DHS confirms breach of HSIN information sharing platform

The Department of Homeland Security is investigating a cyberattack on its Homeland Security Information Network, a sensitive platform used by government and private-sector partners to coordinate security and share intelligence. The intrusion, carried out by an unknown threat actor, occurred between late May and early June, according to officials familiar with the matter.

DHS confirmed the breach involved a specific, unclassified legacy information-sharing environment. The department stated it has isolated the affected systems, mitigated the vulnerability, and launched a forensic investigation. Officials said there is no indication that classified networks were impacted and that the system remains operational for its partners. The full extent of the breach is unclear, as DHS has not confirmed whether any documents were stolen from the system. The hackers reportedly targeted HSIN servers and a SharePoint system used for collaboration.

The HSIN platform is used by federal, state, local, territorial, tribal, international, and private-sector partners to access data, manage operations, coordinate safety for planned events, and respond to incidents. It supports real-time...