"In continuation of our support for the takedown activities on the Win32/Afcore botnet, we are releasing a second edition of MSRT in April," announced Microsoft. "This edition includes variants of Afcore released by the criminals behind it at approximately the same time as the previous edition of MSRT. While MSRT has traditionally been released on the second Tuesday of the month alongside other security releases, we're not tied to this schedule."
"We can, and will, release MSRT as needed to support takedown activities or other times when the impact will be potentially significant. This additional release is on request and we welcome other requests in the future," Microsoft added.
This release also includes some additional enhancements to the MSRT engine for other malware families, which have also been incorporated into definitions for Microsoft Security Essentials and the Forefront products since the last MSRT release.
[Source: MMPC blog]