Windows API Abuse Enables Unencrypted System Lockdown via GhostLock Attack

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Windows API Misuse Enables Ransomware-Like Disruption Without Encryption

Cybersecurity researchers have identified a previously unknown attack technique that enables ransomware-like disruption without encryption.

Dubbed “GhostLock,” This Method Exploits Legitimate Windows Operating System Behavior

Dubbed “GhostLock,” this method exploits legitimate Windows operating system behavior to render files inaccessible to users and processes, effectively crippling enterprise file-sharing environments.

According to Kim Dvash, leader of the Offensive Security team, “The technique involves leveraging the CreateFileW API to force files into an ‘exclusive lock’ state. By setting the dwShareMode parameter to 0, the attacker blocks all simultaneous access to the file, resulting in a STATUS_SHARING_VIOLATION error upon any attempt to read, modify, or delete the file.”

Exploitation Does Not Require Administrator Privileges

This exploitation does not require administrator privileges, allowing a low-privileged domain user with standard access rights to execute the attack over Server Message Block (SMB) protocol.

Operational Impact Mirrors Traditional Ransomware Attacks

The operational impact mirrors traditional ransomware attacks, causing critical enterprise systems, including ERP platforms, shared storage servers, and internal workflow applications, to become unusable.

Research Indicates That GhostLock Can Rapidly Lock Thousands of Files Within Minutes

Research indicates that GhostLock can rapidly lock thousands of files within minutes using multi-threaded scanning and parallel SMB requests. In large environments containing hundreds of thousands of files, this results in widespread operational paralysis very quickly.

Recovering From GhostLock Attacks Is Complex and Often Requires Administrative Intervention

Security experts caution that recovering from GhostLock attacks is complex and often requires administrative intervention at the storage level. Termination of malicious SMB sessions is not immediate and may necessitate collaboration among different operational teams.

Experts Recommend Implementing Proactive Measures to Detect GhostLock

Alerting when a single SMB session accumulates unusually high numbers of exclusive file handles
Monitoring large-scale file access patterns without corresponding write operations
Establishing joint incident response protocols between security and storage teams
Enabling NAS-level telemetry to track per-session handle usage in real-time
Improving visibility into SMB session behavior for early detection of such attacks

Organizations Must Adapt Their Security Monitoring Approach

Professor Triveni Singh emphasizes the significance of this non-encryption-based attack, stating that modern cyberattacks increasingly shift away from encryption-based ransomware towards disruption-based models. Organizations must adapt their security monitoring approach by focusing on behavior analytics and system-level telemetry rather than relying solely on malware signatures.