When set up properly, modern computer networks are actually very hard to hack. That's why hackers have learned to avoid the direct approach, such as guessing passwords, and come at the problem from another direction.
One way they like to attack is by using phishing scams to trick critical information out of employees who use the network, or to get them to download viruses. With a well-crafted phishing attack, a hacker can get full access to anything they want. However, there's another way around network defenses, and that's creating a backdoor in the network hardware itself.
That's what seems to have happened at Juniper Networks, a company that makes high-end network hardware for the U.S. government and major businesses. While doing a routine review of its hardware recently, Juniper discovered that someone managed to install code on its hardware that would give a hacker full access to secure networks. That includes snooping on attached gadgets and reading encrypted messages.
It's bad enough when Juniper clients include the Defense Department, Justice Department, FBI and Treasury Department. However, it gets worse because Juniper says the code has been in place for three years. That means hackers could have gotten tons of confidential information from the government and major companies. It makes you wonder how often its "routine reviews" are.
The FBI is conducting an investigation and believes the party responsible is a foreign government. U.S. officials have said it definitely wasn't a U.S. agency behind the backdoor, which you may or may not choose to believe given the revelations of the last few years.
Juniper has released a patch to close the backdoor and is urging its clients to install it. It is also quick to point out that it has seen no evidence of the backdoor being used, although it reluctantly admits that any hackers using the backdoor could easily cover their tracks.