Cisco Talos has uncovered an ongoing cyber marketing campaign by the Gamaredon risk actor group, focusing on Ukrainian customers with malicious LNK information to ship the Remcos backdoor.
Energetic since no less than November 2024, this marketing campaign employs spear-phishing techniques, leveraging themes associated to the Ukraine battle to lure victims into executing the malicious information.
The LNK information, disguised as Workplace paperwork, are distributed inside ZIP archives and carry filenames referencing troop actions and different war-related matters in Russian or Ukrainian.
The assault begins with the execution of a PowerShell downloader embedded in the LNK file.
This downloader contacts geo-fenced servers situated in Russia and Germany to retrieve a second-stage ZIP payload containing the Remcos backdoor.
The downloaded payload employs DLL sideloading methods to execute the backdoor, a technique that includes loading malicious DLLs via official purposes. This strategy permits attackers to bypass conventional detection mechanisms.
Refined Supply Mechanisms
Gamaredon’s phishing emails doubtless embrace both direct attachments of the ZIP information or URLs redirecting victims to obtain them.
The marketing campaign’s filenames, corresponding to “Coordinates of enemy takeoffs for 8 days” or “Positions of the enemy west and southwest,” recommend a deliberate try to use delicate geopolitical themes.
Metadata evaluation signifies that solely two machines have been used to create these malicious shortcut information, in keeping with Gamaredon’s operational patterns noticed in earlier campaigns.
The PowerShell scripts embedded within the LNK information use obfuscation methods, corresponding to leveraging the Get-Command cmdlet, to evade antivirus detection. As soon as executed, these scripts obtain and extract the ZIP payload into the %TEMP% folder.
The payload consists of clear binaries that load malicious DLLs, which decrypt and execute the ultimate Remcos backdoor payload.
This backdoor is injected into Explorer.exe and communicates with command-and-control (C2) servers hosted on infrastructure based totally in Germany and Russia.
Focused Infrastructure and Indicators of Compromise
The marketing campaign’s C2 servers are hosted by Web Service Suppliers corresponding to GTHost and HyperHosting.
Notably, Gamaredon restricts entry to those servers primarily based on geographic location, limiting them to Ukrainian victims.
Reverse DNS information for a few of these servers reveal distinctive artifacts which have helped researchers establish further IP addresses related to this operation.
The Remcos backdoor itself offers attackers with sturdy capabilities for distant management, together with knowledge exfiltration and system manipulation.
Cisco Talos has noticed proof of fresh purposes like TivoDiag.exe being abused for DLL sideloading throughout this marketing campaign.
Gamaredon’s use of superior methods corresponding to DLL sideloading, geo-fenced infrastructure, and thematic phishing underscores its persistence in focusing on Ukraine amidst ongoing geopolitical tensions.
Organizations are suggested to stay vigilant in opposition to such threats by implementing sturdy endpoint safety, electronic mail safety measures, and community monitoring options.
IOCs for this risk may be present in our GitHub repository right here.
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