# Source: https://docs.datadoghq.com/security/default_rules/def-000-3wi.md

---
title: Ensure System Log Files Have Correct Permissions
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > OOTB Rules > Ensure System Log Files Have Correct
  Permissions
---

# Ensure System Log Files Have Correct Permissions
 
## Description{% #description %}

The file permissions for all log files written by `rsyslog` should be set to 640, or more restrictive. These log files are determined by the second part of each Rule line in `/etc/rsyslog.conf` and typically all appear in `/var/log`. For each log file *LOGFILE* referenced in `/etc/rsyslog.conf`, run the following command to inspect the file's permissions:

```
$ ls -l LOGFILE
        
```

If the permissions are not 640 or more restrictive, run the following command to correct this:

```
$ sudo chmod 640 LOGFILE
        
```

"

## Rationale{% #rationale %}

Log files can contain valuable information regarding system configuration. If the system log files are not protected unauthorized users could change the logged data, eliminating their forensic value.

## Remediation{% #remediation %}

### Shell script{% #shell-script %}

The following script can be run on the host to remediate the issue.

```bash
#!/bin/bash

# Remediation is applicable only in certain platforms
if [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; then

# List of log file paths to be inspected for correct permissions
# * Primarily inspect log file paths listed in /etc/rsyslog.conf
RSYSLOG_ETC_CONFIG="/etc/rsyslog.conf"
# * And also the log file paths listed after rsyslog's $IncludeConfig directive
#   (store the result into array for the case there's shell glob used as value of IncludeConfig)
readarray -t OLD_INC < <(grep -e "\$IncludeConfig[[:space:]]\+[^[:space:];]\+" /etc/rsyslog.conf | cut -d ' ' -f 2)
readarray -t RSYSLOG_INCLUDE_CONFIG < <(for INCPATH in "${OLD_INC[@]}"; do eval printf '%s\\n' "${INCPATH}"; done)
readarray -t NEW_INC < <(sed -n '/^\s*include(/,/)/Ip' /etc/rsyslog.conf | sed -n 's@.*file\s*=\s*"\([/[:alnum:][:punct:]]*\)".*@\1@Ip')
readarray -t RSYSLOG_INCLUDE < <(for INCPATH in "${NEW_INC[@]}"; do eval printf '%s\\n' "${INCPATH}"; done)

# Declare an array to hold the final list of different log file paths
declare -a LOG_FILE_PATHS

# Array to hold all rsyslog config entries
RSYSLOG_CONFIGS=()
RSYSLOG_CONFIGS=("${RSYSLOG_ETC_CONFIG}" "${RSYSLOG_INCLUDE_CONFIG[@]}" "${RSYSLOG_INCLUDE[@]}")

# Get full list of files to be checked
# RSYSLOG_CONFIGS may contain globs such as
# /etc/rsyslog.d/*.conf /etc/rsyslog.d/*.frule
# So, loop over the entries in RSYSLOG_CONFIGS and use find to get the list of included files.
RSYSLOG_CONFIG_FILES=()
for ENTRY in "${RSYSLOG_CONFIGS[@]}"
do
	# If directory, rsyslog will search for config files in recursively.
	# However, files in hidden sub-directories or hidden files will be ignored.
	if [ -d "${ENTRY}" ]
	then
		readarray -t FINDOUT < <(find "${ENTRY}" -not -path '*/.*' -type f)
		RSYSLOG_CONFIG_FILES+=("${FINDOUT[@]}")
	elif [ -f "${ENTRY}" ]
	then
		RSYSLOG_CONFIG_FILES+=("${ENTRY}")
	else
		echo "Invalid include object: ${ENTRY}"
	fi
done

# Browse each file selected above as containing paths of log files
# ('/etc/rsyslog.conf' and '/etc/rsyslog.d/*.conf' in the default configuration)
for LOG_FILE in "${RSYSLOG_CONFIG_FILES[@]}"
do
	# From each of these files extract just particular log file path(s), thus:
	# * Ignore lines starting with space (' '), comment ('#"), or variable syntax ('$') characters,
	# * Ignore empty lines,
	# * Strip quotes and closing brackets from paths.
	# * Ignore paths that match /dev|/etc.*\.conf, as those are paths, but likely not log files
	# * From the remaining valid rows select only fields constituting a log file path
	# Text file column is understood to represent a log file path if and only if all of the
	# following are met:
	# * it contains at least one slash '/' character,
	# * it is preceded by space
	# * it doesn't contain space (' '), colon (':'), and semicolon (';') characters
	# Search log file for path(s) only in case it exists!
	if [[ -f "${LOG_FILE}" ]]
	then
		NORMALIZED_CONFIG_FILE_LINES=$(sed -e "/^[#|$]/d" "${LOG_FILE}")
		LINES_WITH_PATHS=$(grep '[^/]*\s\+\S*/\S\+$' <<< "${NORMALIZED_CONFIG_FILE_LINES}")
		FILTERED_PATHS=$(awk '{if(NF>=2&&($NF~/^\//||$NF~/^-\//)){sub(/^-\//,"/",$NF);print $NF}}' <<< "${LINES_WITH_PATHS}")
		CLEANED_PATHS=$(sed -e "s/[\"')]//g; /\\/etc.*\.conf/d; /\\/dev\\//d" <<< "${FILTERED_PATHS}")
		MATCHED_ITEMS=$(sed -e "/^$/d" <<< "${CLEANED_PATHS}")
		# Since above sed command might return more than one item (delimited by newline), split
		# the particular matches entries into new array specific for this log file
		readarray -t ARRAY_FOR_LOG_FILE <<< "$MATCHED_ITEMS"
		# Concatenate the two arrays - previous content of $LOG_FILE_PATHS array with
		# items from newly created array for this log file
		LOG_FILE_PATHS+=("${ARRAY_FOR_LOG_FILE[@]}")
		# Delete the temporary array
		unset ARRAY_FOR_LOG_FILE
	fi
done

# Check for RainerScript action log format which might be also multiline so grep regex is a bit
# curly:
# extract possibly multiline action omfile expressions
# extract File="logfile" expression
# match only "logfile" expression
for LOG_FILE in "${RSYSLOG_CONFIG_FILES[@]}"
do
	ACTION_OMFILE_LINES=$(grep -iozP "action\s*\(\s*type\s*=\s*\"omfile\"[^\)]*\)" "${LOG_FILE}")
	OMFILE_LINES=$(echo "${ACTION_OMFILE_LINES}"| grep -iaoP "\bFile\s*=\s*\"([/[:alnum:][:punct:]]*)\"\s*\)")
	LOG_FILE_PATHS+=("$(echo "${OMFILE_LINES}"| grep -oE "\"([/[:alnum:][:punct:]]*)\""|tr -d "\"")")
done

# Ensure the correct attribute if file exists
FILE_CMD="chmod"
for LOG_FILE_PATH in "${LOG_FILE_PATHS[@]}"
do
	# Sanity check - if particular $LOG_FILE_PATH is empty string, skip it from further processing
	if [ -z "$LOG_FILE_PATH" ]
	then
		continue
	fi
	$FILE_CMD "0640" "$LOG_FILE_PATH"
done

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi
```

### Ansible playbook{% #ansible-playbook %}

The following playbook can be run with Ansible to remediate the issue.

```
- name: Ensure System Log Files Have Correct Permissions - Set rsyslog logfile configuration
    facts
  ansible.builtin.set_fact:
    rsyslog_etc_config: /etc/rsyslog.conf
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CCE-80191-0
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSS-Req-10.5.2
  - PCI-DSSv4-10.3.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - rsyslog_files_permissions

- name: Ensure System Log Files Have Correct Permissions - Get IncludeConfig directive
  ansible.builtin.shell: |
    set -o pipefail
    grep -e '$IncludeConfig' {{ rsyslog_etc_config }} | cut -d ' ' -f 2 || true
  register: rsyslog_old_inc
  changed_when: false
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CCE-80191-0
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSS-Req-10.5.2
  - PCI-DSSv4-10.3.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - rsyslog_files_permissions

- name: Ensure System Log Files Have Correct Permissions - Get include files directives
  ansible.builtin.shell: |
    set -o pipefail
    awk '/)/{f=0} /include\(/{f=1} f{ nf=gensub("^(include\\(|\\s*)file=\"(\\S+)\".*","\\2",1); if($0!=nf){ print nf }}' {{ rsyslog_etc_config }} || true
  register: rsyslog_new_inc
  changed_when: false
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CCE-80191-0
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSS-Req-10.5.2
  - PCI-DSSv4-10.3.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - rsyslog_files_permissions

- name: Ensure System Log Files Have Correct Permissions - Aggregate rsyslog includes
  ansible.builtin.set_fact:
    include_config_output: '{{ rsyslog_old_inc.stdout_lines + rsyslog_new_inc.stdout_lines
      }}'
  when:
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - rsyslog_old_inc is not skipped and rsyslog_new_inc is not skipped
  tags:
  - CCE-80191-0
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSS-Req-10.5.2
  - PCI-DSSv4-10.3.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - rsyslog_files_permissions

- name: Ensure System Log Files Have Correct Permissions - List all config files
  ansible.builtin.find:
    paths: '{{ item | dirname }}'
    patterns: '{{ item | basename }}'
    hidden: false
    follow: true
  loop: '{{ include_config_output | list + [rsyslog_etc_config] }}'
  when:
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - include_config_output is defined
  register: rsyslog_config_files
  failed_when: false
  changed_when: false
  tags:
  - CCE-80191-0
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSS-Req-10.5.2
  - PCI-DSSv4-10.3.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - rsyslog_files_permissions

- name: Ensure System Log Files Have Correct Permissions - Extract log files old format
  ansible.builtin.shell: |
    set -o pipefail
    grep -oP '^[^(\s|#|\$)]+[\s]+.*[\s]+-?(/+[^:;\s]+);*\.*$' {{ item.1.path }} | \
    awk '{print $NF}' | \
    sed -e 's/^-//' || true
  loop: '{{ rsyslog_config_files.results | default([]) | subelements(''files'') }}'
  register: log_files_old
  changed_when: false
  when:
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - rsyslog_config_files is not skipped
  tags:
  - CCE-80191-0
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSS-Req-10.5.2
  - PCI-DSSv4-10.3.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - rsyslog_files_permissions

- name: Ensure System Log Files Have Correct Permissions - Extract log files new format
  ansible.builtin.shell: |
    set -o pipefail
    grep -ozP "action\s*\(\s*type\s*=\s*\"omfile\"[^\)]*\)" {{ item.1.path }} | \
    grep -aoP "\bFile\s*=\s*\"([/[:alnum:][:punct:]]*)\"\s*\)" | \
    grep -oE "\"([/[:alnum:][:punct:]]*)\"" | \
    tr -d "\""|| true
  loop: '{{ rsyslog_config_files.results | default([]) | subelements(''files'') }}'
  register: log_files_new
  changed_when: false
  when:
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - rsyslog_config_files is not skipped
  tags:
  - CCE-80191-0
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSS-Req-10.5.2
  - PCI-DSSv4-10.3.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - rsyslog_files_permissions

- name: Ensure System Log Files Have Correct Permissions - Sum all log files found
  ansible.builtin.set_fact:
    log_files: '{{ log_files_new.results | map(attribute=''stdout_lines'') | list
      | flatten | unique + log_files_old.results | map(attribute=''stdout_lines'')
      | list | flatten | unique }}'
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CCE-80191-0
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSS-Req-10.5.2
  - PCI-DSSv4-10.3.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - rsyslog_files_permissions

- name: Ensure System Log Files Have Correct Permissions -Setup log files attribute
  ansible.builtin.file:
    path: '{{ item }}'
    mode: '0640'
    state: file
  loop: '{{ log_files | list | flatten | unique }}'
  failed_when: false
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CCE-80191-0
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.1
  - PCI-DSS-Req-10.5.2
  - PCI-DSSv4-10.3.1
  - configure_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - rsyslog_files_permissions
```