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Elizabeth Montalbano , Contributing Writer May 14, 2026 4 Min Read Source: Piotr Malczyk via Alamy Stock Photo A known Belarussian cyberespionage group is back with a threat campaign against targets in Eastern Europe that uses spearphishing to deliver malicious payloads to Eastern European government and military organizations. The campaign is unique in that the group appears to be particularly choosy about who it targets. In a campaign that began in March and targets entities in Poland and Ukraine specifically, FrostyNeighbor — also tracked as Ghostwriter , UNC1151, TA445, PUSHCHA, and Storm-0257 — demonstrates a continued evolution of its cybercriminal activities on behalf of Belarus, according to a report by ESET research published Thursday. Its latest attack wave targets Ukrainian and Polish government organizations, and demonstrates how the group is continuing to evolve its espionage toolkit and delivery infrastructure, according to ESET. The advanced persistent threat (APT) is using a fresh compromise chain with spear-phishing PDFs, server-side victim validation, and a JavaScript-based version of PicassoLoader, the group's main payload downloader, to ultimately deploy Cobalt Strike for post-compromise operations. Related: Foxconn Attack Highlights Manufacturing's Cyber Crisis "Since January 2026, the group seems to have abandoned the use of macro-based initial lure document ... to only use blurry PDFs containing a malicious link to the next stage," Damien Schaeffer, ESET senior malware researcher, tells Dark Reading. That PDF lure impersonates Ukrainian telecom provider Ukrtelecom, and claims to provide secure customer data protection. It includes a download link hosted on attacker-controlled infrastructure. FrostNeighbor's Cyber Evolution Beyond Disinformation FrostyNeighbor, believed to be active since at least 2016, is known for combining cyberespionage with other malicious operations, including spearphishing, credential theft, malware deployment, and disinformation activity associated with the broader Ghostwriter influence operation . That campaign — which began in 2021 and was first believed to be out of Russia — targeted several European countries, including Germany, Poland, Ukraine, and the Baltic states of Estonia, Latvia, and Lithuania, with phishing and misinformation. Eventually, researchers discovered that Ghostwriter/FrostyNeighbor had a more significant phishing infrastructure than first known, which figures prominently in its latest attack. The latest iteration is highly targeted, with attackers fingerprinting the victim's computer to ensure targeting is specific. While this in an of itself is not unique, FrostyNeighbor operators appear to then be deciding manually whether or not the target will get the implant or not, Schaeffer says. Related: China's 'FamousSparrow' APT Nests in South Caucasus Energy Firm FrostyNeighbor's Manual, Specific Victim-Targeting If the victim is not from the expected geographic location, the server delivers a benign PDF file. However, if the victim is using an IP address from Ukraine , the server instead delivers a RAR archive containing the first stage of the attack — a JavaScript file that drops and displays the aforementioned PDF file as a decoy. Simultaneously, it also executes the second stage: a JavaScript version of the PicassoLoader downloader . When running, PicassoLoader fingerprints the victim’s computer by collecting the username, computer name, OS version, the boot time of the computer, the current time, and the list of running processes with their process IDs. The decision whether or not to deliver a payload is very likely manually performed by the operators, as mentioned before, based on the collected information to decide if the victim is of interest, according to ESET. If they are, command-and-control (C2) responds with a third-stage JavaScript dropper for Cobalt Strike , the final payload; otherwise, it returns an empty response. Defensive, Anti-Espionage Action for Eastern European Targets Related: Tech Can't Stop These Threats — Your People Can FrostyNeighbor remains "quite active in term of operations, and has demonstrated a continued evolution in its TTPs, trying new techniques to evade detections and compromise its targets," Schaeffer says. Indeed, the newest compromise chain outlined in the report is a continuation of the group’s persistent willingness to update and renew its arsenal, according to ESET. For this reason, organizations that could be targeted by the group — especially in Poland, Lithuania, and Ukraine — should take defensive measures. These include taking the usual spear-phishing precautions, such as carefully analyzing emails with an attachment coming from external or unknown senders, Schaeffer says. Defenders also can implement best practices such as restricting user permissions to the minimum, or preventing execution of downloaded files, and monitoring its users and environment for suspicious network communications, he adds. To help defenders identify the campaign, ESET also included a comprehensive list of indicators of compromise (IoCs) in its report. About the Author Elizabeth Montalbano Contributing Writer Elizabeth Montalbano is a freelance writer, journalist, and therapeutic writing mentor with more than 25 years of professional experience. Her areas of expertise include technology, business, and culture. Elizabeth previously lived and worked as a full-time journalist in Phoenix, San Francisco, and New York City; she currently resides in a village on the southwest coast of Portugal. In her free time, she enjoys surfing, hiking with her dogs, traveling, playing music, yoga, and cooking. See more from Elizabeth Montalbano Want more Dark Reading stories in your Google search results? Add Us Now More Insights Industry Reports How Enterprises Are Developing Secure Applications Inside RSAC 2026: security leaders reveal the risks redefining your defense strategy How Enterprises Are Harnessing Emerging Technologies in Cybersecurity Ditch the Data Center: Understanding Flexible Cloud Infrastructure Security Management 2025 State of Malware Access More Research Webinars Your Guide to Securing AI Adoption in Your Organization What is the Right Role for Identity Threat Detection and Response (ITDR) in Your Organization? 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