Arbitrary blockchain content

Bitcoin's blockchain can be loaded with arbitrary data. In 2018 researchers from RWTH Aachen University and Goethe University identified 1,600 files added to the blockchain, 59 of which included links to unlawful images of child exploitation, politically sensitive content, or privacy violations. "Our analysis shows that certain content, eg, illegal pornography, can render the mere possession of a blockchain illegal."

Interpol also sent out an alert in 2015 saying that "the design of the blockchain means there is the possibility of malware being injected and permanently hosted with no methods currently available to wipe this data".