Network administrators and software developers with applications using the Samba suite of utilities are urged to install the latest patches after the discovery of a serious vulnerability.
According to the U.S. CERT Co-ordination Center, the vulnerability (CVE-2021-44142) in the Samba vfs_fruit module allows out-of-bounds heap read and write via extended file attributes.
In other words, it allows a remote attacker to execute arbitrary code with root privileges.
All versions of Samba prior to 4.13.17 that use the affected module are vulnerable.
If an attacker has write access to a file’s extended attributes — even as a guest or unauthenticated user — the vulnerability can be exploited.
Samba issued security releases 4.13.17, 4.14.12 and 4.15 to correct the defect.
There is also a workaround involving changing the VFS module settings, however, Samba notes doing that causes all stored information to be inaccessible, “and will make it appear to macOS clients as if the information is lost.”
Samba is a standard Windows interoperability suite of programs for Linux and Unix. it provides file and print services for all clients using the SMB/CIFS protocol, including all versions of DOS and Windows, OS/2, Linux and many others. As a result it helps integrate Linux/Unix servers and desktops into Windows Active Directory environments. Samba says the suite can function both as a domain controller or as a regular domain member.
According to the CERT Co-ordination Center, Linux distributions from Red Hat, Ubuntu and SUSE Linux are affected.