On November 15, 2005 vnunet.com announced that Sony BMG was backing out of its copy-protection software, recalling unsold CDs from all stores, and offering consumers to exchange their CDs with versions lacking the software. The Electronic Frontier Foundation compiled a partial list of CDs with XCP. Sony BMG was quoted as maintaining that "there were no security risks associated with the anti-piracy technology", despite numerous virus and malware reports. On November 16, 2005, US-CERT, part of the United States Department of Homeland Security, issued an advisory on XCP DRM. They said that XCP uses rootkit technology to hide certain files from the computer user and that this technique is a security threat to computer users. They also said one of the uninstallation options provided by Sony BMG introduces further vulnerabilities to a system. US-CERT advised, "Do not install software from sources that you do not expect to contain software, such as an audio CD."