Log USBGuard daemon audit events using Linux Audit

An XCCDF Rule

Description

To configure USBGuard daemon to log via Linux Audit (as opposed directly to a file), AuditBackend option in /etc/usbguard/usbguard-daemon.conf needs to be set to LinuxAudit.

Rationale

Using the Linux Audit logging allows for centralized trace of events.

ID: xccdf_org.ssgproject.content_rule_configure_usbguard_auditbackend
Severity: Low
References: CCI-000169 CCI-000172

AU-2 CM-8(3) IA-3

FMT_SMF_EXT.1

SRG-OS-000062-GPOS-00031 SRG-OS-000471-GPOS-00215

SRG-APP-000141-CTR-000315
Updated: about 1 year ago

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  annotations:
    complianceascode.io/depends-on: xccdf_org.ssgproject.content_rule_package_usbguard_installed    complianceascode.io/ocp-version: '>=4.7.0'
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,{{ %0A%23%0A%23%20Rule%20set%20file%20path.%0A%23%0A%23%20The%20USBGuard%20daemon%20will%20use%20this%20file%20to%20load%20the%20policy%0A%23%20rule%20set%20from%20it%20and%20to%20write%20new%20rules%20received%20via%20the%0A%23%20IPC%20interface.%0A%23%0A%23%20RuleFile%3D/path/to/rules.conf%0A%23%0ARuleFile%3D/etc/usbguard/rules.conf%0A%0A%23%0A%23%20Rule%20set%20folder%20path.%0A%23%0A%23%20The%20USBGuard%20daemon%20will%20use%20this%20folder%20to%20load%20the%20policy%0A%23%20rule%20set%20from%20it%20and%20to%20write%20new%20rules%20received%20via%20the%0A%23%20IPC%20interface.%20Usually%2C%20we%20set%20the%20option%20to%0A%23%20/etc/usbguard/rules.d/.%20The%20USBGuard%20daemon%20is%20supposed%20to%0A%23%20behave%20like%20any%20other%20standard%20Linux%20daemon%20therefore%20it%0A%23%20loads%20rule%20files%20in%20alpha-numeric%20order.%20File%20names%20inside%0A%23%20RuleFolder%20directory%20should%20start%20with%20a%20two-digit%20number%0A%23%20prefix%20indicating%20the%20position%2C%20in%20which%20the%20rules%20are%0A%23%20scanned%20by%20the%20daemon.%0A%23%0A%23%20RuleFolder%3D/path/to/rulesfolder/%0A%23%0ARuleFolder%3D/etc/usbguard/rules.d/%0A%0A%23%0A%23%20Implicit%20policy%20target.%0A%23%0A%23%20How%20to%20treat%20devices%20that%20don%27t%20match%20any%20rule%20in%20the%0A%23%20policy.%20One%20of%3A%0A%23%0A%23%20%2A%20allow%20%20-%20authorize%20the%20device%0A%23%20%2A%20block%20%20-%20block%20the%20device%0A%23%20%2A%20reject%20-%20remove%20the%20device%0A%23%0AImplicitPolicyTarget%3Dblock%0A%0A%23%0A%23%20Present%20device%20policy.%0A%23%0A%23%20How%20to%20treat%20devices%20that%20are%20already%20connected%20when%20the%0A%23%20daemon%20starts.%20One%20of%3A%0A%23%0A%23%20%2A%20allow%20%20%20%20%20%20%20%20-%20authorize%20every%20present%20device%0A%23%20%2A%20block%20%20%20%20%20%20%20%20-%20deauthorize%20every%20present%20device%0A%23%20%2A%20reject%20%20%20%20%20%20%20-%20remove%20every%20present%20device%0A%23%20%2A%20keep%20%20%20%20%20%20%20%20%20-%20just%20sync%20the%20internal%20state%20and%20leave%20it%0A%23%20%2A%20apply-policy%20-%20evaluate%20the%20ruleset%20for%20every%20present%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20device%0A%23%0APresentDevicePolicy%3Dapply-policy%0A%0A%23%0A%23%20Present%20controller%20policy.%0A%23%0A%23%20How%20to%20treat%20USB%20controllers%20that%20are%20already%20connected%0A%23%20when%20the%20daemon%20starts.%20One%20of%3A%0A%23%0A%23%20%2A%20allow%20%20%20%20%20%20%20%20-%20authorize%20every%20present%20device%0A%23%20%2A%20block%20%20%20%20%20%20%20%20-%20deauthorize%20every%20present%20device%0A%23%20%2A%20reject%20%20%20%20%20%20%20-%20remove%20every%20present%20device%0A%23%20%2A%20keep%20%20%20%20%20%20%20%20%20-%20just%20sync%20the%20internal%20state%20and%20leave%20it%0A%23%20%2A%20apply-policy%20-%20evaluate%20the%20ruleset%20for%20every%20present%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20device%0A%23%0APresentControllerPolicy%3Dkeep%0A%0A%23%0A%23%20Inserted%20device%20policy.%0A%23%0A%23%20How%20to%20treat%20USB%20devices%20that%20are%20already%20connected%0A%23%20%2Aafter%2A%20the%20daemon%20starts.%20One%20of%3A%0A%23%0A%23%20%2A%20block%20%20%20%20%20%20%20%20-%20deauthorize%20every%20present%20device%0A%23%20%2A%20reject%20%20%20%20%20%20%20-%20remove%20every%20present%20device%0A%23%20%2A%20apply-policy%20-%20evaluate%20the%20ruleset%20for%20every%20present%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20device%0A%23%0AInsertedDevicePolicy%3Dapply-policy%0A%0A%23%0A%23%20Control%20which%20devices%20are%20authorized%20by%20default.%0A%23%0A%23%20The%20USBGuard%20daemon%20modifies%20some%20the%20default%20authorization%20state%20attributes%0A%23%20of%20controller%20devices.%20This%20setting%2C%20enables%20you%20to%20define%20what%20value%20the%0A%23%20default%20authorization%20is%20set%20to.%0A%23%0A%23%20%2A%20keep%20%20%20%20%20%20%20%20%20-%20do%20not%20change%20the%20authorization%20state%0A%23%20%2A%20none%20%20%20%20%20%20%20%20%20-%20every%20new%20device%20starts%20out%20deauthorized%0A%23%20%2A%20all%20%20%20%20%20%20%20%20%20%20-%20every%20new%20device%20starts%20out%20authorized%0A%23%20%2A%20internal%20%20%20%20%20-%20internal%20devices%20start%20out%20authorized%2C%20external%20devices%20start%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20out%20deauthorized%20%28this%20requires%20the%20ACPI%20tables%20to%20properly%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20label%20internal%20devices%2C%20and%20kernel%20support%29%0A%23%0A%23AuthorizedDefault%3Dnone%0A%0A%23%0A%23%20Restore%20controller%20device%20state.%0A%23%0A%23%20The%20USBGuard%20daemon%20modifies%20some%20attributes%20of%20controller%0A%23%20devices%20like%20the%20default%20authorization%20state%20of%20new%20child%20device%0A%23%20instances.%20Using%20this%20setting%2C%20you%20can%20control%20whether%20the%0A%23%20daemon%20will%20try%20to%20restore%20the%20attribute%20values%20to%20the%20state%0A%23%20before%20modification%20on%20shutdown.%0A%23%0A%23%20SECURITY%20CONSIDERATIONS%3A%20If%20set%20to%20true%2C%20the%20USB%20authorization%0A%23%20policy%20could%20be%20bypassed%20by%20performing%20some%20sort%20of%20attack%20on%20the%0A%23%20daemon%20%28via%20a%20local%20exploit%20or%20via%20a%20USB%20device%29%20to%20make%20it%20shutdown%0A%23%20and%20restore%20to%20the%20operating-system%20default%20state%20%28known%20to%20be%20permissive%29.%0A%23%0ARestoreControllerDeviceState%3Dfalse%0A%0A%23%0A%23%20Device%20manager%20backend%0A%23%0A%23%20Which%20device%20manager%20backend%20implementation%20to%20use.%20One%20of%3A%0A%23%0A%23%20%2A%20uevent%20%20%20-%20Netlink%20based%20implementation%20which%20uses%20sysfs%20to%20scan%20for%20present%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20devices%20and%20an%20uevent%20netlink%20socket%20for%20receiving%20USB%20device%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20related%20events.%0A%23%20%2A%20umockdev%20-%20umockdev%20based%20device%20manager%20capable%20of%20simulating%20devices%20based%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20on%20umockdev-record%20files.%20Useful%20for%20testing.%0A%23%0ADeviceManagerBackend%3Duevent%0A%0A%23%21%21%21%20WARNING%3A%20It%27s%20good%20practice%20to%20set%20at%20least%20one%20of%20the%20%21%21%21%0A%23%21%21%21%20%20%20%20%20%20%20%20%20%20two%20options%20bellow.%20If%20none%20of%20them%20are%20set%2C%20%20%21%21%21%0A%23%21%21%21%20%20%20%20%20%20%20%20%20%20the%20daemon%20will%20accept%20IPC%20connections%20from%20%20%20%21%21%21%0A%23%21%21%21%20%20%20%20%20%20%20%20%20%20anyone%2C%20thus%20allowing%20anyone%20to%20modify%20the%20%20%20%20%21%21%21%0A%23%21%21%21%20%20%20%20%20%20%20%20%20%20rule%20set%20and%20%28de%29authorize%20USB%20devices.%20%20%20%20%20%20%20%21%21%21%0A%0A%23%0A%23%20Users%20allowed%20to%20use%20the%20IPC%20interface.%0A%23%0A%23%20A%20space%20delimited%20list%20of%20usernames%20that%20the%20daemon%20will%0A%23%20accept%20IPC%20connections%20from.%0A%23%0A%23%20IPCAllowedUsers%3Dusername1%20username2%20...%0A%23%0AIPCAllowedUsers%3Droot%0A%0A%23%0A%23%20Groups%20allowed%20to%20use%20the%20IPC%20interface.%0A%23%0A%23%20A%20space%20delimited%20list%20of%20groupnames%20that%20the%20daemon%20will%0A%23%20accept%20IPC%20connections%20from.%0A%23%0A%23%20IPCAllowedGroups%3Dgroupname1%20groupname2%20...%0A%23%0AIPCAllowedGroups%3Dwheel%0A%0A%23%0A%23%20IPC%20access%20control%20definition%20files%20path.%0A%23%0A%23%20The%20files%20at%20this%20location%20will%20be%20interpreted%20by%20the%20daemon%0A%23%20as%20access%20control%20definition%20files.%20The%20%28base%29name%20of%20a%20file%0A%23%20should%20be%20in%20the%20form%3A%0A%23%0A%23%20%20%20%5Buser%5D%5B%3A%3Cgroup%3E%5D%0A%23%0A%23%20and%20should%20contain%20lines%20in%20the%20form%3A%0A%23%0A%23%20%20%20%3Csection%3E%3D%5Bprivilege%5D%20...%0A%23%0A%23%20This%20way%20each%20file%20defines%20who%20is%20able%20to%20connect%20to%20the%20IPC%0A%23%20bus%20and%20what%20privileges%20he%20has.%0A%23%0AIPCAccessControlFiles%3D/etc/usbguard/IPCAccessControl.d/%0A%0A%23%0A%23%20Generate%20device%20specific%20rules%20including%20the%20%22via-port%22%0A%23%20attribute.%0A%23%0A%23%20This%20option%20modifies%20the%20behavior%20of%20the%20allowDevice%0A%23%20action.%20When%20instructed%20to%20generate%20a%20permanent%20rule%2C%0A%23%20the%20action%20can%20generate%20a%20port%20specific%20rule.%20Because%0A%23%20some%20systems%20have%20unstable%20port%20numbering%2C%20the%20generated%0A%23%20rule%20might%20not%20match%20the%20device%20after%20rebooting%20the%20system.%0A%23%0A%23%20If%20set%20to%20false%2C%20the%20generated%20rule%20will%20still%20contain%0A%23%20the%20%22parent-hash%22%20attribute%20which%20also%20defines%20an%20association%0A%23%20to%20the%20parent%20device.%20See%20usbguard-rules.conf%285%29%20for%20more%0A%23%20details.%0A%23%0ADeviceRulesWithPort%3Dfalse%0A%0A%23%0A%23%20USBGuard%20Audit%20events%20log%20backend%0A%23%0A%23%20One%20of%3A%0A%23%0A%23%20%2A%20FileAudit%20-%20Log%20audit%20events%20into%20a%20file%20specified%20by%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20AuditFilePath%20setting%20%28see%20below%29%0A%23%20%2A%20LinuxAudit%20-%20Log%20audit%20events%20using%20the%20Linux%20Audit%0A%23%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20subsystem%20%28using%20audit_log_user_message%29%0A%23%0AAuditBackend%3DLinuxAudit%0A%0A%23%0A%23%20USBGuard%20audit%20events%20log%20file%20path.%0A%23%0A%23AuditFilePath%3D/var/log/usbguard/usbguard-audit.log%0A%0A%23%0A%23%20Hides%20personally%20identifiable%20information%20such%20as%20device%20serial%20numbers%20and%0A%23%20hashes%20of%20descriptors%20%28which%20include%20the%20serial%20number%29%20from%20audit%20entries.%0A%23%0A%23HidePII%3Dfalse }}
        mode: 0600
        path: /etc/usbguard/usbguard-daemon.conf
        overwrite: true

# Remediation is applicable only in certain platforms
if ( [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ] && ! grep -q s390x /proc/sys/kernel/osrelease ) && { rpm --quiet -q usbguard; }; then

if [ -e "/etc/usbguard/usbguard-daemon.conf" ] ; then
    
    LC_ALL=C sed -i "/^\s*AuditBackend=/d" "/etc/usbguard/usbguard-daemon.conf"else
    touch "/etc/usbguard/usbguard-daemon.conf"
fi
# make sure file has newline at the end
sed -i -e '$a\' "/etc/usbguard/usbguard-daemon.conf"

cp "/etc/usbguard/usbguard-daemon.conf" "/etc/usbguard/usbguard-daemon.conf.bak"
# Insert at the end of the file
printf '%s\n' "AuditBackend=LinuxAudit" >> "/etc/usbguard/usbguard-daemon.conf"
# Clean up after ourselves.
rm "/etc/usbguard/usbguard-daemon.conf.bak"

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

Log USBGuard daemon audit events using Linux Audit

Description

Rationale

Remediation - Kubernetes Patch

Remediation - Shell Script