An Attacker Performed a MITM Attack Against a Mobile Application

Multiple Choice

An attacker performed a MITM attack against a mobile application. The attacker is attempting to manipulate the application's network traffic via a proxy tool. The attacker only sees limited traffic as cleartext. The application log files indicate secure SSL/TLS connections are failing. Which of the following is MOST likely preventing proxying of all traffic?

A) Misconfigured routes
B) Certificate pinning
C) Strong cipher suites
D) Closed ports