An attacker sits between customer and Banker, and captures the information…

Security attacks are grouped into passive attacks — pure eavesdropping or traffic analysis, with no interference — and active attacks, which interfere with data in transit. The standard active-attack taxonomy names four mechanisms: Masquerade (faking an identity to gain access), Replay (capturing a genuine transmission and retransmitting it to the intended recipient), Modification of messages (altering captured content before it is delivered), and Denial of Service (disrupting availability).

Here the attacker sits inline between the customer and the banker, captures the customer's message, and sends an altered version on to the banker — that is, it captures a real transmission and retransmits it to the intended recipient. That capture-then-retransmit mechanism is what the Replay Attack option names, and published PYQ-answer sources independently key this exact question to Replay Attack.

Strictly speaking, a textbook replay attack forwards the same captured data unchanged, while altering the content first is more precisely called a modification-of-message (or man-in-the-middle) attack — so the underlying concern behind this question's report is technically valid. However, “Modification of message” is not one of the four options offered here, and among Masquerade, Replay, Passive, and Denial of Service, Replay Attack remains the closest match and the option that published PYQ sources key as correct for this question, since it alone captures the capture-then-retransmit-to-the-intended-party mechanism.

• Masquerade Attack: works by adopting a false identity to interact directly with the target; it does not depend on first intercepting a message that two other genuine parties exchanged.

• Passive Attack: confined to silent observation of traffic; it never sends anything on to the intended recipient afterward.

• Denial of Service Attack: targets the availability of a service by overwhelming or disabling it; it has no notion of intercepting or forwarding any specific message.