CVE-2025-5474 is a local privilege escalation vulnerability affecting version 11.3.87.0 of 2BrightSparks SyncBackFree, a popular backup and synchronization software. The vulnerability arises from improper link resolution before file access, classified under CWE-59 ('Improper Link Resolution Before File Access'). Specifically, the flaw exists in the Mirror functionality of SyncBackFree. An attacker with the ability to execute low-privileged code on the target system can create a junction (a type of symbolic link in Windows) that the software improperly follows. This misuse allows the attacker to manipulate the service into deleting arbitrary files. By exploiting this behavior, the attacker can escalate privileges from a low-privileged user to SYSTEM level, enabling execution of arbitrary code with the highest system privileges. Exploitation requires that the attacker already have some code execution capability at a low privilege level and that an administrator performs some user interaction, such as approving a prompt or running a process. The CVSS v3.0 base score is 7.3 (High), reflecting the significant confidentiality, integrity, and availability impacts possible, combined with the requirement for local access and user interaction. No public exploits are currently known in the wild, and no patches have been linked yet. This vulnerability was identified and assigned by the Zero Day Initiative (ZDI) as ZDI-CAN-26962.

For European organizations, this vulnerability poses a serious risk especially in environments where SyncBackFree is used for backup or file synchronization tasks on Windows systems. Successful exploitation allows attackers to gain SYSTEM-level privileges, potentially leading to full system compromise. This can result in unauthorized access to sensitive data, disruption of backup operations, deletion or tampering of critical files, and deployment of persistent malware. Given that backups are often trusted and have elevated privileges, compromising the backup software can undermine the integrity and availability of organizational data. The requirement for local code execution and administrator interaction somewhat limits remote exploitation but insider threats, phishing leading to initial low-privilege code execution, or compromised endpoints could serve as vectors. The high impact on confidentiality, integrity, and availability makes this a critical concern for sectors with sensitive data such as finance, healthcare, and government within Europe.

1. Immediate mitigation should include restricting local user permissions to prevent unauthorized code execution and limiting administrative user interactions with unknown or untrusted processes. 2. Organizations should monitor and audit the use of SyncBackFree, especially the Mirror functionality, to detect suspicious junction creation or file deletion activities. 3. Employ application whitelisting and endpoint protection solutions that can detect and block attempts to create or exploit junction points maliciously. 4. Until a patch is released, consider temporarily disabling or restricting the use of SyncBackFree on critical systems or replacing it with alternative backup solutions with no known vulnerabilities. 5. Educate administrators about the risk of approving unexpected prompts or running unverified processes related to SyncBackFree. 6. Implement strict network segmentation and endpoint security controls to reduce the risk of initial low-privilege code execution by attackers. 7. Once available, promptly apply vendor patches or updates addressing this vulnerability.