Backdoor infecting VPNs used “magic packets” for stealth and security

When threat actors use backdoor malware to gain access to a network, they want to make sure all their hard work can’t be leveraged by competing groups or detected by defenders. One countermeasure is to equip the backdoor with a passive agent that remains dormant until it receives what’s known in the business as a “magic packet.” On Thursday, researchers revealed that a never-before-seen backdoor that quietly took hold of dozens of enterprise VPNs running Juniper Network’s Junos OS has been doing just that.

J-Magic, the tracking name for the backdoor, goes one step further to prevent unauthorized access. After receiving a magic packet hidden in the normal flow of TCP traffic, it relays a challenge to the device that sent it. The challenge comes in the form of a string of text that’s encrypted using the public portion of an RSA key. The initiating party ...