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UAC-0099 is a Russia-aligned threat cluster active since at least mid-2022 that primarily targets Ukrainian organizations, including entities in the transportation and energy sectors. The group conducts phishing-led initial-access operations and has been linked to providing validated access to GRU-linked Sandworm (APT44) operators for follow-on activity. UAC-0099 has used phishing lures, archive-delivered scripts disguised as documents, and exploitation of WinRAR vulnerabilities to deliver malware including LONEPAGE, MATCHBOIL, MATCHWOK, and DRAGSTARE. In 2026, UAC-0099 used a trojanized Notepad++ plugin-loading chain to deploy LUNCHPOKE, BURNYBEAR, and MATCHBOIL.V2. The operation abused legitimate application plugin behavior to load a malicious DLL, established scheduled-task persistence, and used the MATCHBOIL loader to update command-and-control configuration and retrieve further payloads. BURNYBEAR includes resource-exhaustion behavior that can consume CPU and memory when run without expected arguments, likely complicating automated analysis. UAC-0099 also used the GuardBreaker anti-analysis technique: safety-sensitive natural-language content was embedded in comments in a malicious VBScript in an effort to trigger LLM safety refusals and disrupt AI-assisted malware inspection. The same script performed conventional anti-analysis checks and was designed to download and install MATCHBOIL. The actor's documented operations demonstrate phishing-based initial access, defense evasion through masquerading and anti-analysis measures, plugin-based DLL sideloading, persistence, and staged payload delivery.
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Who, where, and (when attributed) which flag flies behind the operation. Pulled from open-source reporting and Mallory's analyst review.
Sectors the actor has been observed targeting.
Geographies tied to known operations.
Attributed origin per open-source reporting.
29 distinct techniques observed across reporting, grouped by tactic. Hover any cell for the evidence excerpt; click through for MITRE's full description.
9 malware families attributed to this actor across reporting.
4 additional families tracked in Mallory.
1 CVE this actor has used in observed campaigns. 1 of them exploited in the wild.
68 indicators attributed to this actor: domains, IPs, hashes, and other artifacts pulled from reporting. View more in app.
20 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Russia-aligned activity cluster using a GuardBreaker prompt-injection technique: embedding safety-sensitive text in a VBScript comment to induce AI code-analysis tools to refuse or abandon analysis. The script downloads and installs the MATCHBOIL loader; the group has also used phishing-led delivery and includes checks for analysis tools such as IDA and Wireshark.
Russia-aligned UAC-0099 used a VBScript downloader for the MATCHBOIL loader in an early-stage intrusion against a Ukrainian target. The group embedded a policy-triggering prompt in a script comment—a technique termed GuardBreaker—to cause AI-assisted code scanners to refuse or halt analysis, creating an evasion blind spot.
Conducted an early-stage attack against a Ukrainian target using a VBScript downloader/installer for the MATCHBOIL loader. The group used the GuardBreaker technique—an LLM guardrail-triggering comment intended to halt AI-assisted malware analysis—and checked for IDA and Wireshark processes as anti-analysis measures.
Uses the GuardBreaker AI anti-analysis technique: a malicious prompt injection embedded in a VBS-script comment intended to trigger LLM safety controls and prevent or degrade automated malware analysis. The VBS script downloads the MATCHBOIL C# loader for delivery of additional payloads.
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Every observed MITRE ATT&CK technique, grouped by tactic.
Families this actor is known to deploy, with IOCs and behavior.
CVEs this actor has used in known campaigns.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Domains, IPs, and hashes tied to this actor, refreshed continuously.