A new phishing campaign has been detected that uses calendar invitations to steal banking and email credentials. The messages in the campaign include an iCalendar email attachment which may fool employees as this is a rare file type for phishing. These attachments are therefore unlikely to have been specifically covered in security awareness training.

iCalendar files are the file types used to store scheduling and calendaring information such as tasks and events. In this case, the messages in the campaign have the subject line “Fault Detection from Message Center,” and have been sent from a legitimate email account that has been compromised by the attackers in a previous campaign.

Because the email comes from a legitimate account rather than a spoofed account, the messages will pass checks such as those conducted through DMARC, DKIM, and SPF, which identify email impersonation attacks where the true sender spoofs an account. DMARC, DKIM, and SPF check to see if the true sender of an email is authorized to send messages from a domain.

As with most phishing campaigns, the attackers use fear and urgency to get users to click without considering the legitimacy of the request. In this case, the messages include a warning from the bank’s security team that withdrawals have been made from the account that have been flagged as suspicious. This campaign is targeting mobile users, with the messages asking for the file to be opened on a mobile device.

If the email attachment is opened, the user will be presented with a new calendar entry titled “Stop Unauthorized Payment” which includes a Microsoft SharePoint URL. If that link is clicked, the user will be directed to a Google-hosted website with a phishing kit that spoofs the login for Wells Fargo bank. Both of these websites have valid SSL certificates, so they may not be flagged as suspicious. They will also display the green padlock that shows that the connection between the browser and the website is encrypted and secure, as would be the case for the genuine bank website.

The user is then asked to enter their username, password, PIN, email address, email password, and account numbers. If the information is entered it is captured by the attacker and the information will be used to gain access to the accounts. To make it appear that the request is genuine, the user will then be directed to the legitimate Wells Fargo website once the information is submitted.

There are warning signs that the request is not genuine, which should be identified by security conscious individuals. The use of SharePoint and Google domains rather than a direct link to the Wells Fargo website are suspect, the request to only open the file on a mobile device is not explained. The phishing website also asks for a lot of information, including email address and password, which are not relevant.

These flags should be enough to convince most users that the request is not genuine, but any phishing email that bypasses spam filtering defenses and is delivered to inboxes poses a risk.