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A Silent Cyber War Escalates as Gamaredon Expands Malware Arsenal Against Ukraine
Introduction
The cyber battlefield surrounding the Russia-Ukraine conflict has entered another dangerous phase. While missiles and drones dominate international headlines, an equally destructive war continues behind computer screens, targeting government institutions, military networks, and critical infrastructure. Throughout 2025, one of Russia’s most persistent cyber espionage groups significantly expanded both its operational reach and technical capabilities, demonstrating that cyber warfare has become an indispensable weapon in modern geopolitical conflicts.
A new analysis published by cybersecurity researchers at ESET reveals that the Gamaredon advanced persistent threat (APT) group remained relentlessly focused on Ukraine during 2025. Instead of relying on sophisticated zero-day exploits alone, the group refined its long-standing strategy of persistence, rapid malware evolution, and abuse of trusted online services, making detection and disruption increasingly difficult.
Gamaredon Intensifies Operations Throughout 2025
According to ESET researchers, Gamaredon launched at least 35 separate spear-phishing campaigns during 2025, with activity accelerating considerably during the latter half of the year.
The overwhelming majority of attacks targeted Ukrainian governmental agencies, military organizations, and institutions involved in national defense. Unlike financially motivated cybercriminals, Gamaredon’s objectives remain centered on intelligence gathering and long-term espionage.
Researchers believe the
Spear Phishing Remains the Primary Entry Point
Rather than abandoning proven attack techniques, Gamaredon has continued improving its phishing infrastructure.
Victims typically receive malicious archive attachments or specially crafted XHTML documents. These files leverage HTML smuggling techniques to secretly deliver malicious HTA downloaders without immediately triggering security protections.
Once executed, the downloader installs additional malware payloads, including the increasingly observed PteroSand family.
This layered infection process enables attackers to deploy new malware components whenever necessary while keeping the initial infection relatively lightweight and difficult to detect.
WinRAR Vulnerability Added Another Infection Vector
One notable evolution observed during 2025 involves exploitation of the patched WinRAR vulnerability tracked as CVE-2025-8088.
Instead of simply executing malware immediately, attackers abuse the vulnerability to silently place malicious HTA downloaders inside the Windows Startup folder.
This provides automatic execution every time the infected user logs back into Windows.
Persistence has always been one of
USB Devices Continue to Serve as Malware Carriers
Gamaredon has never relied exclusively on internet-connected attacks.
Several malware weaponizers remain focused on spreading through removable media and internal organizational networks.
PteroLNK and PteroPaste continue infecting USB drives and mapped network folders by replacing legitimate shortcuts with malicious LNK files.
Whenever an unsuspecting employee opens one of these shortcuts, additional downloader malware is retrieved from attacker-controlled infrastructure.
This allows infections to spread inside isolated or partially disconnected environments where internet access may be limited.
PteroSetup Returns Despite Earlier Assumptions
Researchers also observed the return of PteroSetup, an older Visual Basic Script-based tool first identified in 2021.
Many analysts believed this malware component had been retired.
Instead, Gamaredon quietly modernized its functionality.
The malware searches USB devices and mapped network drives for legitimate software installers before replacing them with self-extracting 7z archives.
Victims unknowingly execute what appears to be a legitimate installer while simultaneously launching a hidden VBScript downloader.
The original application still installs successfully, reducing user suspicion and increasing infection success rates.
Six New Malware Tools Expand
One of the most significant discoveries involves six newly identified PowerShell-based malware components that considerably increase Gamaredon’s operational flexibility.
PteroDee and PteroCache specialize in downloading and executing PowerShell payloads directly in system memory.
PteroDum performs similar functions but targets VBScript payloads instead.
PteroOdd retrieves PowerShell payloads using the Telegra.ph API and may have been used during operations involving cooperation with the Russian threat actor Turla.
PteroEffigy locates command-and-control servers through GoFile cloud storage.
PteroPaste continues evolving into a multifunctional framework capable of infecting USB devices while securely retrieving encrypted PowerShell payloads.
Collectively, these tools allow Gamaredon to rapidly adapt attack chains without deploying large standalone malware families.
Legitimate Cloud Services Become Cyber Weapons
Perhaps the most concerning trend is
Rather than maintaining traditional attacker-controlled servers that defenders can quickly identify and block, the group increasingly hides infrastructure behind legitimate online platforms.
Researchers documented abuse of numerous widely used services, including:
Telegra.ph
Teletype
Rentry
Write.as
Dropbox
GoFile
DEV Community
Mastodon
Lesma
Nopaste.net
Paste.ee
Wasabi Cloud Storage
Tebi
Intercolo
These platforms function as dead drops, encrypted communication channels, cloud storage repositories, or infrastructure discovery mechanisms.
Because organizations often trust these legitimate services, blocking malicious traffic becomes significantly more difficult without disrupting normal business operations.
Tunnel Services and Serverless Infrastructure Increase Stealth
Another major shift during 2025 involved heavy adoption of tunnel services and serverless worker platforms.
Instead of exposing command-and-control servers directly to the internet, Gamaredon increasingly routed communications through intermediary infrastructure.
This approach conceals the true backend location while allowing operators to rotate servers quickly whenever defenders identify malicious infrastructure.
Combined with dynamic DNS services and cloud-hosted resources, the architecture becomes substantially more resilient against traditional takedown operations.
Operational Patterns Suggest Government Affiliation
Researchers also noticed an interesting operational rhythm.
Gamaredon’s development activity temporarily slowed during January before accelerating throughout the first half of the year.
Large batches of malware updates frequently appeared immediately before major Russian and Crimean holidays.
Conversely, almost no development activity occurred during or immediately after those holidays.
Although this does not independently prove attribution, the consistency of these working patterns aligns with previous assessments suggesting that Gamaredon operators may function as government-affiliated personnel rather than ordinary cybercriminals.
Persistence Continues to Outperform Sophistication
Gamaredon has rarely relied on cutting-edge malware engineering.
Instead, the
Campaigns evolve continuously.
Infrastructure changes frequently.
Malware receives constant updates.
Attack chains are rebuilt whenever defenders identify them.
By combining relatively simple malware with operational discipline, Gamaredon remains one of the most effective cyber espionage groups operating against Ukraine despite years of exposure by international security researchers.
Deep Analysis: Linux Defensive Commands for Malware Investigation
Modern defenders should assume that phishing campaigns targeting Windows environments may eventually impact Linux-based security infrastructure as well. Security analysts can use several Linux utilities to investigate suspicious artifacts and monitor compromised environments.
sha256sum suspicious_file.exe
file suspicious_file.exe
strings suspicious_file.exe
hexdump -C suspicious_file.exe
xxd suspicious_file.exe
clamscan suspicious_file.exe
yara malware_rules.yar suspicious_file.exe
tcpdump -i eth0
ss -tunap
netstat -plant
lsof -i
journalctl -xe
last
lastlog
who
w
ps aux
pstree
systemctl list-units
find / -perm -4000
find /tmp -type f
find /var/tmp -type f
crontab -l
cat /etc/crontab
lsmod
modinfo
ip addr
ip route
iptables -L
nft list ruleset
dig
host
nslookup
curl
wget
openssl x509
grep -Ri suspicious /etc
chmod
chattr
auditctl -l
ausearch
rkhunter --check
chkrootkit
These commands assist investigators in examining suspicious binaries, identifying persistence mechanisms, analyzing network traffic, auditing authentication logs, monitoring scheduled tasks, detecting privilege escalation, inspecting firewall rules, validating certificates, and searching for indicators of compromise. When combined with endpoint detection platforms, YARA rules, and threat intelligence feeds, they provide a strong foundation for incident response and forensic investigations against advanced persistent threats.
What Undercode Say:
Gamaredon represents an excellent example of how persistence often defeats sophistication in long-term cyber espionage. Unlike many modern ransomware groups seeking immediate financial gain, Gamaredon’s operations demonstrate patience measured in months rather than hours.
The most significant technical evolution is not the malware itself but the infrastructure supporting it.
Abusing legitimate cloud providers dramatically shifts the defensive challenge.
Organizations cannot simply block Dropbox or Mastodon without affecting legitimate business processes.
The migration toward serverless workers reflects a broader industry trend where attackers increasingly leverage cloud-native architectures.
Infrastructure now becomes disposable.
Every exposed server can be replaced within minutes.
The return of older malware like PteroSetup also highlights an important reality.
Threat actors rarely abandon useful tools permanently.
Older malware frequently returns after extensive modification.
Security teams focusing only on newly discovered malware families risk overlooking recycled attack components.
Gamaredon’s extensive use of PowerShell indicates continued reliance on “living off the land” techniques.
Rather than dropping massive executable payloads, attackers increasingly exploit native operating system capabilities.
Memory-only execution significantly complicates forensic investigations.
Traditional antivirus products remain less effective against in-memory malware execution than against conventional executable files.
The operational timing around Russian holidays deserves attention.
Although scheduling patterns alone cannot conclusively prove state sponsorship, repeated observations strengthen attribution confidence when combined with intelligence from other sources.
The increasing diversity of dead-drop services reveals another strategic shift.
Instead of depending on one communication platform, Gamaredon distributes operational risk across numerous providers.
Disrupting one service has minimal operational impact.
Future campaigns will likely become even more decentralized.
Artificial intelligence may soon assist attackers in generating phishing lures tailored to specific government employees.
Cloud infrastructure abuse will probably expand further.
Identity theft rather than malware deployment may become the preferred initial access technique.
Organizations defending against state-sponsored actors should prioritize behavioral detection instead of signature-based security.
Continuous threat hunting has become essential.
Zero Trust architectures reduce lateral movement opportunities.
Hardware-backed authentication significantly decreases phishing success.
Employee awareness remains one of the strongest defensive investments.
Rapid vulnerability management continues to close many attacker opportunities.
Incident response exercises should simulate cloud-based command-and-control infrastructure.
USB device monitoring deserves renewed attention.
PowerShell logging should remain enabled whenever operationally possible.
Centralized log correlation becomes increasingly valuable.
Threat intelligence sharing across allied organizations accelerates defensive adaptation.
Security teams should expect frequent infrastructure rotation.
Persistence mechanisms require continuous auditing.
Backup systems must remain isolated from operational networks.
Cyber resilience now matters as much as cyber prevention.
The conflict in Ukraine continues demonstrating that cyber warfare is no longer a supporting capability.
It has become an operational domain equal to land, air, sea, and space.
✅ ESET documented
✅ The report confirms expanded use of legitimate cloud platforms, tunnel services, dead-drop infrastructure, and PowerShell-based malware to improve operational resilience and reduce detection.
✅ While many intelligence agencies associate Gamaredon with Russian state interests, direct government control remains an attribution assessment rather than publicly proven legal fact, making the researchers’ wording appropriately cautious.
Prediction
(+1) Defensive technologies focused on behavioral analytics, Zero Trust security, and cloud telemetry will become increasingly effective at detecting Gamaredon’s evolving infrastructure.
(-1) Threat actors will continue abusing legitimate cloud services, AI-assisted phishing, and memory-resident malware, making future espionage campaigns even harder to attribute, detect, and disrupt.
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References:
Reported By: thehackernews.com
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