US-CERT is aware of reports of malware using social engineering to propagate. Spam appearing to come from “admin@microsoft.com” contains a link to a malicious file that claims to be an installer for Internet Explorer 7. Typically the file is named “IE7.0.exe” and if executed installs a rootkit on the target machine.US-CERT encourages users to take the following preventative measures to help mitigate this risk:
Do not follow unsolicited links in email messages.
Install anti-virus software, and keep its virus signature files up-to-date.
Review the Reducing Spam Cyber Security Tip.
Review the Avoiding Social Engineering and Phishing Attacks
Cyber Security Tip.
US-CERT will continue to investigate and provide additional information as it becomes available.

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Source: US CERT