CVE-2018-1121

Since the kernel's proc_pid_readdir() returns PID entries in ascending numeric order, a process occupying a high PID can use inotify events to determine when the process list is being scanned, and fork/exec to obtain a lower PID, thus avoiding enumeration. An unprivileged attacker can hide a process from procps-ng's utilities by exploiting a race condition in reading /proc/PID entries.

The /proc filesystem is not a reliable mechanism to account for processes running on a system, as it is unable to offer snapshot semantics. Short-lived processes have always been able to escape detection by tools that monitor /proc. This CVE simply identifies a reliable way to do so using inotify.

Process accounting for security purposes, or with a requirement to record very short-running processes and those attempting to evade detection, should be performed with more robust methods such as auditd(8) (the Linux Audit Daemon) or systemtap.

Because an attacker can achieve similar results whether this vulnerability is present or not, Red Hat assesses its impact as Low.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.