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Cyber Threat
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Ransomware victim Technology

Seznam

Listed by Medusalocker on · organisation based in Czech Republic

seznam.cz

Disclosed
Sep 23, 2026
Leak-site listing date
Threat group
Medusalocker
77 victims listed
Country
Czech Republic
#33 most targeted
Sector
Technology

ThreatAI analysis

Compiled from this incident record and the threat intelligence profile for Medusalocker. Figures and technique mappings are quoted from the source data, not inferred.

About the Medusalocker group

Medusa is a DDoS bot written in .NET 2.0. In its current incarnation its C&C protocol is based on HTTP, while its predecessor made use of IRC. Medusalocker has listed 103 victims since November 2021.

How Medusalocker is documented to operate

Parent PID Spoofing T1134.004 Stealth Privilege Escalation

Adversaries may spoof the parent process identifier (PPID) of a new process to evade process-monitoring defenses or to elevate privileges. New processes are typically spawned directly from their parent, or calling, process unless explicitly specified. One way of explicitly assigning the PPID of a new process is via the <codeCreateProcess</code API call, which supports a parameter that defines the PPID to use. This functionality is used by Windows features such as User Account Control (UAC) to correctly set the PPID after a requested elevated process is spawned by SYSTEM (typically via <codesvchost.exe</code or <codeconsent.exe</code) rather than the current user context.

MITRE ATT&CK reference

MITRE ATT&CK techniques attributed to Medusalocker across its recorded activity, not a finding about how Seznam was reached.

Incident analysis

Seznam was listed by Medusalocker ransomware, a group with 77 victims recorded in this database. The listing appeared on the group's leak site on September 23, 2026.

Seznam is based in Czech Republic and operates in the Technology sector. Czech Republic ranks #33 worldwide for ransomware disclosures, with 96 victims in this database.

Sector context. Technology companies hold intellectual property, customer data, and source code — all highly valuable assets. A successful ransomware attack can also put downstream customers at risk through supply chain exposure.

Medusalocker typically follows a double extortion model: data is exfiltrated from the victim's systems before files are encrypted, so the victim faces two demands at once — pay to restore access, and pay to keep stolen data unpublished. The leak site, where this listing appeared, is the lever for the second demand.

Source. Public leak-site disclosures aggregated via the ransomware.live API. The disclosure date is when the listing was published, which can differ from the date of compromise. This site does not publish or link to stolen data. Last updated .

Frequently asked questions

Was Seznam attacked by ransomware?

Yes. Seznam was listed as a victim of the Medusalocker ransomware group on September 23, 2026. The organisation is based in Czech Republic and operates in the Technology sector. The disclosure appeared on the group's dark web leak site.

Which ransomware group attacked Seznam?

Seznam was attacked by Medusalocker ransomware. Medusalocker is one of the most active ransomware groups, having claimed 77 victims globally. The group typically employs a double-extortion model: encrypting the victim's files and threatening to publish stolen data.

When did the Seznam ransomware attack occur?

The ransomware attack on Seznam was disclosed on September 23, 2026. This date reflects when the victim was published on the threat group's leak site, which may differ from the actual date of initial compromise.

What data was stolen in the Seznam ransomware attack?

The specific data stolen from Seznam has not been independently verified by this platform. Ransomware groups typically exfiltrate data before encrypting systems and use the threat of publication to pressure victims. As a Technology organisation, Seznam likely held source code, intellectual property, and customer data.

How can organisations protect against Medusalocker attacks?

To defend against Medusalocker and similar threat actors, organisations should: maintain regular offline backups tested for restoration; implement network segmentation to limit lateral movement; deploy multi-factor authentication on all remote access; use endpoint detection and response (EDR) tools; conduct regular phishing and security awareness training; and monitor threat intelligence feeds for indicators of compromise (IOCs) associated with active groups.