There are direct and indirect methods of search engine search and education. Direct methods refer to searching the indexes and the corresponding content from the cache. Indirect methods refer to the collection of sensitive design and configuration information by searching forums, newsgroups, and website advertisements.

The intrinsic complexity of the networked and heterogeneous Web server infrastructure, which can include multiple Web applications, makes configuration management and review a fundamental step in testing and deploying each application. Only one vulnerability is needed to compromise the security of the entire infrastructure.

One of the core components of any web-based application is the mechanism that controls and maintains state for a user interacting with it. This is called session management and is defined as the set of all controls that govern the stateful interaction between a user and the application.

During a pentest of web applications we often encounter many error messages generated by applications or web servers. These error messages are very useful for attackers because they contain a lot of information about databases, errors, and other technological components that are directly connected to web applications.

In modern applications, it is common practice to define system roles to manage users and authorizations for system resources. Administrators represent a role that provides access to privileged and sensitive functions and information, while normal users represent a role that provides access to regular business functions and information.

Testing the transport of the credentials means checking whether the data is transmitted from the browser to the server unencrypted or whether the web application uses the appropriate security measures with a protocol such as HTTPS. The HTTPS protocol is based on TLS/SSL to encrypt the transferred data.

Many web applications use and manage data as part of their daily operations. With input validation methods that are not well designed or used, an attacker could exploit the system to read or write data that should not be accessible. In special situations, it may be possible to execute arbitrary system commands.

The most common vulnerabilities in web applications occur when user input is not properly validated. This weakness leads to almost all major vulnerabilities in Web applications, such as cross-site scripting, SQL injection, interpreter injection, local and Unicode attacks, file system attacks, and buffer overflows.

Sensitive data must be protected during transmission over the network. This data may include user data. Even if today's standard encryption is usually high-quality encryption, a misconfiguration can force weak encryption that allows an attacker to read sensitive data.

Testing for errors in business logic often requires unconventional methods. When the authentication mechanism of an application is developed, perform steps 1, 2, 3 in this specific order to authenticate a user. What happens if the user goes from step 1 directly to step 3?

Client-side testing deals with the execution of code on the client, typically natively in a web browser or browser plug-in. The execution of code on the client side differs from the execution on the server and the return of subsequent content. This involves testing for all common types of cross-site scripting.

Modern applications use an API to call micro services, perform actions or monitor user behavior. The design or structure of the API is often made publicly available to users. This structure allows the attacker to understand the API and use the information for further attacks.

The term patch management describes the strategic control for the import of system updates, which are used to close security gaps in software applications that are only detected after the market launch. Outdated software packages or frameworks from external sources should always be kept up-to-date.