Reflector - Reflective DoS attacks
Reflection Denial of Service attacks makes use of a potentially legitimate third party component to send the attack traffic to a victim, ultimately hiding the attackers’ own identity. The attackers send packets to the reflector servers with a source IP address set to their victim’s IP therefore indirectly overwhelming the victim with the response packets.
The reflector servers used for this purpose could be ordinary servers not obviously compromised, which makes this kind of attack particularly difficult to mitigate. A common example for this type of attack is Reflective DNS Response attack.