Cyber Threat Intelligence
CTI Academy Sponsor CTI Academy
SE
Ransomware Victim Technology

Seznam

Ransomware attack by Medusalocker · Disclosed September 23, 2026 · 🇨🇿 Czech Republic

seznam.cz

Date Disclosed
Sep 23, 2026
2026
Threat Group
Medusalocker
62 total victims
Country
🇨🇿 Czech Republic
Industry
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.

On 23 September 2026, cyber threat group Medusalocker added Seznam to its dark web leak site, a Czech Republic-based tech firm operating in that sector.

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 90 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 targeted by Medusalocker ransomware, one of the most active ransomware groups in our database with 62 confirmed victims globally. The attack was disclosed on September 23, 2026, when Seznam appeared on the group's dark web leak site.

Seznam is based in Czech Republic , operating in the Technology sector. Czech Republic ranks #33 globally for ransomware attacks, with 91 victims in our 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 employs a double extortion model: first exfiltrating sensitive data from the victim's systems, then deploying ransomware to encrypt files. Victims face two simultaneous threats — paying to restore access and paying to prevent publication of stolen data. The group's leak site publishes victim names and exfiltrated data as leverage.

Data source: This incident record is sourced from public ransomware group leak site disclosures aggregated via the ransomware.live API. Disclosure date reflects when the victim was published on the leak site, which may differ from the initial date of compromise. This platform does not publish or link to stolen data. Last data update: Sep 29, 2026 16:00 UTC.

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 62 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.