Spies hack Wi-Fi networks in far-off land to launch attack on target next door

One of 2024's coolest hacking tales occurred two years ago, but it wasn't revealed to the public until Friday at the Cyberwarcon conference in Arlington, Virginia. Hackers with ties to Fancy Bear—the spy agency operated by Russia’s GRU—broke into the network of a high-value target after first compromising a Wi-Fi-enabled device in a nearby building and using it to exploit compromised accounts on the target’s Wi-Fi network.

The attack, from a group security firm Volexity calls GruesomeLarch, shows the boundless lengths well-resourced hackers will take to hack high-value targets, presumably only after earlier hack attempts haven’t worked. When the GruesomeLarch cabal couldn’t get into the target network using easier methods, they hacked a Wi-Fi-enabled device in a nearby building and used it to breach the target’s network next door. After the first neighbor’s network was disinfected, the hackers successfully performed the same attack on a device of a second neighbor.

Too close for comfort

“This is a fascinating attack where a foreign adversary essentially conducted a close access operation while being physically quite far away,” Steven Adair, a researcher and the president of Volexity, wrote in an email. “They were able to launch an attack that historically had required being in close proximity to the target but found a way to conduct it in a way which completely eliminated the risk of them being caught in the real world.”

While stalking its target, GruesomeLarch performed credential-stuffing attacks that compromised the passwords of several accounts on a web service platform used by the organization's employees. Two-factor authentication enforced on the platform, however, prevented the attackers from compromising the accounts.

So GruesomeLarch found devices in physically adjacent locations, compromised them, and used them to probe the target’s Wi-Fi network. It turned out credentials for the compromised web services accounts also worked for accounts on the Wi-Fi network, only no 2FA was required.

Adding further flourish, the attackers hacked one of the neighboring Wi-Fi-enabled devices by exploiting what in early 2022 was a zero-day vulnerability in the Microsoft Windows Print Spooler.

The 2022 hack demonstrates how a single faulty assumption can undo an otherwise effective defense. For whatever reason—likely an assumption that 2FA on the Wi-Fi network was unnecessary because attacks required close proximity—the target deployed 2FA on the Internet-connecting web services platform (Adair isn’t saying what type) but not on the Wi-Fi network. That one oversight ultimately torpedoed a robust security practice.

Advanced persistent threat groups like GruesomeLarch—a part of the much larger GRU APT with names including Fancy Bear, APT28, Forrest Blizzard, and Sofacy—excel in finding and exploiting these sorts of oversights.

Volexity’s post describing the 2022 attack provides plenty of technical details about the compromise on the many links in this sophisticated daisy chain attack flow. There’s also useful advice for protecting networks against these sorts of compromises.