It appears that the NSA (“or someone”) hacked into the code of a popular firewall and planted a password in there that would allow them access as needed.
That means the NSA (“or someone”) would be able to bypass the security features of a network and do what they wanted inside. This is basically an act of sabotage. Given that American organizations as well as foreign ones use these same firewalls, and that the planted password could be discovered by others outside the NSA, the act made vulnerable a multitude of innocent, untargeted systems.
Juniper Networks makes a popular line of enterprise firewalls whose operating system is called Screen OS. The company raised alarm bells with an advisory announcing that they’d discovered “unauthorized code” in some versions of Screen OS, a strange occurrence that hinted that a security agency had managed to tamper with the product before it shipped. One possible route would be for any such agency to have its own people inside the company, acting under cover.
An investigator for Juniper reported that he and his team have confirmed that the “unauthorized code” is a backdoor whose secret password enables the wielder to telnet or ssh into Juniper’s appliances. The password is <<< %s(un=’%s’) = %u, “presumably chosen so that it would be mistaken for one of the many other debug format strings in the code.” Further investigation located 26,000 Juniper devices that are vulnerable to this attack until patched.