Huntress: How a Brute Force Attack Unmasked a Ransomware Infrastructure Network

Huntress Uncovers Ransomware-as-a-Service Ecosystem Behind "Routine" RDP Brute-Force Attack

Security researchers at Huntress recently traced a seemingly ordinary Remote Desktop Protocol (RDP) brute-force attack to a sophisticated ransomware-as-a-service (RaaS) operation, exposing a network of initial access brokers and malicious infrastructure.

The incident began when Huntress’s SOC detected unusual domain enumeration activity on a network with an exposed RDP server a common but risky configuration. While brute-force attacks are frequent, this case stood out due to atypical behavior: the compromised account was accessed from multiple IP addresses, suggesting a single threat actor leveraging distributed infrastructure.

After gaining access, the attacker deviated from standard post-exploitation tactics. Instead of extracting credentials from Windows LSASS or the registry common methods in ransomware attacks they manually searched file shares and text files for passwords, an unusual approach that hinted at a more targeted operation.

Further investigation revealed the IP addresses involved were linked to known ransomware groups, including Hive and BlackSuite, as well as a suspicious VPN service (1vpns[.]com) marketed as "no-logs." The infrastructure included a web of geo-distributed servers under the domain specialsseason[.]com, with subdomains tied to multiple countries (e.g., NL-US.specialsseason[.]com, NL-RU.specialsseason[.]com). The naming convention and references to "big game hunting" a term for high-value ransomware targeting strongly indicated ties to RaaS operations.

The findings underscore how initial access brokers operate at scale, using legitimate-seeming services to obscure their activities. Huntress’s analysis also highlighted the value of digging beyond routine alerts, as even mundane incidents can reveal broader criminal ecosystems.

Key Indicators of Compromise (IOCs):

• IPs: 64.190.113[.]159, 147.135.36[.]162
• Domains: specialsseason[.]com, 1vpns[.]com
• Certificate Fingerprints (SHA-256): 6bc8b8f260f9f9bfea69863ef8d3c525568676ddadc09c14655191cad1acdb5b, b884cce828f06fb936fd5809d5945d861401c606c4ebe894464c99e6473e9570

  Source: https://www.bleepingcomputer.com/news/security/how-a-brute-force-attack-unmasked-a-ransomware-infrastructure-network/

  Huntress cybersecurity rating report: https://www.rankiteo.com/company/huntress-labs

"id": "HUN1772642134",
"linkid": "huntress-labs",
"type": "Cyber Attack",
"date": "3/2026",
"severity": "25",
"impact": "1",
"explanation": "Attack without any consequences"

{'attack_vector': 'RDP Brute-Force',
 'description': 'Security researchers at Huntress recently traced a seemingly '
                'ordinary Remote Desktop Protocol (RDP) brute-force attack to '
                'a sophisticated ransomware-as-a-service (RaaS) operation, '
                'exposing a network of initial access brokers and malicious '
                'infrastructure. The incident began when Huntress’s SOC '
                'detected unusual domain enumeration activity on a network '
                'with an exposed RDP server. The attacker deviated from '
                'standard post-exploitation tactics, manually searching file '
                'shares and text files for passwords, and was linked to known '
                'ransomware groups including Hive and BlackSuite.',
 'initial_access_broker': {'entry_point': 'Exposed RDP server',
                           'high_value_targets': 'Big game hunting (high-value '
                                                 'ransomware targets)'},
 'investigation_status': 'Completed',
 'lessons_learned': 'Even mundane incidents can reveal broader criminal '
                    'ecosystems. Initial access brokers operate at scale using '
                    'legitimate-seeming services to obscure their activities.',
 'motivation': 'Financial gain (Ransomware-as-a-Service)',
 'post_incident_analysis': {'root_causes': 'Exposed RDP server, distributed '
                                           'infrastructure for brute-force '
                                           'attacks, manual password '
                                           'harvesting from file shares/text '
                                           'files'},
 'ransomware': {'ransomware_strain': ['Hive', 'BlackSuite']},
 'recommendations': 'Investigate beyond routine alerts, monitor for atypical '
                    'post-exploitation behavior, and secure exposed RDP '
                    'servers.',
 'references': [{'source': 'Huntress'}],
 'threat_actor': ['Hive', 'BlackSuite', 'Initial Access Brokers'],
 'title': 'Huntress Uncovers Ransomware-as-a-Service Ecosystem Behind '
          "'Routine' RDP Brute-Force Attack",
 'type': 'Ransomware',
 'vulnerability_exploited': 'Exposed RDP server'}