  The increase of Internet services has not only created several digital
identities but also more information available about the persons behind them.
The data can be collected and used for attacks on digital identities as well as
on identity management systems, which manage digital identities. In order to
identify possible attack vectors and take countermeasures at an early stage, it
is important for individuals and organizations to systematically search for and
analyze the data. This paper proposes a classification of data and open-source
intelligence (OSINT) tools related to identities. This classification helps to
systematically search for data. In the next step, the data can be analyzed and
countermeasures can be taken. Last but not least, an OSINT framework approach
applying this classification for searching and analyzing data is presented and
discussed.
