In the recent ransomware attacks, attackers have asked the targeted organizations to pay them in bitcoins. How can they be anonymous if they deal in bitcoins? Can they convert bitcoins to any other currency?
There is lots of information about "bitcoin - anonymousity" on this site. I would recommend checking it out.
Cite from the website:
There are basically three ways to de-anonymize Bitcoin users.
First of all, even though Bitcoin transactions are randomly transmitted over the peer-to-peer network, this system is not airtight. If an attacker, for instance, has the means to connect multiple nodes to the Bitcoin network, the combined data collected from these different nodes might be enough to determine where a transaction originated.
Second, Bitcoin addresses can be linked to real identities if these real identities are used in combination with the Bitcoin addresses in some way. This includes addresses used to deposit or withdraw money to or from a (regulated) exchange or wallet service, publicly exposed donation addresses, or addresses simply used to send bitcoin to someone (including the online store) when using a real identity.
But perhaps most importantly, all transactions over the Bitcoin network are completely transparent and traceable by anyone. It's typically this complete transparency that allows multiple Bitcoin addresses to be clustered together, and be tied to the same user. Therefore, if just one of these clustered addresses is linked to a real-world identity through one or several of the other de-anonymizing methods, all clustered addresses can be.
Just as a side note: There are registers of reported bitcoin-addresses being used in attacks. So if a company gets a DDos threat, they can check if the address have been used before. If it is, the DDos threat is most likely fake. Because there is no way for the owner of the bitcoin account to see who has paid. This is just an example in how bitcoins can be used proactive.
Although Bitcoins are hardly anonymous - http://cryptorials.io/more-on-bitcoin-anonymity/ hackers know their ways. They use online exchanges to pass the money through several points. They also create tons of wallets and addresses.