A newly discovered local privilege escalation vulnerability dubbed 'CIFSwitch' in the Linux kernel could allow attackers to forge CIFS authentication key descriptions, abuse the kernel's key request mechanism, and gain root privileges.
The issue impacts multiple Linux distributions that ship vulnerable combinations of the kernel CIFS and cifs-utils (versions 6.14 and higher, although some older variants are also affected).
CIFS (Common Internet File System) is a networking protocol that allows access to files, folders, and devices across a local network. Linux uses it to mount, read, and write data from remote systems.
If a CIFS network share uses Kerberos for authentication, the Linux kernel asks a helper program in user space to perform authentication, with the cifs-utils collection of user-space tools serving as the intermediary.
"The kernel requests a cifs.spnego-type key, and the normal keyutils/request-key config runs cifs.upcall as root to fetch or build the Kerberos/SPNEGO material," explains Asim Viladi Oglu Manizada, a SpaceX security engineer who discovered and named the CIFSwitch privilege escalation vulnerability in Linux.
