http://www.interpol.int/News-and-media/News/2015/N2015-033
EDIT Admittedly this is a little sci fi but I was thinking more or less about LE being able to "flag" transactions and follow them through the blockchain, identifying the bitcoins as they move through the system.
My understanding of the bitcoin system and IT is pretty limited (but I'm learning!) so apologies in advance if this is just silly. :-)
Luckily the Bitcoin blockchain is more of a Medusa than any Bittorrent data and look how well taking those down works.
Focussing on "malware" in this text is a cheap trick in trying to scare away users from Bitcoin. This CP bullshit has been around for some time. It's another attempt to scare people away and to form arguments for legislators to put restrictions on the technology. Didn't work, isn't going to work. The ledger has always been public and they can't do shit about DNM activities as long as people watch their OPSEC.
Pandora's box has been opened and freedom will prevail.
Kill all they send and they will stop coming.