The Shadow Brokers, the group that has dumped many Windows exploits from NSA on the Web in April, has surfaced again, offering more exploits provided payment is made in Zcash.

A new exploit that is on offer is known as UNITEDRAKE. Details about this were made available in a PDF file which was part of the dump available on a site for download.

All of the files were encrypted and presumably decryptable by those who have obtained the necessary keys from the Shadow Brokers.

Two dumps were offered in the notice that was posted on Wednesday, one for 100 Zcash units, and the second for 200 units.

One of the exploits dumped by the Shadow Brokers, known as ETERNALBLUE, was used in crafting theransomware that devastated many companies in May.

And a second, known as ETERNALROMANCE, was used to craft ransomware that was given various names — Petya (nomenclature given to ransomware that already existed), NotPetya, ExPetr, Nyetya and GoldenEye — which attacked Windows machines in Europe in June and spread to other countries.

According to the PDF file, UNITEDRAKE is a system that both contains implants and the infrastructure used to operate remote implants with minimal operator interaction.

A target overview mentions FoxAcid which has been used to track Tor users in order to uncover the actual IPs which they are using.

Cryptography expert Bruce Schneier had this to say about FoxAcid: "After identifying an individual Tor user on the Internet, the NSA uses its network of secret Internet servers to redirect those users to another set of secret Internet servers, with the codename FoxAcid, to infect the user's computer. FoxAcid is an NSA system designed to act as a matchmaker between potential targets and attacks developed by the NSA, giving the agency opportunity to launch prepared attacks against their systems.

"Once the computer is successfully attacked, it secretly calls back to a FoxAcid server, which then performs additional attacks on the target computer to ensure that it remains compromised long-term, and continues to provide eavesdropping information back to the NSA."

A number of other details about UNITEDRAKE are listed in this rundown.

The Shadow Brokers first surfaced in August last year, offering for sale hacking tools which were said to have been pillaged from the Equation Group, an outfit which has long been suspected to have NSA links.

In January this year, the group offered a number of Windows exploits from the NSA for sale. It later dumped these exploits on the Web.