Executive brief
A vulnerability in the FreeBSD and NetBSD operating systems allows users to bypass file protections. Specifically, it enables the modification of files that were intended to be permanent or append-only, such as system logs or security configurations. This could allow an attacker to hide their tracks or compromise the integrity of the entire system.
Technical details
A vulnerability exists in the mmap system call implementation within FreeBSD and NetBSD. The flaw allows a local user to map a file into memory with write permissions even if the file is marked with the 'append-only' or 'immutable' system flags. By modifying the memory-mapped region, the attacker can bypass filesystem-level protections intended to preserve the integrity of critical system files and logs. This is a local privilege escalation or integrity bypass vulnerability. Patches were historically addressed in NetBSD-SA1998-003 and corresponding FreeBSD security updates.
Affected products
- FreeBSD FreeBSD
- NetBSD NetBSD
Timeline
- 1998-02-20: disclosed
- 1998-02-20: advisory