  The Domain Name System (DNS) was created to resolve the IP addresses of the
web servers to easily remembered names. When it was initially created, security
was not a major concern; nowadays, this lack of inherent security and trust has
exposed the global DNS infrastructure to malicious actors. The passive DNS data
collection process creates a database containing various DNS data elements,
some of which are personal and need to be protected to preserve the privacy of
the end users. To this end, we propose the use of distributed ledger
technology. We use Hyperledger Fabric to create a permissioned blockchain,
which only authorized entities can access. The proposed solution supports
queries for storing and retrieving data from the blockchain ledger, allowing
the use of the passive DNS database for further analysis, e.g. for the
identification of malicious domain names. Additionally, it effectively protects
the DNS personal data from unauthorized entities, including the administrators
that can act as potential malicious insiders, and allows only the data owners
to perform queries over these data. We evaluated our proposed solution by
creating a proof-of-concept experimental setup that passively collects DNS data
from a network and then uses the distributed ledger technology to store the
data in an immutable ledger, thus providing a full historical overview of all
the records.
