Coincenter just released a new article on the topic of malicious images on blockchains. Due to the nature of how blockchain technology works and also due to how policy works this is an area of upcoming conflict. Because this conflict can be predicted in advance it gives both sides time to prepare their arguments. Steemit in particular has an open blockchain and "contraband bits" including malicious images may be uploaded onto Steem. The fact that Steem does not rely on any kind of encryption means anyone anywhere on earth can both upload anything and or access anything (including contraband bits).
A quote from the article:
There have been several press reports this week claiming that illegal images are stored on the Bitcoin blockchain, thus potentially creating a liability for anyone who has a copy of the blockchain. The articles cite a recently published academic paper, but the fact that arbitrary data can be included in the blockchain is not new. It is a phenomenon that a simple a Google search would have revealed has been well understood since at least 2013 if not earlier, and the facts of the matter are not as damning as recent headlines suggest. We are disappointed that so many are jumping to conclusions about what it means for Bitcoin that some despicable people have exploited it and linked it to the scourge of child pornography.
This issue is complicated specifically because the more law enforcement attempts to crack down on contraband bits the more demand there will be for "bitmasking" which in other words are methods of obfuscating. So from a practical point of view there seems to be no way to actually enforce this because data can always be encoded into any form which isn't considered contraband bits (such as numbers) and then converted back to contraband bits using some kind of plugin. On Steem this would be trivial to implement if people aren't already doing it and we wouldn't have a way to stop it or even see it.
The most obvious example is Base64 which the article used. The truth is any code can be translated into another code (information is never created or destroyed). The illegal bits therefore will just be masked if there is a crackdown and the crackdown likely solves absolutely nothing.
The article summarizes this point:
While evil people will always exploit technology to do evil things, we shouldn’t succumb to a moral panic and fall in the trap of blaming the technology for that evil. This technique of including arbitrary data in the Bitcoin blockchain that is sporadically being used perversely is the same technique that is being used systematically every day to do socially beneficial record notarizing, like tracking land title on the blockchain.
How does Steem solve this problem?
The Steemit solution is to suppress controversial or contraband bits by allowing the crowd to use the mechanism of collaborative filtering (downvoting) to express disapproval. An evil or illegal image would likely be downvoted into oblivion and there would be no possibility of someone getting paid for sharing it. This in my opinion is one of the reasons the downvote aka flag exists and I would use the flag feature particularly for this purpose. If you see something which you know is illegal uploaded on the Steem blockchain or if it is legal but violates your conscience then you have the ability in either of these cases to "do the Right Thing".