They were highly popular objects for deatheaters to hide in when the danger had passed. Hermione thought about relaying this information to Harry and Ron but thought better of it. She did not want to involve them in something that would get them into trouble, no doubt, Harry would want to act on this information and try to catch Malfoy out. Though, Hermione admitted, she felt the overwhelming desire to do the same, just to see what Malfoy was doing with the cabinet. Hermione supposed there was another cabinet at Hogwarts and recited the purpose of the cabinet from the book in her mind. She remembered that no one could apparate within the Hogwarts grounds, so she guessed that Draco was planning to escape the castle through that cabinet to end up in Borgin & Burkes, but for what?