An insurance company employs quick-response team drivers that carry corporate-issued mobile devices with the insurance company's app installed on them. Devices are configuration-hardened by an MDM and kept up to date. The employees use the app to collect insurance claim information and process payments.
Recently, a number of customers have filed complaints of credit card fraud against the insurance company, which occurred shortly after their payments were processed via the mobile app. The cyber-incident response team has been asked to investigate. Which of the following is MOST likely the cause?