Fraudsters are abusing a Google Calendar feature that’s commonly enabled on smartphones to target unsuspecting users with scam offers.
Kaspersky Lab came across the scam campaign after observing unsolicited pop-up calendar notifications targeting some of its mobile users via Gmail in May. Upon taking a closer look, the security firm found that these notifications abused a Gmail feature that’s commonly enabled by default on smartphones: the automatic addition and notification of calendar invitations within the mobile Gmail app. Fraudsters leveraged this capability to display a notification for their invitations on the home screen of each targeted smartphone user. These notifications encouraged users to click on a link included with the invitations.
When a user clicked the link, the attack chain redirected them to a website that offered prize money in exchange for filling out a questionnaire. This survey contained questions designed to steal users’ personal information, including their names, phone numbers and addresses. It also instructed users to complete a “fixing payment” with their credit cards, payment data that the scammers could then abuse to commit credit card fraud.
Calendar-Based Phishing Schemes
This scam campaign was unique in that it leveraged a common feature associated with the mobile Gmail app to deliver phishing calendar invitations. Even so, this was not the first calendar-based phishing scheme in general. All the way back in 2008, Naked Security came across a sample in which digital attackers used Google Calendar invitations to steal credentials. In January 2019, GMX found that calendar spam accounts had grown to account for 7 percent of all digital appointment invitations received by users.
How to Defend Against Mobile-Borne Scam Offers
Security professionals can help defend against mobile-borne scam offers by using ahead-of-threat detection to block malicious domains, including phishing attack landing pages, before they become active in ongoing attacks. Companies should also use ongoing employee awareness training to teach employees about common social engineering techniques.