TA551
TA551 is a Russia-based cybercriminal threat actor also tracked as Shathak, Mario Kart, GOLD CABIN, and Monster Libra; additional aliases mentioned in the content include ATK236 and G0127. Court records cited in the content state that between 2017 and 2021 the group was co-managed by Ilya Angelov, who used the monikers "milan" and "okart," and that the FBI designated the group as Mario Kart. The same reporting states the group operated a botnet used in ransomware attacks against U.S. organizations. The content describes TA551 primarily as a malware distributor associated with spearphishing-driven initial access. Reported delivery tradecraft includes spearphishing attachments, including password-protected ZIP files, and lures that prompt users to enable macros. One intrusion described in the content attributes the distribution stage to TA551, with a separate hands-on-keyboard actor conducting later intrusion activity. In that November 2022 case, TA551 was assessed as the distributor for a thread-hijacked phishing campaign using HTML smuggling to deliver a password-protected ZIP containing an ISO and LNK-based execution chain that installed IcedID, after which a separate affiliate deployed Nokoyawa ransomware. The content explicitly associates TA551 with use of cmd.exe for command execution, HTTP for command-and-control communications, and encoded ASCII text for initial C2 communications. ATT&CK-style annotations in the content also associate TA551 with Windows Command Shell (T1059.003), Regsvr32 abuse (T1218.010), Command Obfuscation (T1027.010), Malicious File Execution (T1204.002), and spearphishing attachment activity including UDL-file-based lures. A separate 2026 report in the content describes an IcedID Stage-1 MSI dropper leading to Latrodectus Stage-2 activity and assesses the operation with medium-high confidence as TA577- or TA551-aligned based on delivery and infrastructure patterns. That report notes likely delivery via the KongTuke traffic distribution system and reiterates that IcedID infections linked to this ecosystem should be treated as ransomware-precursor events due to historical follow-on ransomware deployment.
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Tradecraft
30 distinct techniques observed across reporting, grouped by tactic. Hover any cell for the evidence excerpt; click through for MITRE's full description.
Associated malware families
12 malware families attributed to this actor across reporting.
7 additional families tracked in Mallory.
Associated vulnerabilities
2 CVEs this actor has used in observed campaigns. 2 of them exploited in the wild.
This detection identifies instances where Windows Explorer.exe spawns PowerShell or cmd.exe processes, particularly focusing on executions initiated by LNK files. This behavior is associated with the ZDI-CAN-25373 Windows shortcut zero-day vulnerability, where specially crafted LNK files are used to trigger malicious code execution through cmd.exe or powershell.exe. This technique has been actively exploited by multiple APT groups in targeted attacks through both HTTP and SMB delivery methods.
"A critical remote code execution (RCE) vulnerability, identified as CVE-2025-55182 and dubbed React2Shell, exists within the React Server Components (RSC) architecture, allowing unauthenticated attackers to execute arbitrary code..."
Observables
121 indicators attributed to this actor: domains, IPs, hashes, and other artifacts pulled from reporting. View more in app.
Recent activity
20 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Referenced as a threat actor associated with the command obfuscation technique using environment variable substrings in Windows command lines.
Listed as a threat actor associated with Windows Command Shell execution behavior relevant to this detection.
Listed in the detection annotations as a threat actor associated with EFI volume mounting / installation-related behavior.
Referenced as a threat actor associated with the Regsvr32 stealth technique (T1218.010).
The version that knows your environment.
Match sector + geo + tech-stack targeting against your real footprint.
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.