USN-8267-1: Linux Kernel AppArmor Vulnerabilities (CVE-2026-23268 to CVE-2026-23411) — Detection and Remediation Guide

---
title: Suspicious AppArmor Profile Manipulation
id: a1b2c3d4-e5f6-7890-abcd-ef1234567890
status: experimental
description: Detects potential manipulation of AppArmor profiles by non-root users, which could indicate exploitation of kernel vulnerabilities related to AppArmor LSM.
references:
  - https://ubuntu.com/security/notices/USN-8267-1
author: Security Arsenal
date: 2026/04/28
tags:
  - attack.privilege_escalation
  - attack.t1068
logsource:
  category: process_creation
  product: linux
detection:
  selection:
    CommandLine|contains:
      - 'apparmor_parser'
      - 'aa-disable'
      - 'aa-enforce'
      - 'aa-complain'
  filter:
    User|contains:
      - 'root'
    User|endswith:
      - '0'
  condition: selection and not filter
falsepositives:
  - Legitimate administrative activities by authorized personnel
level: high
---
title: Potential Container Escape via AppArmor Bypass
id: b2c3d4e5-f6a7-8901-bcde-f12345678901
status: experimental
description: Detects potential container escape attempts through suspicious AppArmor profile manipulation or kernel interactions.
references:
  - https://ubuntu.com/security/notices/USN-8267-1
author: Security Arsenal
date: 2026/04/28
tags:
  - attack.execution
  - attack.t1611
logsource:
  category: process_creation
  product: linux
detection:
  container_env:
    Image|contains:
      - '/docker/'
      - '/kubepods/'
      - '/containerd/'
  suspicious_activity:
    CommandLine|contains:
      - 'apparmor_parser'
      - 'mount'
      - 'unshare'
      - 'chroot'
  condition: container_env and suspicious_activity
falsepositives:
  - Legitimate container management activities
level: high

// Hunt for suspicious AppArmor profile manipulation that might indicate exploitation of USN-8267-1
let suspiciousCommands = dynamic(['apparmor_parser', 'aa-disable', 'aa-enforce', 'aa-complain', 'aa-status']);
Syslog
| where ProcessName has_any (suspiciousCommands) or SyslogMessage has_any (suspiciousCommands)
// Focus on AppArmor-related activities
| where SyslogMessage has "apparmor" or SyslogMessage has "AppArmor"
// Identify potential container environments
| extend isContainer = iff(
    ComputerName has "docker" or ComputerName has "containerd" or ComputerName has "k8s" or ComputerName has "kubelet",
    true,
    false
)
// Project relevant fields
| project TimeGenerated, ComputerName, ProcessName, ProcessID, SyslogMessage, isContainer, SeverityLevel
| order by TimeGenerated desc

-- Hunt for suspicious AppArmor profile manipulation
SELECT Pid, Name, CommandLine, Username, Exe
FROM pslist()
WHERE CommandLine =~ 'apparmor_parser'
   OR CommandLine =~ 'aa-disable'
   OR CommandLine =~ 'aa-enforce'
   OR CommandLine =~ 'aa-complain'

-- Check for running containers that might be vulnerable
SELECT Pid, Name, CommandLine, Username
FROM pslist()
WHERE Name =~ 'dockerd'
   OR Name =~ 'containerd'
   OR Name =~ 'kubelet'
   OR Name =~ 'containerd-shim'

-- Check kernel version for vulnerability assessment
SELECT *
FROM execve(argv=['uname', '-r'])
LIMIT 1

#!/bin/bash
# USN-8267-1 Vulnerability Assessment and Remediation Script
# This script checks for Linux kernel vulnerabilities addressed in USN-8267-1

echo "Checking for USN-8267-1 Linux kernel vulnerabilities..."
echo "=========================================================="

# Check current kernel version
echo "Current kernel version: $(uname -r)"

# Check Ubuntu version
echo "Ubuntu version: $(lsb_release -d 2>/dev/null | awk -F'\t' '{print $2}' || echo 'Not an Ubuntu system')"

# Check if AppArmor is installed and enabled
if command -v aa-status &> /dev/null; then
    echo "AppArmor Status:"
    aa-status | head -n 5
else
    echo "AppArmor is not installed or not in path"
fi

# Check for available updates
echo "Checking for available kernel updates..."
apt list --upgradable 2>/dev/null | grep -i linux-image || echo "No available kernel updates found via apt list"

# Recommend remediation
echo ""
echo "RECOMMENDATIONS:"
echo "1. Update to the latest kernel version addressing USN-8267-1:"
echo "   sudo apt update && sudo apt upgrade linux-image-generic"
echo ""
echo "2. After updating, reboot the system:"
echo "   sudo reboot"
echo ""
echo "3. Verify the update:"
echo "   uname -r"
echo ""
echo "4. Check for any AppArmor profile changes:"
echo "   sudo aa-status"
echo ""
echo "For official guidance, refer to: https://ubuntu.com/security/notices/USN-8267-1"