Trusteer researcher Tanya Shafir has recently identified an active configuration of TorRat targeting Twitter users. This worm launches an attack of the type Man-in-the-Browser (MitB) through an infected computer browser to gain access to the Twitter account of the victim, and then post tweets. The malware was used to grab user credentials and access your financial transactions, but now uses the data network to send links to malware sites.
So far we know that the attack is contained within the Netherlands market. Tweets were detected only in Dutch, but due to the popularity of Twitter, any time it can be used with other languages in different countries.
For now there is no official Twitter news on this subject.