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Top 10 Vulnerabilities In Web Apps You Can Prevent With Testing

When talking about cyber risks, the first thing you might think of is malware. However, many cyber-attacks are linked to apps. According to the Positive Technologies data, users can be attacked by hackers in 9 out of 10 web applications. Many attacks though, would be impossible without the weaknesses in the software that could be misused.

In order to improve the quality and security of applications, the community project “Open Web Application Security Project” (OWASP) was launched. There are various sub-projects within the OWASP, and one of them is the OWASP Top Ten Project,” which describes the most critical vulnerabilities of web apps. In this blog, we provide a list of the most common errors related to application security. This information will help you to understand the most important aspects of building a secure app that users will trust.

The Most Common Web Application Vulnerabilities

Here are the Top 10 web app vulnerabilities according to the OWASP data.


A simple failure to filter the untrusted inputs leads to the problem called injection flaws. Injection vulnerabilities, such as SQL, OS, or LDAP injection, occur when an interpreter processes untrustworthy data as part of a command or query. Attackers, therefore, have an opportunity to manipulate input data. More precisely, they can access data without authorization or even execute system commands.

Broken Authentication And Session Management Vulnerabilities

This is quite a common vulnerability that refers to the set of various issues that might happen Access control error during broken authentication. Why does it occur? Developers often implement app functions related to authentication and session management incorrectly. This allows hackers to compromise passwords or session tokens or to exploit the corresponding vulnerabilities in such a way that they can temporarily or permanently impersonate other users.

Sensitive data exposure


Many apps do not adequately protect sensitive information, such as personal, financial, or health data. Attackers can read out or modify this data and use it to commit a further crime, for example, credit card fraud, identity theft, etc. Confidential data, therefore, should always be protected with the help of encryption.

XML Vulnerabilities

Many outdated or poorly configured XML processors consider references to external entities within XML documents. This allows such external entities to be used to disclose internal files with the help of the file URI handler, internal port scanning, internal file shares, denial-of-service attacks, and remote code execution. This way, the hackers can get access to the files on the apps’ server filesy stems or connect to any other system apps have access to.

Access control error

The access rights for authenticated users are often implemented or enforced in the wrong way. Attackers can use vulnerabilities to access functions or data for which they are not authorized. This can be access to users’ accounts and other confidential data. The attackers can then manipulate the user data, for example, making changes to their information or modify the access rights.

Security Misconfiguration

Applications are often configured in the wrong way. This results in insecure standard configurations, incomplete or ad hoc configurations, unprotected cloud storage, misconfigured HTTP headers, and error messages that contain confidential data. It is essential not only to ensure the secure configuration of each operating system, framework, library, or app but also to ensure their timely patch/upgrade.

Cross-Site Scripting XSS

XSS occurs when applications receive untrusted data and send it to a web browser without validation or recoding. XSS also happens when an application generates HTML or JavaScript code based on user input. XSS allows an attacker to execute script code in a victim’s browser and thus take over user sessions, display changes to page content, or redirect the user to malicious pages.

Insecure Deserialization

Unsecured deserializations that have not been appropriately verified can lead to remote code execution vulnerabilities. But even if that is not the case, deserialization errors can allow attack patterns such as replay attacks, injections, and the sneaking of extended access rights.

Use of components with Known Vulnerabilities

We can look at this vulnerability as a maintenance issue. Components such as libraries, frameworks, etc. are executed with the permissions of the associated app. If a vulnerable element is used, such an attack can lead to significant data loss and even a system takeover. Applications and APIs that use components with known vulnerabilities can circumvent protective measures and thus cause attacks with serious effects.

Insufficient Logging & Monitoring

Inadequate logging and monitoring, combined with a lack of or ineffective response to incidents lead to ongoing or repeated attacks. This also allows attackers to penetrate networks further and steal, change, or destroy data.

This by far is not a complete list of the vulnerabilities associated with apps. Another good example is the issue called unvalidated redirects and forwards This vulnerability, which is sometimes called Open Redirect, occurs when an app accepts untrusted input and send a visitor to an untrusted source (testing for unvalidated redirects and forwards can help solve this problem).

Final Thoughts

Security matters. If security aspects are not taken seriously, it inevitably leads to the vulnerability of your software product and therefore to hacker attacks. The consequences of attacks can vary strongly: from obvious data or money loss to more extreme such as an entirely ruined reputation of your company. The best way to avoid such scenarios is to find a reliable testing and QA provider that will ensure the quality and security of your app.

We‘ve been providing various testing services for more than 19 years. Our highly professional testers have delivered over 300 successful projects for businesses of different sizes and from different industries. If you need help with testing your application — or any other software — write to us.

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