What are Basic Web Application Attacks?

May 21, 2026

Cybersecurity might as well have its own language. There are so many acronyms, terms, sayings that cybersecurity professionals and threat actors both use that unless you are deeply knowledgeable, have experience in the security field or have a keen interest, one may not know. Understanding what these acronyms and terms mean is the first step to developing a thorough understanding of cybersecurity and in turn better protecting yourself, clients, and employees.

In this blog series, we aim to explain and simplify some of the most commonly used terms. Previously, we have covered bullet proof hosting, CVEs, APIs, brute force attacks, zero-day exploits, doxing, data harvesting, IoCs, credential stuffing, ransomware as a service, and push bombing. In this edition, we dive into basic web application attacks.

Basic Web Application Attacks 101

A basic web application attack is an attempt to exploit vulnerabilities in a website or web app to gain unauthorized access, steal data, or disrupt service.

As organizations continue to migrate their operations to the cloud and rely heavily on web-based interfaces, the surface area for potential cyber threats has expanded significantly. Web applications power everything from online banking to internal business tools. Without proper fortification, they remain primary targets for malicious actors. Attackers are focusing their efforts on exploiting the applications themselves. Basic web application attacks are some of the most common methods threat actors use to compromise systems, steal data, and gain unauthorized access – and they don’t have to be complex. They exploit vulnerabilities in the application’s code, logic, or database connections.

These attacks often exploit vulnerabilities outlined by organizations like the OWASP, which tracks the most critical web security risks. The goal of these attacks varies, ranging from the theft of sensitive customer data and intellectual property to the total takeover of the administrative backend.

Understanding the fundamental methods attackers use to compromise these systems is the first step in building a resilient security posture. While there are dozens of techniques, let’s review the most common:

SQL Injection (SQLi): The attacker targets the server’s database and inserts malicious SQL code into an input field (like a login form or search bar). If the application does not properly sanitize this input, the malicious code is executed by the backend database, allowing the attacker to query, modify, or delete data directly from the database.
Cross-Site Scripting (XSS): The attacker targets the application’s users and injects malicious JavaScript into a webpage that other users then load. When a victim visits the compromised page, their browser executes the script, which can be used to steal session cookies, log keystrokes, hijack account credentials, or redirect the user to a fraudulent website. This works when applications don’t properly validate or escape user-generated content.
Broken Access Control: Access control ensures that users cannot act outside of their intended permissions. A failure in these controls—such as allowing a standard user to access an administrative URL or view another user’s private files—is known as Broken Access Control. This is a critical vulnerability that often leads to unauthorized information disclosure and data modification.
Broken Authentication: An attacker exploits weak passwords, session tokens, or login mechanisms to impersonate legitimate users — often through credential stuffing or brute force. This is made possible by oor password policies, lack of MFA, or predictable session tokens.
Cross-Site Request Forgery (CSRF): Attackers trick a logged-in user’s browser into making an unwanted request to a site they’re authenticated on. For example, while a user is authenticated in their banking app, they might click a malicious link in a different tab that triggers a hidden request to transfer funds. Because the user is already authenticated, the web application treats the request as legitimate. This can happen when applications trust requests from authenticated sessions without verifying their origin.

Basic web application attacks continue to persist and are so effective because they exploit fundamental weaknesses that are common across many organizations. Every internet-facing application represents a potential target for attackers, significantly expanding the available attack surface. Many of these attacks are also relatively simple to execute, often requiring minimal tooling and allowing threat actors to automate exploitation at scale. Despite their simplicity, the impact can be severe—even a single vulnerability may expose sensitive databases, compromise user accounts, or disrupt critical services. In many cases, these risks are amplified by human and development-related factors, including rushed deployment timelines, misconfigurations, and the absence of secure coding practices throughout the software development lifecycle.

Basic Web Application Attacks in the Wild

Most web application attacks follow a predictable lifecycle that allows threat actors to efficiently identify and exploit vulnerabilities. The process typically begins with reconnaissance, where attackers scan applications for exposed endpoints, login forms, APIs, and user input fields that may reveal potential weaknesses. Once areas of interest are identified, attackers move into vulnerability identification by testing inputs and application behavior for flaws such as injection points or insecure configurations. After discovering a viable weakness, the exploitation phase begins, during which attackers execute the attack by injecting malicious code, bypassing authentication controls, or hijacking user sessions. Successful exploitation is often followed by post-exploitation activity, including data exfiltration, privilege escalation, lateral movement, or establishing persistence within the environment. Because this process is structured and repeatable, web application attacks can be easily scaled across large numbers of targets.

The consequence of a successful web application attack includes: technical downtime, account takeover, data breaches, reputation damage, and financial loss.

Equifax

One of the most well-known examples of a web application attack occurred in 2017, when attackers exploited a vulnerability in the Apache Struts web application framework used by Equifax. The flaw allowed remote code execution through a vulnerable web application component. The breach exposed personally identifiable information (PII) of ~147 million individuals, including names, social security numbers, and birth dates. The incident highlighted how unpatched web application vulnerabilities can become entry points for large-scale data breaches.

Progress Software

In 2023, attackers exploited a SQL injection vulnerability in the MOVEit Transfer managed file transfer platform, allowing unauthorized access to sensitive data stored by thousands of organizations worldwide. The vulnerability was leveraged by the Clop ransomware group to extract data from government agencies, healthcare providers, universities, and financial institutions. The campaign ultimately impacted more than 2,000 organizations and exposed the data of nearly 100 million individuals, demonstrating how a single web application flaw can create widespread downstream impact.

Microsoft

In 2024, researchers identified a serious cross-site scripting (XSS) vulnerability in on-premises deployments of Microsoft Dynamics 365. The flaw allowed attackers to inject malicious JavaScript into application pages through improperly sanitized input fields. If exploited, attackers could execute scripts within victim browsers, potentially leading to session hijacking, credential theft, or unauthorized actions performed under legitimate user accounts. The incident reinforced that XSS remains one of the most persistent and commonly exploited web application vulnerabilities.

Protection and Mitigation

In many cases, it’s not advanced techniques that cause the most damage— it’s the fundamentals done poorly. To defend against a web application attack, organizations need to reduce risk with a combination of secure development practices and defensive controls:

Input Validation and Sanitization: Never trust user input—validate and sanitize everything. Implement strict validation rules to ensure only the expected data types are processed.
Use Parameterized Queries: Prevent SQL injection by separating code from data. Using parameterized queries (prepared statements) is the most effective way to prevent SQL injection.
Implement Output Encoding: Protect against XSS by properly escaping content. A strong CSP (Content Security Policy) can significantly reduce the risk of XSS by restricting the sources from which scripts can be loaded.
Enforce Strong Authentication: Use MFA, secure session management, and robust password policies.
Regular Patching and Updates: keep frameworks, libraries, and servers up to date.
Security Testing and Audits: Conduct frequent vulnerability scans and manual penetration testing to identify and remediate flaws before they can be exploited by threat actors. Incorporate static and dynamic analysis, penetration testing, and vulnerability scanning.
Follow Established Frameworks: Leverage guidance from OWASP, including the OWASP Top 10.