thinQmaster Virtual testing partner Adaptive practice exams that find your weak spots and drill them. Every answer explained. From $69
Enroll

thinQmaster

Find your exam

Five questions free, before you decide.

Step 1 · choose a vendor

In one of our camps? Your practice exams come with the tuition — they are on your study page already.

Security Operations · Intermediate

Replay Attack

Capturing valid data transmissions, such as authentication tokens, and retransmitting them to gain unauthorized access.

Definition

The attacker does not need to decrypt the data; replaying it is enough if the system does not check freshness. Defenses include timestamps, nonces, session tokens with short lifetimes, sequence numbers and protocols like Kerberos that include time-bound tickets.

Example

Replaying a captured key fob signal to unlock a car.

Exam tip

Nonces and timestamps are the standard anti-replay controls.

Don't confuse it with

Related terms