There is a new wave of email-based attacks centering on OWA (Outlook Web Access) accounts, which are taking on a personal appearance. Security vendor Websense says they have seen upwards of 30,000 of these emails per hour.
The attacks start with an email that uses personalized TO: fields to imply the message is being sent from tech support. Victims in the attacks are asked to download a file that contains setting changes thanks to a recent security upgrade.
According to the scam, the emails start with, “We are informing you that because of the security upgrade of the mailing service your mailbox [redacted] settings were changed. In order to apply the new set of settings click on the following link:”
The emails will use the victim’s email domain as part of the link to the malicious site hosting the “settings updates.” In addition, the actual email domain is used consistently within the email message and the fake update site. Websense says that they have seen such customizations before, but they are uncommon.
Earlier this week, ISC handlers Mark Hofman and David Goldsmith describe attacks that mirror those seen by Websense, including a twist on the email message.
According to the ISC reports, earlier messages reported that, “On October 16, 2009 server upgrade will take place. Due to this the system may be offline for approximately half an hour. The changes will concern security, reliability and performance of mail service and the system as a whole. For compatibility of your browsers and mail clients with upgraded server software you should run SSl certificates update procedure…All you have to do is just to click the link provided, to save the patch file and then to run it from your computer location.”
In both the example from ISC and Websense, the Malware is a variant of the Zbot Trojan, but detection levels are still low.