PortStarter
PortStarter is a Go-based backdoor used by the ransomware affiliate cluster TAC5279, which Sophos says overlaps with Microsoft’s Vanilla Tempest/DEV-0832 tracking, and IBM also notes possible associations between Hive0163 and developers behind PortStarter. It was observed in enterprise intrusions spanning November 2022 to June 2023, including cases involving Vice Society and later Rhysida ransomware, targeting organizations in government/logistics, logistics, education, and manufacturing. In the reported intrusions, initial access commonly involved valid VPN credentials on accounts without MFA, followed by discovery, lateral movement, credential theft, data exfiltration, and ransomware deployment. PortStarter was used for command-and-control and persistence; Sophos describes it as modifying firewall settings, opening ports, and connecting to configured C2 servers. Persistence was established via scheduled tasks such as 'System' and 'SystemCheck' that executed DLLs with rundll32. Observed PortStarter file paths included C:\Windows\System32\config\main.dll, c:\users\public\main.dll, and C:\ProgramData\schk.dll. Reported PortStarter C2 IPs in these cases were 156.96.62[.]58, 146.70.104[.]249, 51.77.102[.]106, 108.62.141[.]161, and 157.154.194[.]6. Sophos noted PortStarter was common in earlier Vice Society-linked cases and was not observed after TAC5279 transitioned to Rhysida, where SystemBC became the primary C2 method.
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Groups observed using it
3 distinct threat actors attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.
"...the threat actors deployed the PortStarter backdoor to establish C2 communications."
"...the threat actors deployed the PortStarter backdoor to establish C2 communications."
X-Force links the group to malware developers/operators such as Broomstick, Supper, PortStarter, SystemBC, and Rhysida ransomware...
Techniques & procedures
1 distinct technique documented for this family, organized by ATT&CK tactic.
Execution
1 techniquePersistence
1 techniquePrivilege Escalation
1 techniqueIOCs tracked for this family
5 indicators attributed across vendor reports, sandbox runs, and researcher write-ups. Full values are available in Mallory.
IPs, domains, and DNS infrastructure linked to this family.
Recent activity
3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Tool/malware family referenced as potentially associated (via Hive0163) but not described in this content.
Tool referenced as part of Vanilla Tempest’s tooling; specific functionality not described in the provided content.
Go-based backdoor used for C2 and persistence; can modify Windows firewall settings, open ports, and connect to pre-configured C2 servers. Observed persisted via scheduled tasks executing a DLL via rundll32.
The version that knows your environment.
Match every observed IP, domain, and hash against your live telemetry.
Named campaigns wielding this family, with evidence pinned to each claim.
CVEs this family uses for access and lateral movement.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Every documented technique, ranked by evidence weight.
Reddit, Mastodon, and CTI community discussion around this family.