QNAP NetBak Replicator Flaw Lets Attackers Execute Unauthorized Code

QNAP Systems has disclosed a critical vulnerability in its NetBak Replicator backup software that could enable local attackers to execute arbitrary code on affected Windows systems.

Tracked as CVE-2025-57714, the flaw originates from an unquoted search path element in NetBak Replicator version 4.5.x.

When Windows attempts to locate executables in directory paths containing spaces without proper quotation marks, an attacker can insert a malicious executable into a higher-priority path.

Upon execution of the legitimate program, the operating system may inadvertently run the attacker’s code instead, leading to unauthorized code execution with elevated privileges.

The vulnerability affects NetBak Replicator 4.5.x and requires only local user account access.

In environments where multiple users share access or where a malicious actor has gained initial access through phishing or another exploit, the flaw presents a real risk of privilege escalation and persistence.

Organizations relying on NetBak Replicator for critical backup operations should treat this vulnerability with the highest priority.

Exploitation and Risk

The exploitation prerequisites for CVE-2025-57714 are straightforward.

An attacker needs local access to a standard user account on the target system.

After placing a malicious executable named to match a legitimate NetBak Replicator component into a directory earlier in the Windows search path, any attempt by the system to launch the backup utility may instead run the attacker’s code.

This classic Windows security weakness, applications mismanaging file paths with spaces, has long been recognized but persists in NetBak Replicator’s implementation.

Once executed, the malicious code can run with the privileges of the NetBak Replicator service, potentially allowing an attacker to install additional backdoors or escalate privileges to an administrative level.

Security researchers led by Kazuma Matsumoto of GMO Cybersecurity by IERAE, Inc., discovered this flaw and reported it responsibly to QNAP.

Their findings highlight the importance of thorough path-handling checks during software development.

In shared computing environments such as terminal servers, virtual desktop infrastructures, or systems managed by multiple administrators, the risk amplifies.

An attacker could chain this flaw with lateral movement techniques to compromise entire networks.

QNAP has addressed CVE-2025-57714 in NetBak Replicator version 4.5.15.0807 and subsequent releases.

Organizations running any 4.5.x versions should upgrade immediately to the patched build to remove the unquoted search path vulnerability.

Beyond updating, system administrators are advised to enforce defense-in-depth measures.

Implement strict access controls to limit local administrator privileges, deploy host-based intrusion detection to monitor for unusual process launches in backup directories, and conduct regular security assessments focusing on path and permission audits.

Maintaining current software versions across all QNAP utilities ensures ongoing protection against emerging threats.

In addition to patching, organizations should integrate vulnerability scanning into their change-management processes to detect similar path-related issues.

By combining timely updates with robust monitoring and access policies, enterprises can mitigate the risk posed by unquoted search path vulnerabilities before adversaries exploit them.

Cyber Awareness Month Offer: Upskill With 100+ Premium Cybersecurity Courses From EHA's Diamond Membership: Join Today