New HiatusRAT Malware Targets Business-Grade Routers to Covertly Spy on Victims

Mar 06, 2023Ravie LakshmananNetwork Security / Malware

A never-before-seen complex malware is targeting business-grade
routers to covertly spy on victims in Latin America, Europe, and
North America at least since July 2022.

The elusive campaign, dubbed Hiatus by Lumen
Black Lotus Labs, has been found to deploy two malicious binaries,
a remote access trojan dubbed HiatusRAT and a variant of tcpdump^[1]
that makes it possible to capture packet capture on the target
device.

“Once a targeted system is infected, HiatusRAT allows the threat
actor to remotely interact with the system, and it utilizes
prebuilt functionality […] to convert the compromised machine
into a covert proxy for the threat actor,” the company said^[2]
in a report shared with The Hacker News.

“The packet-capture binary enables the actor to monitor router
traffic on ports associated with email and file-transfer
communications.”

The threat cluster primarily singles out end-of-life (EoL)
DrayTek Vigor router models 2960 and 3900, with approximately 100
internet-exposed devices compromised as of mid-February 2023. Some
of the impacted industry verticals include pharmaceuticals, IT
services/consulting firms, and municipal government, among
others.

Interestingly, this represents only a small fraction of the
4,100 DrayTek 2960 and 3900 routers that are publicly accessible
over the internet, raising the possibility that “the threat actor
is intentionally maintaining a minimal footprint to limit their
exposure.”

Given that the impacted devices are high-bandwidth routers that
can simultaneously support hundreds of VPN connections, it’s being
suspected that the goal is to spy on targets and establish a
stealthy proxy network.

“These devices typically live outside the traditional security
perimeter, which means they usually are not monitored or updated,”
Mark Dehus, director of threat intelligence for Lumen Black Lotus
Labs, said. “This helps the actor establish and maintain long-term
persistence without detection.”

The exact initial access vector used in the attacks is unknown,
but a successful breach is followed by the deployment of a bash
script that downloads and executes HiatusRAT and a packet-capture
binary.

HiatusRAT is feature-rich and can harvest router information,
running processes, and contact a remote server to fetch files or
run arbitrary commands. It’s also capable of proxying
command-and-control (C2) traffic through the router.

The use of compromised routers as proxy infrastructure is likely
an attempt to obfuscate the C2 operations, the researchers
said.

The findings come more than six months after Lumen Black Lotus
Labs also shed light on an unrelated router-focused malware
campaign that used a novel trojan called ZuoRAT^[4].

“The discovery of Hiatus confirms that actors are continuing to
pursue router exploitation,” Dehus said. “These campaigns
demonstrate the need to secure the router ecosystem, and routers
should be regularly monitored, rebooted, and updated, while
end-of-life devices should be replaced.”