WhoisXML API Blog

IP addresses are straightforward input data for IT security investigations: they are technically necessary for nodes of the Internet to communicate. Hence, if they are not deleted in some tricky way after cybercrime has been committed, or they are to be found in any of the logs before the commitment, they help a lot to unfold what has actually happened. 

IBM Xforce exchange is a forum reporting many security incidents that are relevant for those who are in charge of maintaining IT security. In the present blog we shall pick one of their reports and check how we can extend the given information with WhoisXML APIs using PowerShell which comes installed on Windows and can be used on Linux and Mac OS X, too. We assume lower intermediate skills of PowerShell programming to follow the description below. 

PowerShell is a powerful cross-platform interpreter for scripting that can be used for automating the tasks. On Windows systems in particular, it is the primary and native tool for system administration, data processing, and many more activities. The possibilities range from simple scripts to implement command-line solutions to large, object-oriented tasks. 

This blog is an invitation to use WhoisAPI’s services in PowerShell. This consists of using RESTful APIs, illustrating the power of the actual services, especially in security and domainer applications. The presentation is aimed at beginners with a very basic background in programming, and no background in PowerShell is assumed. However, experts of PowerShell who have not used RESTful APIs yet, and experts with a UNIX background making their first steps with PowerShell may also find it useful. 

Passive DNS introduced by Florian Weimer in 2005 is now a central resource in IP security investigations, security of the operation of the domain name system (DNS), and many more. A Passive DNS database contains observed events whenever an IP resolves to a domain name in a DNS communication. Hence, it is a database independent from the current state as well as the physical infrastructure of the DNS itself. In addition, it contains time information: the date and time when such a resolution was first and last observed; this cannot be found out from the DNS. 

One of the easiest ways to obtain such data is by using WhoisXML API’s services. In the present blog, we focus on the reverse lookup: using an IPv4 address we want to reveal the domain names that these IPs belonged to on certain dates. 

In what follows, we’ll develop a small Python program based on WhoisXML API’s email verification package, python-email-verifier that returns the valid and working abuse e-mail of an Internet domain if it exists.