K00854051 : Linux kernel vulnerability CVE-2018-13405

Security Advisory Description

The inode_init_owner function in fs/inode.c in the Linux kernel through 4.17.4 allows local users to create files with an unintended group ownership, in a scenario where a directory is SGID to a certain group and is writable by a user who is not a member of that group. Here, the non-member can trigger creation of a plain file whose group ownership is that group. The intended behavior was that the non-member can trigger creation of a directory (but not a plain file) whose group ownership is that group. The non-member can escalate privileges by making the plain file executable and SGID. (CVE-2018-13405)

Impact

Local users are able to create files with an unintended group ownership, allowing attackers to escalate privileges and obtain sensitive information that may aid in further attacks.