Ensure auditd Rules For Unauthorized Attempts To open Are Ordered Correctly
An XCCDF Rule
Description
The audit system should collect detailed unauthorized file
accesses for all users and root.
To correctly identify unsuccessful creation, unsuccessful modification and unsuccessful access
of files via open syscall the audit rules collecting these events need to be in certain order.
The more specific rules need to come before the less specific rules. The reason for that is that more
specific rules cover a subset of events covered in the less specific rules, thus, they need to come
before to not be overshadowed by less specific rules, which match a bigger set of events.
Make sure that rules for unsuccessful calls of open syscall are in the order shown below.
If the auditd daemon is configured to use the augenrules
program to read audit rules during daemon startup (the default), check the order of
rules below in a file with suffix .rules in the directory
/etc/audit/rules.d.
If the auditd daemon is configured to use the auditctl
utility to read audit rules during daemon startup, check the order of rules below in
/etc/audit/audit.rules file.
-a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b32 -S open -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access -a always,exit -F arch=b32 -S open -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-accessIf the system is 64 bit then also add the following lines:
-a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S open -F a1&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S open -F a1&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification -a always,exit -F arch=b64 -S open -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access -a always,exit -F arch=b64 -S open -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-access
Rationale
The more specific rules cover a subset of events covered by the less specific rules. By ordering them from more specific to less specific, it is assured that the less specific rule will not catch events better recorded by the more specific rule.
- ID
- xccdf_org.ssgproject.content_rule_audit_rules_unsuccessful_file_modification_open_rule_order
- Severity
- Medium
- References
- Updated
Remediation - Shell Script
# Remediation is applicable only in certain platforms
if [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ] && rpm --quiet -q audit && { ! ( grep -q aarch64 /proc/sys/kernel/osrelease ); }; then
mkdir -p "$(dirname '/etc/audit/rules.d/30-ospp-v42-remediation.rules')"
cat <<EOF > "/etc/audit/rules.d/30-ospp-v42-remediation.rules"
## This content is a section of an Audit config snapshot recommended for linux systems that target OSPP compliance.