker is able to post a comment with the following text:

php
<script> alert('You have been hacked!'); </script>

When other users view the forum page, the script will execute in their browser, displaying a pop-up message that says "You have been hacked!" This is a relatively benign example, but an attacker could use XSS to steal user credentials or perform other malicious actions.