The Major Types of Software Vulnerabilities


Software vulnerabilities have evolved into a pressing concern for organizations. Attackers are continuously exploiting these weaknesses to gain unauthorized access to sensitive data on a daily basis. 

This unfolding landscape heralds the dawn of an era where malicious actors view every piece of software as a potential avenue to fulfill their nefarious objectives. Therefore, it comes as no surprise that cybercrime is on the rise at unprecedented rates.

A study by Positive Technologies reveals that 84% of web applications are vulnerable to unauthorized access, with 91% of the applications suffering data breaches. Does that mean software applications can no longer offer the desired data security?

Of course not! The truth is that cyber attackers are becoming more proactive in identifying loopholes faster than organizations are able to prevent them. Yet most organizations are unaware of how insecure their data is.

It takes an understanding of the vulnerabilities that attackers exploit to prevent them from gaining a chance. So, what chance do your software applications stand if attackers attempt to gain access to your sensitive information?

Not to worry, this article discusses the significant types of software vulnerabilities, how they occur and how attackers exploit them. You will also learn the best practices to prevent each type of software vulnerability.

If you are specifically keen on how to manage vulnerabilities instead, please check the key metrics for vulnerability management. For assessment, please check the vulnerability assessment methodologies.

Types of software vulnerabilities

Most software vulnerabilities stem from poor coding practices, software misconfigurations, and module interaction flaws.

While there are so many types of vulnerabilities, it’s easy to group them into specific categories, which makes it easy to understand them. 

There are five major categories, and we use these categories to discuss the critical vulnerabilities that all organizations need to be constantly aware of:

1. Code-based vulnerabilities

Code-based vulnerabilities, also known as coding weaknesses, emanate from coding errors when developing a software application. These mistakes weaken the codebase, opening a loophole for hackers to break into the system.

Coding mistakes can pave the way for buffer overflows, SQL injections, cross-site scripting, and insecure deserialization vulnerabilities.

Buffer overflows

Variables are allocated a fixed-size block of memory (buffer) when developing a computer program. The program can then store and retrieve data from the allocated memory capacity.

A buffer overflow occurs when the volume of data stored in a memory block exceeds the storage capacity, causing data to flow into adjacent blocks.

Attackers exploit buffer overflow by manipulating the execution stack of a web application. They cause the application to execute a malicious code given as input, eventually taking over the application.

SQL injection (SQLi)

Web applications usually receive user input via forms, URL parameters, or cookies. The input is then incorporated into SQL queries to interact with the database.

SQLi occurs when an attacker manipulates the user input with a malicious SQL snippet, querying the database. 

The executed malicious SQL query can bypass authentication checks, modify or delete user records, and potentially allow control over the database.

Let’s look at a simple login form query:

SELECT * FROM users WHERE username = 'input_username' AND password = 'input_password'

An attacker can manipulate the input by entering the following values:

  • Username: ' OR '1'='1’
  • Password: ' OR '1'='1’

So, the query is manipulated to: SELECT * FROM users WHERE username = '' OR '1'='1' AND password = '' OR '1'='1'

Since the condition  '1'='1’ returns TRUE, the attacker bypasses the authentication and gains unauthorized access to the system.

Cross-site scripting (XSS)

XSS emanates from poor handling of user-generated content such as comments, posts, or search queries. It occurs when an attacker manipulates the user's content so that it is treated as executable content instead of plain text.

The attacker injects a malicious program during the user’s browsing experience. Most of these malicious scripts are usually javascript snippets. What these scripts do is that they manipulate the active URL. So when a user interacts with the web page with malicious input, the script is executed on the browser.

Once the user clicks the URL, it allows the attacker to take over the user’s session. Once they take over, they can redirect the user to a targeted website, or gain access to sensitive information.

Insecure deserialization

Serialization is the conversion of data objects into a format that’s easily stored or transmitted, such as JSON, XML, or binary digits.

Deserialization is the reverse — converting serialized data into the original format, such as objects or data structures.

Insecure deserialization occurs when an application doesn’t validate or verify the deserialized data for integrity or authenticity.

The attacker gains access to the serialized data. They then manipulate the data with a specially crafted malicious program. 

The execution can lead to unauthorized access or data breach.

Code-based vulnerability prevention best practices

  • Use safe programming languages, such as Java, that automatically manage memory and bound-checking, preventing buffer overflow.
  • Employ secure coding practices like user input validation and using safe libraries. For a deeper dive into integrating security into your development lifecycle, read our SecDevOps article.
  • Regularly update and patch software to address any potential vulnerabilities
  • Employ the principle of least privilege (POLP) for database access
  • Sanitize (remove, encode, replace, or escape) unwanted user input to avoid potentially harmful inputs.
  • Use prepared statements (parameterized statements) to separate user input from SQL code.
  • Use techniques such as Content Security Policy to restrict the execution of scripts on webpages.
  • Implement digital signatures and integrity checks to prevent unauthorized access to serialized data.
  • Run deserialization in a sandboxed environment to contain any data breaches before they reach the live environment.
  • Keep a log of deserialization activities, including exceptions and failures

2. Configuration-based vulnerabilities

Configuration-based vulnerabilities occur when the configuration of a system or application is erroneously implemented or missing. This increases the risk of unauthorized access. 

Here are the three software development processes prone to exploitation due to misconfigurations.

Security misconfiguration

Attackers exploit security misconfigurations by exploiting weaknesses in the configuration of an application, server, or network.

The weaknesses include open ports, overly permissive permissions, default credentials, or unprotected sensitive files and directories.

Attackers employ automated scanning tools to discover misconfigured systems. Once they gain access, they can exfiltrate data and do much more harm.

Insecure API implementation

API misconfiguration occurs when the application programming interface of an application is poorly configured. The misconfiguration can happen during the design, implementation, or maintenance of the API.

There are various ways in which API misconfiguration can render an application vulnerable:

  • When APIs cannot verify user identity or enforce effective access control. Improper or weak authentication permits attackers to try bruteforce and credential stuffing, eventually gaining unauthorized access to the system.
  • When an API grants excessive permissions to functionality meant for a specified user or role, allowing activities beyond the user’s scope. 
  • APIs lacking rate limiting and throttling controls. This allows API request flooding, potentially causing denial of service (DoS), poor system performance, or unresponsive API.
  • Weak or misconfigured API session management exposes the system to session hijacking attacks.
  • APIs providing detailed error messages to users, involuntarily revealing the system’s architecture or vulnerabilities
  • Exposing API tokens, secrets, or keys in client-side code or publicly accessible repositories

Also read: API Attack Types & Vulnerabilities

Insecure file upload

Many web applications provide a feature that allows users to upload files, including images and documents.

File upload misconfiguration occurs when an application allows users to upload these files with inadequate control, validation, or security. Validation includes checking the file type, size, and content to ensure they are as expected.

Attackers can exploit file misconfiguration through the following means:

  • Malicious file upload: Attackers can upload files with malicious content, including malware, leading to security breaches. Even weak file configurations can allow attackers to apply double extensions (e.g., CV.php.pdf), disguising a malicious file as safe.
  • Overwriting existing files: File misconfiguration can also allow attackers to overwrite existing files on the server, including configuration files. This compromises the system, disrupting its performance.
  • Web shell upload: Attackers can upload scripts that permit remote code execution and gain control over the server to steal or compromise data.

Best practices to avoid configuration-based vulnerabilities

  • Conduct regular security audits to identify and rectify misconfigurations. You can use tools like Tenable Nessus and OpenVAS.
  • Implement custom error pages, and disable detailed error messages in production environments
  • Implement rate limiting to prevent request flooding
  • Perform thorough security testing, including penetration testing and vulnerability scanning, to identify and address API vulnerabilities
  • Monitor API usage and access logs to identify suspicious activities
  • Store uploaded files in a separate directory with restricted access and permissions
  • Use content-disposition headers to specify how the browser should handle downloaded files.

3. Design and logic-based vulnerabilities

These software vulnerabilities stem from flaws in the design or logical structure of a software application. This allows attackers to exploit a particular functionality within the system.

There are three significant attacks that can result from a design and logic flow vulnerability:

Authentication bypass

Authentication bypass stems from a poorly implemented authentication procedure. It can result from missing identity verification, weak password checks, or insufficient access control.

Attackers manipulate authentication tokens, session data, or user input to bypass login screens or authorization process flow. They disguise themselves as legitimate users.

Also read: What is Multi Factor Authentication and Why is it Important?

Directory traversal

A directory traversal is an exploit that involves an attacker accessing data stored in directories outside of the server’s root directory. 

The attacker gains access to restricted files and can execute commands on the server upon accessing the data directory.

Business logic flaws

These result from errors in the design and logic of an application rather than the technical implementation.

They occur when the application does not correctly enforce the intended business rules and processes.

Attackers exploit business logic flaws to alter the application’s intended behavior, gain unauthorized access, and perform malicious activities.

For instance, an attacker can change the price of a product in an ecommerce application.

Observe these best practices to prevent logic-based software vulnerabilities

  • Use unique session tokens and regular timeouts, and never store sensitive session data on client-side cookies
  • Enforce access level control for files and directories.
  • Maintain whitelists of allowed characters, directories, and file names to restrict the inputs the application should process.
  • Encrypt user’s session IDs and cookies to avoid stealing of confidential cookies
  • Avoid using external SQL interpreters, as they can be manipulated easily.
  • Conduct a thorough design review of the application to identify and address business logic flaws during development.
  • Involve end users in testing the application’s business logic to identify any mismatch in user requirements. 

Not sure which tools to use for testing? Check our guides on the best software testing tools as well as penetration testing tools

4. Software system interaction vulnerabilities

These vulnerabilities arise from the way software modules or systems interact with each other, including how they exchange data.

Here are the different ways attackers can exploit weaknesses in the system’s communication.

Cross-site Request Forgery (CSRF)

CSRF vulnerabilities occur when a web application cannot verify whether an authenticated user initiated an incoming request. It involves an attacker tricking a user into executing a malicious program on a different website against their consent.

Attackers exploit CSRF vulnerabilities by creating a malicious program and then tricking a victim into executing the program on a target website.

Attackers exploit CSRF vulnerabilities with the help of social engineering techniques. 

These techniques could include:

  • Incorporating a script into an HTML image tag
  • Injecting a malicious URL in the web pages the user accesses
  • Sending a malicious URL via email.

For instance, an attacker sends a malicious program to a victim. When the victim clicks the link, it redirects them to a website where the user is authenticated. 

The executed program allows the attacker to perform actions such as changing the user’s email and password against the user's consent.

XML External Entity (XXE) injection

XXE vulnerabilities occur when an application parses XML input from untrusted sources without validating it. This allows attackers to inject external entities into the XML data.

Attackers exploit XXE vulnerabilities by injecting external entities referencing malicious resources or files. This can lead to the extraction of sensitive information from the user and data breaches.

Also read: What is an XML Firewall?

Server-side Request Forgery (SSRF)

SSRF occurs when an application allows an attacker to make a random request from the server to internal or external resources. Attackers can manipulate these resources to gain unauthorized permissions and manipulate user data.

Interaction-based vulnerability prevention best practices

  • Implement anti-CSRF tokens in web forms to ensure that actions are only performed if a valid token matches the request.
  • Implement the SameSite cookie attribute to avoid cross-site requests sending user credentials.
  • Configure XML parser to disable the processing of external entities, especially in untrusted XML data.
  • Use modern and secure XML parsers that automatically disable external entity processing.
  • Maintain a whitelist of addresses and domains your applications can access rather than blacklist suspicious sites. Attackers can bypass blacklists. 
  • Use network segmentation to isolate the application’s internal resources from public access.

5. Other vulnerabilities

These are vulnerabilities that we feel do not necessarily fall into any of the discussed categories. They include: :

  • Information disclosure: This occurs when an application involuntarily reveals sensitive data to unauthorized users.
  • Privilege escalation: Enables an attacker to gain higher-level permissions or access rights for, say, an admin. They can then perform the roles assigned with the associated account privileges. To get a bigger picture on this, please read our resource on account takeover
  • Command injection: Allows attackers to perform malicious activities by processing an executable command. With the rise of AI, we are starting to see some other form of injection such as chatbot prompt injection
  • Race conditions: Occurs when multiple processes access shared resources concurrently in a competing order, leading to unpredictable outcomes.
  • Zero-day vulnerabilities: Security flaws executed by attackers before a software vendor releases a patch or becomes aware of the vulnerability.

Never make the mistake of waiting for the attacker to strike!

A  terrible mistake many organizations commit is to wait until an attack surfaces so they can take action. Never make this mistake.

This article is full of best practices you can complement immediately to keep your software off the attackers’ path.  Please implement them diligently and remember to constantly check back for more updates and latest trends. 

Finally, should you ever find yourself in the middle of a disaster, you will certainly need super good tools to get your operations out of the mess. For this, we have previously analyzed the most effective disaster recovery tools. Please spare a few minutes to check them out before you leave. For the remediation process, please go through these critical steps for remedying cyber threats.

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