cis-gcp-cos-1-4-1

name	cis-gcp-cos-1.4.1
description	Ensure core dumps are restricted
category	cis-gcp-cos
version	1.2.0
author	cyberstrike-official
tags	["cis","gcp","container-optimized-os","core-dumps","process-hardening"]
cis_id	1.4.1
cis_benchmark	CIS Google Container-Optimized OS Benchmark v1.2.0
tech_stack	["gcp","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

1.4.1 Ensure core dumps are restricted (Automated)

Description

A core dump is the memory of an executable program. It is generally used to determine why a program aborted. It can also be used to glean confidential information from a core file. The system provides the ability to set a soft limit for core dumps, but this can be overridden by the user.

Rationale

Setting a hard limit on core dumps prevents users from overriding the soft variable. If core dumps are required, consider setting limits for user groups (see limits.conf(5)). In addition, setting the fs.suid_dumpable variable to 0 will prevent setuid programs from dumping core.

Audit Procedure

Run the following commands and verify output matches:

# grep "hard core" /etc/security/limits.conf /etc/security/limits.d/*
* hard core 0

# sysctl fs.suid_dumpable
fs.suid_dumpable = 0

Run the following commands to check if systemd-coredump is installed:

# systemctl is-enabled systemd-coredump@.service
# systemctl is-enabled systemd-coredump.socket

If static is returned systemd-coredump is installed.

Expected Result

• * hard core 0 should be present in limits.conf or limits.d files.
• fs.suid_dumpable = 0 should be the output of sysctl.
• systemd-coredump should not be enabled unless properly configured.

Remediation

Add the following line to /etc/security/limits.conf or a /etc/security/limits.d/* file:

* hard core 0

Run the following command to set the active kernel parameter:

# sysctl -w fs.suid_dumpable=0

If systemd-coredump@ is installed, edit /etc/systemd/coredump.conf and add/modify the following lines:

Storage=none
ProcessSizeMax=0

Run the command:

systemctl daemon-reload

/etc is stateless on Container-Optimized OS. Therefore, /etc cannot be used to make these changes persistent across reboots. The steps mentioned above needs to be performed after every boot.