In a latest revelation by SEQRITE Labs, a extremely subtle cyber-espionage marketing campaign, dubbed Operation HollowQuill, has been uncovered.
The operation targets educational, governmental, and defense-related networks in Russia utilizing weaponized decoy PDFs to ship Cobalt Strike malware implants.
The marketing campaign seems to give attention to infiltrating important establishments such because the Baltic State Technical College (BSTU “VOENMEKH”) a key contributor to Russia’s military-industrial advanced.


Technical Exploitation Chain
The an infection chain begins with a malicious RAR archive containing a .NET-based malware dropper disguised as official analysis invites from the Ministry of Science and Increased Training of Russia.
This archive consists of a number of elements:
- A professional OneDrive executable.
- A Golang-based shellcode loader.
- A decoy PDF doc that serves as a lure for the focused entities.
Upon execution, the .NET dropper deploys the shellcode loader, injects malicious code into the OneDrive course of, and spawns the decoy PDF to keep away from suspicion.
The shellcode loader employs superior strategies equivalent to APC injection to execute the payload in reminiscence stealthily.
Decoy Doc Evaluation
The decoy PDF mimics official communication relating to state-assigned analysis initiatives for the 2026–2028 finances cycle.
It consists of detailed pointers for submitting proposals inside Russia’s Unified State Info System for Scientific Analysis and Technological Initiatives (ЕГИСУ НИОКТР).
Signed by high-ranking officers, together with A.E. Shashurin, performing rector of BSTU “VOENMEKH,” the doc enhances credibility and will increase the chance of person engagement.
The ultimate stage includes deploying a Cobalt Strike beacon a extensively used penetration testing instrument typically repurposed for malicious actions.
The beacon connects to a command-and-control (C2) server hosted on domains equivalent to phpsymfony[.]com.
It makes use of commonplace HTTP GET requests with encoded knowledge to speak covertly with the attacker infrastructure.
Key artifacts extracted from the shellcode reveal superior anti-analysis strategies, equivalent to time-based evasion mechanisms and reminiscence injection processes, making certain minimal detection by safety programs.


Evaluation of the marketing campaign’s infrastructure exhibits operational safety lapses by the attackers, together with uncovered Go construct IDs and rotating C2 domains throughout a number of ASN companies globally.
These identifiers have enabled researchers to hint related payloads and related malicious binaries distributed by different campaigns.
Operation HollowQuill highlights an alarming development in cyber warfare concentrating on important analysis and protection networks by subtle phishing ways and superior malware supply mechanisms.
By leveraging professional purposes like OneDrive and using in-memory execution strategies, the attackers have demonstrated a excessive stage of technical experience aimed toward evading detection whereas compromising delicate programs.
This marketing campaign underscores the necessity for sturdy cybersecurity measures throughout authorities and navy sectors to mitigate dangers posed by more and more subtle menace actors.
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