CVE-2025-53395 is a high-severity local privilege escalation vulnerability affecting Paramount Macrium Reflect versions up to and including 2025-06-26. The vulnerability arises from an untrusted DLL search path behavior in the ReflectMonitor.exe process. Specifically, when a user with administrative privileges mounts a backup by opening a crafted .mrimgx backup file, the application loads a malicious VSSSvr.dll located in the same directory as the backup file. This DLL hijacking allows local attackers to execute arbitrary code with administrator privileges. The attack requires the attacker to place a specially crafted .mrimgx file and a malicious VSSSvr.dll in a directory accessible to the target user. Upon the administrator mounting the backup, ReflectMonitor.exe loads the attacker's DLL after the mount completes, thereby executing the attacker's code with elevated privileges. The vulnerability exploits the Windows DLL search order, where the application loads DLLs from the current working directory before system directories, enabling DLL hijacking. The CVSS v3.1 base score is 7.7, reflecting high severity due to the requirement of local access, administrative privileges, and user interaction (mounting the backup). The impact includes full compromise of system confidentiality, integrity, and availability due to arbitrary code execution at the highest privilege level. No known exploits in the wild have been reported yet, and no patches or updates have been linked in the provided information. This vulnerability is particularly dangerous in environments where Macrium Reflect is used for backup and recovery by administrators, as it can be leveraged to gain persistent, elevated access on critical systems.

For European organizations, the impact of CVE-2025-53395 can be significant, especially in sectors relying heavily on Macrium Reflect for backup and disaster recovery, such as finance, healthcare, government, and critical infrastructure. Successful exploitation results in full administrative control over affected systems, enabling attackers to deploy ransomware, steal sensitive data, disrupt operations, or establish persistent footholds. Given that backups are often trusted and used for system restoration, this vulnerability undermines the integrity of backup processes, potentially allowing attackers to compromise recovery mechanisms. The requirement for local access and administrative privileges limits remote exploitation but raises concerns about insider threats or attackers who have already gained limited access. In European organizations with strict data protection regulations like GDPR, such a compromise could lead to data breaches with legal and financial consequences. Additionally, the vulnerability could be leveraged in targeted attacks against high-value assets, increasing the risk to national security and critical services.

To mitigate CVE-2025-53395 effectively, European organizations should: 1) Immediately restrict local administrative access to trusted personnel only and monitor for unauthorized local access attempts. 2) Educate administrators to avoid mounting backup files from untrusted or unknown sources, especially .mrimgx files from external or user-writable directories. 3) Implement application whitelisting and restrict execution of DLLs from non-standard directories to prevent DLL hijacking. 4) Use file system permissions to prevent unprivileged users from placing files in directories where administrators mount backups. 5) Monitor and audit the use of Macrium Reflect and ReflectMonitor.exe processes for unusual DLL loading or execution behaviors. 6) Employ endpoint detection and response (EDR) solutions to detect anomalous DLL loads and privilege escalation attempts. 7) Stay alert for vendor patches or updates addressing this vulnerability and apply them promptly once available. 8) Consider isolating backup operations to dedicated, secured systems or virtual environments to limit exposure. 9) Conduct regular security awareness training emphasizing the risks of opening files from untrusted sources, even in backup contexts.