Low-Budget Winter Vivern APT Awakens After 2-Year Hibernation

The underreported APT has returned to focus after attacks promoting Russian and Belarusian government interests and going after targets with humor, zest, and scrappiness.

A politically motivated cyber threat thats hardly discussed in the public sphere has made a sort of comeback in recent months, with campaigns against government agencies and individuals in Italy, India, Poland, and Ukraine.
Winter Vivern (aka UAC-0114) has been active since at least December 2020. Analysts tracked its initial activity in 2021, but the group has remained out of the public eye in the years since. That is, until attacks against Ukrainian and Polish government targets inspired reports on resurgent activity earlier this year from the
Central Cybercrime Bureau of Poland
, and the
State Cyber Protection Centre of the State Service of Special Communication and Information Protection of Ukraine
.
In a
follow-on analysis published this week
, Tom Hegel, senior threat researcher at SentinelOne, further elucidated the groups TTPs and emphasized its close alignment with global objectives that support the interests of Belarus and Russias governments, noting that it should be classified as an advanced persistent threat (APT) even though its resources arent on the par of its other Russian-speaking peers.
Winter Vivern, whose name is a derivative of the wyvern, a type of biped dragon with a poisonous, pointed tail falls into a category of scrappy threat actors, Hegel wrote. Theyre quite resourceful and able to accomplish a lot with potentially limited resources, while willing to be flexible and creative in their approach to problem solving.
The groups most defining characteristic is its phishing lures — usually documents mimicking legitimate and publicly available government literature, which drop a malicious payload upon being opened. More recently, the group has taken to mimicking government websites to distribute their nasties. Vivern has a sense of humor, mimicking homepages belonging to the primary cyber-defense agencies of Ukraine and Poland, as seen below.
The groups most tongue-in-cheek tactic, though, is to disguise its malware as antivirus software. Like their many other campaigns, the fake scanners are pitched through email to targets as government notices, Hegel tells Dark Reading.
These notices instruct recipients to scan their machines with this supposed antivirus software. Victims who download the fake software from the fake government domain will see what appears to be an actual antivirus running, when, in fact, a malicious payload is being downloaded in the background.
That payload, in recent months, has commonly been
Aperitif
, a Trojan that collects details about victims, establishes persistence on a target machine, and beacons out to an attacker-controlled command-and-control server (C2).
The group employs many other tactics and techniques, too. In a recent campaign against Ukraines
I Want to Live
hotline, they resorted to an old favorite: a macro-enabled Microsoft Excel file.
And when the threat actor seeks to compromise the organization beyond the theft of legitimate credentials, Hegel wrote in his post, Winter Vivern tends to rely on shared toolkits and the abuse of legitimate Windows tools.
The Winter Vivern story is scattershot and leads to a somewhat confused profile.
Its targets are pure APT: Early in 2021, researchers from
DomainTools were parsing Microsoft Excel documents
using macros when they came upon one with a rather innocuous name: contacts. The contacts macro dropped a PowerShell script that contacted a domain thatd been active since December 2020. Upon further investigation, the researchers discovered more than theyd bargained for: other malicious documents targeting entities within Azerbaijan, Cyprus, India, Italy, Lithuania, Ukraine, and even the Vatican.
The group was clearly still active by the summertime, when
Lab52 published news of an ongoing campaign
matching the same profile. But it wasnt until January 2023 that it resurfaced in the public eye, following campaigns against individual members of the Indian government, the Ukraine Ministry of Foreign Affairs, the Italy Ministry of Foreign Affairs, and other European government agencies.
Of particular interest, Hegel noted in his blog post, is the APTs targeting of private businesses, including telecommunications organizations that support Ukraine in the ongoing war.
This special emphasis on Ukraine adds intrigue to the story since, as recently as February, the Ukraine government was only able to conclude with a high level of confidence that Russian-speaking members are present within the group. Hegel has now gone a step further, by directly correlating the group with Russian and Belarusian state interests.
With the potential ties into Belarus, its challenging to determine if this is a new organization or simply new tasking from those we know well, Hegel tells Dark Reading.
Even so, the group doesnt fit the profile of a typical nation-state APT. Their lack of resources, their scrappiness — relative to their heavy-hitting counterparts like
Sandworm
,
Cozy Bear
,
Turla
, and others — place them in a category nearer to more ordinary hacktivism. They do possess technical skills to accomplish initial access, however, at this time they dont stack up to highly novel Russian actors, Hegel says.
Beyond the limited capacities, their very limited set of activity and targeting is why they are so unknown in the public, Hegel says. It may be in Winter Viverns favor, in the end. So long as it lacks that extra bite, it may continue to fly under the radar.

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Low-Budget Winter Vivern APT Awakens After 2-Year Hibernation