WikiLeaks, continuing its data dump of leaked CIA hacking tools, released a set of documents on Thursday that appear to show how the agency was able to spy on Apple's Mac computers and iPhones.

Most of the leaked documents describe hacking methods that are several years old, which suggests they may have been updated or retired as new Apple products were released. With code names like "Dark Matter" and "Sonic Screwdriver," the hacking tools could have allowed the CIA to gain access to computers and mobile devices using techniques like installing malware in a device's firmware, according to WikiLeaks.

Among the documents is a user guide from 2012 for the Sonic Screwdriver tool, which describes the CIA's attempts to execute code on peripheral devices while a Mac desktop or laptop is booting up. The technique is familiar to anyone who has experience changing their PC's boot drive: the CIA's implant code was stored on an Apple Thunderbolt-to-Ethernet adapter, and it scanned all external and internal bootable drives to find one that would let it install a surveillance backdoor on bootup.

Once the backdoor was installed and the computer rebooted into macOS, the infected Ethernet adapter would function normally. The CIA tested the tool on many MacBook models introduced starting in 2011, according to the user guide.

Another leaked document describes the "NightSkies" tool from 2008, which was designed to be physically installed onto factory fresh iPhones. That suggests the CIA had access to the iPhone supply chain, according to WikiLeaks.

The documents released on Thursday are part of the "Vault 7" trove of leaked CIA hacking tools, which WikiLeaks first announced on March 7. The organization claims the trove is the largest-ever publication of confidential CIA documents, and it said it would give the manufacturers of the targeted software and hardware time to address the vulnerabilities described in the documents before releasing them.

WikiLeaks has reportedly been slow to fulfill that promise, however, requiring demands from companies before it hands over the data, according to Vice News. It was not immediately clear whether Apple had time to review the documents leaked on Thursday.