This looks familiar to me:

As with previous seizures, ICE convinced a District Court judge to sign a seizure warrant, and then contacted the domain registries to point the domains in question to a server that hosts the warning message. However, somewhere in this process a mistake was made and as a result the domain of a large DNS service provider was seized.

The domain in question is mooo.com, which belongs to the DNS provider FreeDNS. It is the most popular shared domain at afraid.org and as a result of the authorities’ actions a massive 84,000 subdomains were wrongfully seized as well. All sites were redirected to the banner below.

…

A noble initiative, but one that went wrong, badly. The above failure again shows that the seizure process is a flawed one, as has been shown several times before in earlier copyright infringement sweeps. If the Government would only allow for due process to take place, this and other mistakes wouldn’t have been made.

Via https://torrentfreak.com/u-s-government-shuts-down-84000-websites-by-mistake-110216/.

See also https://www.dhs.gov/ynews/releases/pr_1297804574965.shtm.