How does the new voicemail phishing scam work?

There's a new malware attack that uses voicemail to infect victims. Can you explain how this attack works? How can enterprises detect and defend against this voicemail-leveraging malware?

Very few exploits outside of social engineering have been delivered via plain-old-telephone service, but modern criminals have found a way to trick people through a new voicemail phishing scam. The modern twist is that the voicemail is delivered as an attachment on an email. For this to work, the attacker sends a phishing email designed to look like a legitimate email notifying the recipient he has a voicemail; the fake voicemail notification email carries a malicious attachment and when the recipient opens the voicemail file, the malware executes on the endpoint.

Enterprises can detect and defend against voicemail-leveraging malware by using an antispam or antiphishing scam tool that monitors for malicious emails. Alternatively, they could use a network based antimalware tool that blocks either a potential download of the malware, or the command and control communications.

Enterprises should also train their users to be more judicious about opening any attachments that look legitimate. Multifunction printers, fax machines, voicemail and other systems that send notifications via email should be configured with relevant details and branding for the enterprise to help employees identify phishing scams. A targeted attack could spoof the proper configuration and branding, but it increases the resources needed for the attack. In their security awareness training, enterprises should include that users should be skeptical of attachments that seem out of context from the sender.

These same defenses can be used against phishing scams disguised as a scanned document, fax or many other types of email notifications, including gift card notifications.

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