VU#687587: AOMEI Backupper amwrtdrv.sys local privilege escalation vulnerability allows arbitrary writes to physical disks

An incorrect permissions assignment vulnerability in the amwrtdrv.sys kernel driver, included with AOMEI Backupper 8.4.0, allows an unprivileged local user to perform arbitrary writes to the physical disk. When Secure Boot is disabled, this can be leveraged to execute arbitrary UEFI-level code before the operating system loads. This allows an attacker to bypass OS-level security controls, including HVCI, EDR solutions, and Microsoft Defender. The attack may also enable capture of BitLocker Volume Master Key (VMK) material, depending on the system's BitLocker configuration.

AOMEI Backupper from AOMEI International Network Limited is designed to provide backup and disaster recovery services. It also helps individuals and businesses to create system images, disk clones, and file backups. AOMEI Backupper is available as a Windows application and can be integrated into enterprise backup workflows or directly used by end users.

CVE-2026-12780: An Incorrect Permission Assignment for Critical Resource (CWE-732) vulnerability in the amwrtdrv.sys kernel driver used by AOMEI Backupper 8.4.0 allows an unprivileged local attacker to achieve UEFI-level arbitrary code execution by directly writing to physical disk devices. The driver creates a world-accessible device object without a security descriptor, therefore allowing any user-mode process to open the device and issue unrestricted write requests. Hence, an attacker can modify disk sectors in the pre-partition gap (LBA 34–2047), inject a malicious UEFI payload, and alter the GPT to reference the payload as an EFI System Partition. The payload can then execute during the UEFI Boot Device Selection (BDS) phase, before operating system security mechanisms are loaded.