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Configure auditing of unsuccessful permission changes (AArch64)

An XCCDF Rule

Description

Ensure that unsuccessful attempts to change file or directory permissions are audited. The following rules configure audit as described above: 

## Unsuccessful permission change
-a always,exit -F arch=b32 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change
-a always,exit -F arch=b64 -S fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change
-a always,exit -F arch=b32 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change
-a always,exit -F arch=b64 -S fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change
Load new Audit rules into kernel by running: 
augenrules --load
Note: This rule uses a special set of Audit rules to comply with OSPP 4.2.1. You may reuse this rule in different profiles. If you decide to do so, it is recommended that you inspect contents of the file closely and make sure that they are alligned with your needs.

Rationale

Unsuccessful attempts to change permissions of files or directories might be signs of malicious activity. Having such events audited helps in monitoring and investigation of such activities.

ID
xccdf_org.ssgproject.content_rule_audit_perm_change_failed_aarch64
Severity
Medium
References
Updated



Remediation - Ansible

- name: Put contents into /etc/audit/rules.d/30-ospp-v42-5-perm-change-failed.rules
    according to policy
  copy:
    dest: /etc/audit/rules.d/30-ospp-v42-5-perm-change-failed.rules
    content: |
      ## Unsuccessful permission change

Remediation - Shell Script

# Remediation is applicable only in certain platforms
if [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ] && { grep -q aarch64 /proc/sys/kernel/osrelease; }; then

cat << 'EOF' > /etc/audit/rules.d/30-ospp-v42-5-perm-change-failed.rules
## Unsuccessful permission change
-a always,exit -F arch=b32 -S chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccessful-perm-change