Understanding Common Vulnerabilities in Public-Facing Applications

In today’s digital landscape, public-facing applications have become essential tools for delivering services to customers and managing workflow. However, its widespread use comes with significant risks. Throughout 2024, K logix threat experts have been tracking cyber threats and vulnerabilities. So far in 2024, exploiting public-facing applications (MITRE T1190) ranks as the second most common way for threat actors to gain initial access to systems. 

Exploiting public-facing applications involves targeting vulnerabilities within web applications that are accessible over the internet. From e-commerce sites to cloud-based platforms, these applications handle sensitive user data and support critical business operations. Recently, K logix has observed cybercriminals taking advantage of cross-site scripting, SQL injection, and use-after-free vulnerabilities in public-facing applications to manipulate the application’s behavior. By successfully exploiting these vulnerabilities, cybercriminals can gain initial access, establishing a foothold into its victims’ systems to execute arbitrary code or extract sensitive information. Understanding the tactics these attackers use and the specific vulnerability types they exploit is essential for organizations looking to strengthen their cybersecurity posture.  

Common Vulnerabilities Leading to Exploited Public-Facing Applications: 

Cross-Site Scripting (XSS) 

XSS vulnerabilities allow attackers to inject harmful scripts into web pages viewed by other users, leading to serious issues like data theft and session hijacking. For instance, if a web application fails to properly check user input, an attacker might inject a script that captures user credentials or redirects users to malicious sites. This was the case in a cyber espionage campaign by the Winter Vivern group which exploited XSS vulnerabilities in Zimbra Collaboration to target government entities in Moldova, Tunisia, Ukraine, and Poland. In November 2023, Google’s Threat Analysis Group identified the XSS vulnerability (CVE-2023-37580) in Zimbra, which was allowing attackers to inject malicious scripts through URL parameters. When users clicked on these compromised links, the scripts executed in their browsers, potentially granting unauthorized access to sensitive data or manipulating user sessions.  

To mitigate XSS risks, organizations should implement proper input validation and output encoding. Input validation ensures that user input meets specific criteria for that input type, such as containing an “@” symbol in an email address field. Output encoding transforms user input to prevent it from being executed as HTML or JavaScript. Additionally, employing a Content Security Policy (CSP) can further enhance protection against XSS attacks by controlling which scripts can run on a web page. 

SQL injection 

SQL injection is another prevalent vulnerability that occurs when attackers manipulate input fields in a web application to execute arbitrary SQL commands. For example, by entering malicious SQL code into a login form, an attacker could bypass authentication checks and extract sensitive data. SQL injection is dangerous because it can lead to complete database compromise, allowing attackers to steal, alter, or delete critical information. In 2017, Equifax suffered a massive data breach primarily caused by SQL injection vulnerabilities in its web applications. Cybercriminals exploited these weaknesses to gain unauthorized access to sensitive information of around 147 million customers, including social security numbers, birth dates, and addresses. As a public facing application, Equifax’s systems were critical for processing financial data, making them an appealing target for attackers. 

To defend against SQL injection attacks, organizations should use prepared statements with parameterized queries. This will help ensure that the database can distinguish between regular user input and harmful commands.   

 Use-After-Free 

Use-After-Free vulnerabilities occur when a program continues to use memory resources after they have been freed. This can enable various attacks, including arbitrary code execution and memory corruption. Public-facing applications that manage complex user interactions are particularly vulnerable because they rely on dynamic memory, which means they allocate and free up memory as needed during their operations. In 2020, Apple Safari was targeted by a critical use-after-free vulnerability in its WebKit engine. This flaw occurred when the memory linked to an object was released while still being referenced, allowing the attackers to manipulate the browser's memory. This use-after-free attack capitalized on the browser’s widespread usage, affecting millions of users who relied on Safari for their online activities. 

To protect from a use-after-free vulnerability, MITRE recommends using a programming language that has automatic memory management and setting pointers to NULL once they are freed. This practice helps prevent accidental access to memory that should not be used anymore.  

Exploiting vulnerabilities such as XSS, SQL injection, and use-after-free in public-facing applications, enables attackers to gain initial access to systems, posing significant risks to organizations. To defend against these vulnerabilities, organizations much adopt robust security measures such as conducting regular vulnerability assessments and implementing secure coding practices. Understanding and addressing these common vulnerabilities is vital for maintaining the integrity of public-facing applications and protecting sensitive user data.