Microsoft recently fought back against more than 1,400 Citadel botnets by sinkholing their Command and Control (C&C) infrastructure. 51% of the 72 domains analysed did not appear in Microsofts published list. This implies either that the sinkhole was unsuccessful or that the domains have already been re-appropriated by the Citadel botnet owners. However, the long-term affect of this particular takedown on Citadel is unlikely to be significant: it looks as though many of the botnets werent knocked out.”]
Source: https://nakedsecurity.sophos.com/2013/06/12/microsoft-citadel-takedown/