During an internal investigation at a healthcare billing firm in Denver, Colorado, the security team...

The correct answer is D. SIMjacker.

SIMjacker is a mobile attack technique that uses specially crafted binary SMS messages targeting SIM-card functionality, historically associated with the S@T Browser environment. The attack can trigger device actions without visible user interaction, including collecting location or device information and sending it to an attacker-controlled destination.

The scenario states that the device received binary-formatted SMS messages, the messages were not visible to the user, and the phone automatically transmitted cellular location identifiers and device-related data. These are the strongest indicators of SIMjacker.

CEH-aligned mobile security material identifies SMS-based attacks and mobile malware as common mobile attack vectors and notes that mobile threats can steal personal and sensitive data from devices .

Option A. Call Spoofing is incorrect because the attack does not involve falsifying caller ID.

Option B. OTP Hijacking is incorrect because the scenario does not involve stealing one-time passwords.

Option C. SMiShing is incorrect because SMiShing requires a fraudulent text message designed to trick the user into clicking or responding. Here, no user interaction occurred.

Option D. SIMjacker is correct because invisible binary SMS messages triggered automatic device data transmission.

Therefore, the best answer is D. SIMjacker.