te is issued incorrectly or fraudulently, which can allow the browser to take preventive actions. Identification of IP-ranges and domain names used by the organization. By scanning the ranges and DNS-systems, running services can be discovered. Outdated services or misconfigurations can be abused to obtain access to the infrastructure of the organization in a later attack stage. Zone walking is a technique which allows attackers to read the full content of DNSSEC- signed (Domain Name System Security Extensions) DNS zones. As a result, sensitive data like customer lists (subdomains) and IP addresses of servers can leak. Shodan is a search engine that lets attackers find specific types of hosts, such as embedded webservers, connected to the internet using a variety of filters. Knowledge of the IP address(es) of the internet router is essential for a targeted attack on a company network. This information can be retrieved, for example, by analyzing emails or via access to the wireless guest network. In addition to data about servers/applications and people, extra information can be found on the internet that can be useful for a cyber-attack, such as technical documentation, financial data and previously leaked account (and password) information. File enumeration is a technique for retrieving publicly accessible files in order to gather information about the target. It is not required that there are references to the files on, for example, a website. This attack is also known as Predictable Resource Location, Directory Enumeration, and Resource Enumeration. Web archives search are used by attackers to look back in time at the various stages of the website or application. This can provide information about the changes made on a website (e.g., vulnerabilities that have been fixed, an old CMS moved to a different path), but it also makes clear what growth a company has had. Additionally, archives also can be a source to identify email addresses, names, phone numbers, addresses, and SO on. Some sources contain information