Your Guide to Sensitive Data Exposure (Fuzzing) & How to Fix It

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The Online Web Application Security Project (OWASP) identifies the top 10 most critical web application security risks and provides guidance for their mitigation. Based on the frequency, severity, and magnitude of impact, these security lists are ranked, thereby helping organizations to use the guidelines and recommendations as part of their overall security strategy. Out of all those security risks, Sensitive Data Exposure is one such potential vulnerability that occurs when teams fail to sufficiently protect databases, exposing personal and critical information.

This article delves into sensitive data exposure risks, how attackers use Random Fuzzing/Fuzzer programs to exploit such risks, and various best practices and tools to mitigate such risks in modern application delivery. 

Security Assessment

Security Assessment Prevent Web Application Framework Information Leakage


What is Sensitive Data Exposure?

Sensitive data exposure is associated with how teams handle security controls for certain information. Missing or poor encryption is one of the most common vulnerabilities that lead to the exposure of sensitive data. Cybercriminals typically leverage sensitive data exposure to get a hold of passwords, cryptographic keys, tokens, and other information they can use for system compromise. Some commonly known flaws that lead to the exposure of sensitive data include:

Lack of SSL/HTTPS Security on Websites

As web applications gain mainstream use for modern enterprises, it is important to keep users/visitors protected. SSL Certificates are used to encrypt data between websites/applications and web servers. Organizations with misconfigured SSL/HTTPS security, risk compromising the users’ privacy and data integrity since it can easily be intercepted in transit.

SQL Injection Vulnerabilities in Databases

Without proper security controls, attackers can exploit malicious statements to retrieve the contents of a database. This allows them to create SQL statements that let them perform a wide variety of database administration actions. Hackers can retrieve sensitive information, such as user credentials or application configuration information, which they then use to penetrate and compromise the system further.

How Sensitive Data is Exposed

Most cyberattacks initially target vulnerabilities that expose sensitive data to gain a further foothold of the application stack. There are several threats that expose this information, whether it is on the move or at rest.

Sensitive Data at Rest

In a web application, data is typically stored in servers, files, databases, archives, networks, and other applications. The security of this data depends on the controls put in place to protect these components. Numerous types of attacks target unaddressed vulnerabilities in these components to access sensitive data. For instance, hackers can use Trojan Horses or Malicious Payloads to access system data via unauthorized downloads in the absence of a robust detection mechanism.

Sensitive Data in Transit

While data is moving between different services and applications, it remains vulnerable to attack vectors. Man-in-the-Middle (MITM) attacks are typically geared toward intercepting data moving between servers, channels, and APIs. It is important to secure channels that transmit data within the organization’s network, as these attackers could impersonate parties to access more sensitive data. 

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Methods of Accessing and Exposing Sensitive Data

While there can be a number of attack scenarios, hackers typically use a number of malevolent techniques, including:

Random Fuzzing

Random Fuzzing techniques automatically feed random, unexpected, or invalid input into applications then monitor the system for exceptions and bugs they can exploit. Attackers use a fuzzing process to target programs that accept structured queries, whereas a Fuzzing tool creates semi-valid input formats that can trick access control mechanisms but do not create enough unexpected behavior for detection.

Attackers can then explore the application’s ecosystem in search of sensitive data. To mitigate such attacks a Fuzz Testing mechanism, also known as Black Box Fuzzer testing method is employed that involves requires unexpected or random data to be entered as inputs to test the susceptibility of a target code. 

Phishing Attacks

Attackers frequently contact targets via email or text message, masquerading as legitimate users/organizations. The hackers pretend to be trusted sources, luring the targets to click on legitimate-looking URLs that typically lead to a login page. The targets are then convinced to input credentials that could be collected and used to orchestrate DDoS, Data Breaches, Hacks, and large-scale data theft.

Injection Attacks

Attackers craft SQL statements that trick database applications into performing undesired tasks. These attacks are used to change source code functions, thereby allowing attackers to access and retrieve sensitive data. By successfully injecting malicious payloads, hackers can easily gain access to unauthorized data and subsystems without detection.

Network Compromise

Attackers also aim to hijack user sessions, during which they can persist in their presence while avoiding detection. The presence of unidentified attackers within the network leaves the entire organization’s data in danger of exposure. When hackers attack a system, they often cover their tracks, leaving no trace of a compromise, reducing the network’s data integrity.

Insider Threats

Most organizations involve a complex human resource structure, with different employees having access to workloads of different sensitivity. Insider threats are security risks that originate from users within the organization. A disgruntled/indisciplined staff member with access to critical details can also initiate a data breach. Insider threats typically go unnoticed as most firms’ security efforts are focused on external threats.


Attackers use malicious software to encrypt a target’s files and then demand some form of ransom for them to retrieve the information. Ransomware attacks are staged by sending users an attachment or link that looks like it’s from a trusted source. Clicking the link integrates the Ransomware onto the device, keeping the data inaccessible to legitimate users.

Broken Access Control

Failures in access control implementation typically result in the disclosure of authentication information which allows attackers to perform business functions beyond their permissions. These attacks are common since they are difficult to detect with standard security scanning tools.

Examples of Sensitive Data Exposure Attacks

In the recent past, there have been a number of successful Sensitive Data Exposure attacks. 

The 2016 Data Breach

A hacker was reported to have obtained 171 million user accounts from various social media networks, having collected users’ names, email addresses, passwords, social security numbers, and phone numbers. This sensitive data breach was attributed to the use of plain-text passwords and is considered one of the most common vulnerabilities that are easily exploited.

The 2021 LinkedIn Data Hack

Attackers reportedly orchestrated a breach to expose the data of up to 700 Million (92%) of LinkedIn’s users. While doing so, attackers used scraping tools to collect user data and sell it online.

The 2018 Attack on DubSmash

Unidentified attackers gained unlawful access to the databases of Dubsmash and other websites. They placed up to 162 Million users’ records for sale on the dark web, and these included passwords and emails of various user accounts.

Preventing Sensitive Data Exposure

Exposure of sensitive data results in massive expenses for remediation, and an eventual loss of reputation for the affected organization. It is, therefore, important to enforce a strong, organization-wide culture toward preventing the exposure of sensitive data. 

The following section outlines the best practices and tools that can be used to prevent sensitive data exposure. 

Best Practices to Prevent Sensitive Data Exposure

The proliferation of information-driven applications has made cybercriminals shift their focus from web applications and servers to sensitive data. Some best practices to mitigate sensitive data exposure vulnerabilities include:

Identify and Classify Sensitive Data

It is important to determine and classify sensitive data with extra security controls. This data should then be filtered by the level of sensitivity, and then be secured with the appropriate security controls. 

Apply Access Controls

Security teams should focus their energy on the processes of authentication, authorization, and session management through the provisioning of a robust Identity and Access Management (IAM) mechanism. With the right access controls in place, organizations must ensure that only the intended individuals can view and modify sensitive data.

Perform Proper Data Encryption with Strong, Updated Protocols

Sensitive data should never be stored in plain text. It is important to ensure that user credentials and other personal information are protected using modern cryptographic algorithms that address the latest security vulnerabilities. 

Store Passwords Using Strong, Adaptive, and Salted Hashing Functions

Given the advancement of security controls, attackers have also devised clever ways to retrieve passwords. For instance, a hacker can use a rainbow table of precalculated hashes to access a password file that uses unsalted hashes. Salted hashes enhance password security by adding random inputs to a hash function, guaranteeing a unique output, and are thus recommended over unsalted hashes.

Disable Caching and Autocomplete on Data Collection forms

While caching and autocomplete features help improve user experience, they contain security risks that may attract attackers. Hackers may rely on a user’s browser to log in to an account easily since the autocomplete feature fills in the credentials.

Caching stores sections of web pages for easier loading in subsequent visits, which allows attackers to use it to map out a user’s movements. Attackers also use cache data to tailor malware. As a best practice, it is recommended that caching and autocomplete of forms are disabled by default, and only activated as needed.

Minimize Data Surface Area

Security teams should reduce the system’s data attack surface area by considering careful API design, ensuring only the bare minimum amount of data is included in server responses. While doing so, it must be also ensured that the server response does not expose information about the system’s configuration. Random testing and Data filtering should also be performed at the server-side to reduce the risk of attackers intercepting sensitive data in unfiltered traffic in transit.

Some popular solutions that offer various detection techniques while remediating and preventing sensitive data exposure include:

Crashtest Security

An automated end-to-end vulnerability scanning solution that helps improve security posture by benchmarking web applications against the OWASP Top 10. With Crashtest Security, organizations can set up vulnerability scanning within minutes as the suite integrates seamlessly with most current tech stacks. In addition, the tool enables efficient scanning with low false positive & negative rates while producing accurate vulnerability reports and remediation advice.

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A highly matured security testing platform with inbuilt vulnerability management and assessment. The Acunetix platform comes with easy integrations for simpler adoption into the CI/CD pipelines. With its own API, the tool also supports integration with other security platforms.

Burp Suite

PortSwigger’s Burp Suite helps organizations automate and scale vulnerability scanning to help protect web applications against zero-day threats. The suite benefits from the research of numerous penetration testers and bug bounty hunters, regularly discovering and fixing vulnerabilities before attackers exploit them.


An all-in-one security management platform that uses runtime data flow techniques to detect vulnerabilities before they are discovered by attackers. Hdiv automates self-protection throughout the application’s lifecycle, reducing the need for massive investment in security personnel and products.

Immuniweb Discovery

An attack surface management platform that provides an accurate assessment of the application’s security posture. The tool performs tasks such as Dark Web Incident Monitoring, AI-powered attacks, non-intrusive discovery, and third-party risk management.


Since hackers need no special skills to access data that isn’t properly secured, sensitive data exposure continues to be one of the most common attacks in the past few years. While there are regulatory compliances such as Protection of Personally Identifiable Information (PII) and GDPR that enforces security standards, organizations must formulate a detailed cybersecurity strategy along with adopting the best practices and tools. 

Crashtest can help organizations manage sensitive data by implementing a continuous testing process that seamlessly integrates with an existing development workflow. Try Crashtest Security Suite today to discover how automated vulnerability scanning can help your organization reduce the risk of exposing sensitive data.