A pingback is one of four types of linkback methods for Web authors to request notification when somebody links to one of their documents.
The Pingback specification was developed in 2002 by Stuart Langridge, Simon Willison, and Ian Hickson.
[1][2][3][4][5] In March 2014, Akamai published a report about a widely seen exploit involving pingback that targets vulnerable WordPress sites.
[6] This exploit led to massive abuse of legitimate blogs and websites and turned them into unwilling participants in a DDoS attack.
[11] Notwithstanding, in 2016, pingback attacks continued to exist, supposedly because the website owners don't check the user agent logs, that have the real IP addresses.