Impact of File-Open Hook Points on Backup Ratio in ROFBS on XFS
This study addresses the limitations of existing real-time backup mechanisms against ransomware, which often fail due to suboptimal placement of file-open hooks, allowing attackers to encrypt files during detection delays. Without altering the underlying ROFBS framework, the authors present the first systematic quantitative evaluation of five kernel hook points—may_open, inode_permission, do_dentry_open, security_file_open, and xfs_file_open—along the Linux file-open path under the XFS filesystem, assessing their impact on backup ratio and encryption scope. Empirical experiments on AlmaLinux employ three ransomware families: AvosLocker, Conti, and IceFire. Results demonstrate that xfs_file_open achieves the highest backup ratios (100.0% for Conti and 63.2% for IceFire) while consistently minimizing the total number of encrypted files; security_file_open performs best against AvosLocker (82.5%), underscoring the critical defensive value of filesystem-layer hooks.