The vulnerability mentioned above allows an attacker to open thousands of connections to the attacked site in the darkweb and leave them “hanging”. For each connection, the Onion service that supports the operation of the site must establish a communication channel in the Tor network, which will ensure the protection of information transmitted from the user to the server and back. This procedure has a significant load on the server processor, and the simultaneous opening of a large number of connections can bring it up to 100%, as a result of which the server will refuse to accept new ones.
Tor Project will fix a bug that has been used for years to destroy sites on the darknet
There are several different sets of tools available on the Internet to exploit this vulnerability, including absolutely free ones. For example, the Stinger-Tor program written in Python has been freely available on the hosting of IT projects on Github for about four years. Commercial software for DDoS on Onion services, as noted by ZDNet, can be found on the forums on the darknet.