campaign is to obtain users’ Office 365 passwords.

The phishing campaign was detected by ISC Handler Xavier Mertens and the campaign appears to still be active.

The phishing emails closely resemble legitimate Office 365 non-delivery notifications and include Office 365 branding. As is the case with official non-delivery notifications, the user is alerted that messages have not been delivered and told that action is required.

The Office 365 phishing emails claim that “Microsoft found Several Undelivered Messages” and attributes the non-delivery to “Server Congestion.” The emails ask the sender to retype the recipient’s email address and send the message again, although conveniently they include a Send Again button.

If users click the Send Again button, they will be directed to a website that closely resembles the official Office 365 website and includes a login box that has been auto-populated with the user’s email address.

If the password is entered, a JavaScript function sends both the email address and password to the scammer. The user will then be redirected to the genuine outlook.office365.com website where they will be presented with a real Office 365 login box.

While the Office 365 phishing emails and the website look legitimate, there are signs that all is not what it seems. The emails are well written and the sender’s email – postmaster@us.ibm.com – looks official but there is irregular capitalization of the warning message: Something that would not occur on an official Microsoft notification.

The clearest sign that this is a phishing scam is the domain to which users are directed if they click on the Send Again button. It is not an official Microsoft domain (agilones.com).

While the error in the email may be overlooked, users should notice the domain, although some users may proceed and enter passwords as the login box is identical to the login on the official Microsoft site.

The campaign shows just how important it is to carefully check every message before taking any action and to always check the domain before disclosing any sensitive information.

Scammers use Office 365 phishing emails because so many businesses have signed up to use Office 365. Mass email campaigns therefore have a high probability of reaching an Outlook inbox. That said, it is easy to target office 365 users. A business that is using Office 365 broadcasts it through their public DNS MX records.

Businesses can improve their resilience to phishing attacks through mandatory security awareness training for all employees. Employees should be told to always check messages carefully and should be taught how to identify phishing emails.

Businesses should also ensure they have an advanced spam filtering solution in place. While Microsoft does offer anti-phishing protection for Office 365 through its Advanced Threat Protection (APT) offering, businesses should consider using a third-party spam filtering solution with Office 365.

SpamTitan provides superior protection against phishing and zero-day attacks, an area where APT struggles.