ZeuS Downloader Runs in January, Crashes Rest of the Year

A few weeks ago, we received a rather unusual malicious attachment, which we detect as TROJ_UPATRE.SMAI. This particular attachment, when uncompressed and executed, displays the following error message: Figure 1. Error message At first glance, this may lead users to think it is not malicious. However, if we look into its code, one item stands…