Record Unsuccessful Modification Attempts to Files - openat O_TRUNC_WRITE

An XCCDF Rule

Description

The audit system should collect detailed unauthorized file accesses for all users and root. The openat syscall can be used to modify files if called for write operation of with O_TRUNC_WRITE flag. The following auidt rules will asure that unsuccessful attempts to modify a file via openat syscall are collected. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the rules below to 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, add the rules below to /etc/audit/audit.rules file.

-a always,exit -F arch=b32 -S openat -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
-a always,exit -F arch=b32 -S openat -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification

If the system is 64 bit then also add the following lines:

-a always,exit -F arch=b64 -S openat -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
-a always,exit -F arch=b64 -S openat -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification

warning alert: Warning

Note that these rules can be configured in a number of ways while still achieving the desired effect. Here the system calls have been placed independent of other system calls. Grouping system calls related to the same event is more efficient. See the following example:

-a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification

Rationale

Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise.

ID: xccdf_org.ssgproject.content_rule_audit_rules_unsuccessful_file_modification_openat_o_trunc_write
Severity: Medium
References: 1 11 12 13 14 15 16 19 2 3 4 5 6 7 8 9

APO10.01 APO10.03 APO10.04 APO10.05 APO11.04 APO12.06 APO13.01 BAI03.05 BAI08.02 DSS01.03 DSS01.04 DSS02.02 DSS02.04 DSS02.07 DSS03.01 DSS03.05 DSS05.02 DSS05.03 DSS05.04 DSS05.05 DSS05.07 MEA01.01 MEA01.02 MEA01.03 MEA01.04 MEA01.05 MEA02.01

3.1.7

CCI-000172 CCI-002884

164.308(a)(1)(ii)(D) 164.308(a)(3)(ii)(A) 164.308(a)(5)(ii)(C) 164.312(a)(2)(i) 164.312(b) 164.312(d) 164.312(e)

4.2.3.10 4.3.2.6.7 4.3.3.3.9 4.3.3.5.8 4.3.3.6.6 4.3.4.4.7 4.3.4.5.6 4.3.4.5.7 4.3.4.5.8 4.4.2.1 4.4.2.2 4.4.2.4

SR 1.13 SR 2.10 SR 2.11 SR 2.12 SR 2.6 SR 2.8 SR 2.9 SR 3.1 SR 3.5 SR 3.8 SR 4.1 SR 4.3 SR 5.1 SR 5.2 SR 5.3 SR 6.1 SR 6.2 SR 7.1 SR 7.6

A.11.2.6 A.12.4.1 A.12.4.2 A.12.4.3 A.12.4.4 A.12.7.1 A.13.1.1 A.13.2.1 A.14.1.3 A.14.2.7 A.15.2.1 A.15.2.2 A.16.1.4 A.16.1.5 A.16.1.7 A.6.2.1 A.6.2.2

AU-12(c) AU-2(d) CM-6(a)

DE.AE-3 DE.AE-5 DE.CM-1 DE.CM-3 DE.CM-7 ID.SC-4 PR.AC-3 PR.PT-1 PR.PT-4 RS.AN-1 RS.AN-4

FAU_GEN.1.1.c

Req-10.2.1 Req-10.2.4

SRG-OS-000064-GPOS-00033 SRG-OS-000392-GPOS-00172 SRG-OS-000458-GPOS-00203 SRG-OS-000461-GPOS-00205
Updated: about 1 year ago

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.7
  - NIST-800-53-AU-12(c)  - NIST-800-53-AU-2(d)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.2.1
  - PCI-DSS-Req-10.2.4
  - audit_rules_unsuccessful_file_modification_openat_o_trunc_write
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

- name: Add unsuccessful file operations audit rules
  blockinfile:
    path: /etc/audit/rules.d/30-ospp-v42-remediation.rules
    create: true
    block: |-
      ## This content is a section of an Audit config snapshot recommended for Red Hat Enterprise Linux 9 systems that target OSPP compliance.
      ## The following content has been retreived on 2019-03-11 from: https://github.com/linux-audit/audit-userspace/blob/master/rules/30-ospp-v42.rules

      ## The purpose of these rules is to meet the requirements for Operating
      ## System Protection Profile (OSPP)v4.2. These rules depends on having
      ## 10-base-config.rules, 11-loginuid.rules, and 43-module-load.rules installed.

      ## Unsuccessful file creation (open with O_CREAT)
      -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
      -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&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=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
      -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=b32 -S openat,open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
      -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F exit=-EPERM -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=b64 -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 creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
      -a always,exit -F arch=b64 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
      -a always,exit -F arch=b32 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
      -a always,exit -F arch=b64 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create

      ## Unsuccessful file modifications (open for write or truncate)
      -a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
      -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&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=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
      -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=b32 -S openat,open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
      -a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F exit=-EPERM -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=b64 -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 truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
      -a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
      -a always,exit -F arch=b32 -S truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
      -a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification

      ## Unsuccessful file access (any other opens) This has to go last.
      -a always,exit -F arch=b32 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access
      -a always,exit -F arch=b64 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access
      -a always,exit -F arch=b32 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-access
      -a always,exit -F arch=b64 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-access
  when:
  - '"audit" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-171-3.1.7
  - NIST-800-53-AU-12(c)
  - NIST-800-53-AU-2(d)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.2.1
  - PCI-DSS-Req-10.2.4
  - audit_rules_unsuccessful_file_modification_openat_o_trunc_write
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy

# Remediation is applicable only in certain platforms
if [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ] && rpm --quiet -q audit; 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.## The following content has been retreived on 2019-03-11 from: https://github.com/linux-audit/audit-userspace/blob/master/rules/30-ospp-v42.rules

## The purpose of these rules is to meet the requirements for Operating
## System Protection Profile (OSPP)v4.2. These rules depends on having
## 10-base-config.rules, 11-loginuid.rules, and 43-module-load.rules installed.

## Unsuccessful file creation (open with O_CREAT)
-a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&0100 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
-a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&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=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
-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=b32 -S openat,open_by_handle_at -F a2&0100 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
-a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&0100 -F exit=-EPERM -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=b64 -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 creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
-a always,exit -F arch=b64 -S creat -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
-a always,exit -F arch=b32 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create
-a always,exit -F arch=b64 -S creat -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-create

## Unsuccessful file modifications (open for write or truncate)
-a always,exit -F arch=b32 -S openat,open_by_handle_at -F a2&01003 -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
-a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&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=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
-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=b32 -S openat,open_by_handle_at -F a2&01003 -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
-a always,exit -F arch=b64 -S openat,open_by_handle_at -F a2&01003 -F exit=-EPERM -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=b64 -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 truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
-a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
-a always,exit -F arch=b32 -S truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification
-a always,exit -F arch=b64 -S truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-modification

## Unsuccessful file access (any other opens) This has to go last.
-a always,exit -F arch=b32 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access
-a always,exit -F arch=b64 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=unsuccesful-access
-a always,exit -F arch=b32 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-access
-a always,exit -F arch=b64 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=unsuccesful-access
EOF

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

Record Unsuccessful Modification Attempts to Files - openat O_TRUNC_WRITE

Description

Rationale

Remediation - Ansible

Remediation - Shell Script