CVE-2022-1665: Red Hat Enterprise Linux Auth Bypass Flaw

CVE-2022-1665 Overview

A Secure Boot bypass vulnerability exists in pre-production kernel packages of Red Hat Enterprise Linux for IBM Power architecture. These kernel builds can be booted by GRUB in Secure Boot mode despite lacking the necessary secure boot lockdown patches. This allows attackers to bypass secure boot validations and load untrusted code onto affected systems.

Critical Impact

Attackers with local access and high privileges can bypass Secure Boot protections, potentially loading malicious code that persists across reboots and evades traditional security controls.

Affected Products

• Red Hat Enterprise Linux 8.0 (IBM Power architecture)
• Pre-production kernel packages for RHEL on ppc64le

Discovery Timeline

• 2022-06-21 - CVE-2022-1665 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-1665

Vulnerability Analysis

This vulnerability falls into the category of Secure Boot Bypass and relates to CWE-1291 (Public Key Re-Use for Signing Both Debug and Production Code). The core issue stems from pre-production kernel packages being improperly signed in a way that allows GRUB to boot them in Secure Boot mode, even though these kernels lack the critical secure boot lockdown patches.

When Secure Boot is enabled, the system firmware validates the bootloader and kernel signatures before execution. However, the affected pre-production kernels pass this validation despite missing the lockdown patches that would normally prevent unauthorized access to sensitive kernel interfaces. This creates a dangerous gap where an attacker can leverage these improperly secured kernels as a bridge to load additional untrusted code.

The attack requires local access with high privileges. However, if successfully exploited, the impact extends beyond the initial system boundaries due to the scope change characteristic—an attacker could potentially affect other components or systems that rely on the integrity guarantees that Secure Boot is supposed to provide.

Root Cause

The root cause of this vulnerability is a failure in the build and signing process for pre-production kernel packages on the IBM Power (ppc64le) architecture. These kernel packages were signed with valid production keys but did not include the secure boot lockdown patches. This allowed the kernels to pass signature verification during the Secure Boot process while lacking the runtime protections that prevent loading of unsigned kernel modules and direct hardware access.

Attack Vector

The attack vector is local, requiring the attacker to have high-privileged access to the target system. The exploitation process involves:

1. Obtaining or placing the vulnerable pre-production kernel packages on the target system
2. Configuring GRUB to boot the vulnerable kernel
3. Bypassing Secure Boot validations due to the kernel's valid signature
4. Exploiting the missing lockdown patches to load unsigned kernel modules or access restricted kernel interfaces
5. Installing persistent malicious code that operates below the operating system level

The vulnerability is particularly concerning because it undermines the trust chain that Secure Boot is designed to establish, potentially allowing rootkit-level persistence.

Detection Methods for CVE-2022-1665

Indicators of Compromise

• Presence of pre-production or non-standard kernel packages on IBM Power architecture systems
• Unexpected kernel versions that don't match official RHEL releases
• Unsigned or improperly signed kernel modules loaded on systems with Secure Boot enabled
• Modified GRUB configuration pointing to non-standard kernel images

Detection Strategies

• Audit installed kernel packages using rpm -qa | grep kernel and verify against official Red Hat package manifests
• Monitor GRUB configuration files (/etc/default/grub, /boot/grub2/grub.cfg) for unauthorized changes
• Implement file integrity monitoring on boot-related directories (/boot, /boot/efi)
• Use SentinelOne Singularity Platform to detect anomalous boot sequences and kernel module loading behavior

Monitoring Recommendations

• Enable kernel audit logging to track module loading events via auditctl -w /sbin/modprobe -p x -k kernel_modules
• Configure alerts for changes to boot partition files and GRUB configurations
• Monitor for kernel version changes or unexpected reboots to non-standard kernels
• Leverage SentinelOne's deep visibility into kernel-level activity for real-time threat detection

How to Mitigate CVE-2022-1665

Immediate Actions Required

• Inventory all Red Hat Enterprise Linux systems on IBM Power architecture and identify any pre-production kernel packages
• Remove any pre-production kernel packages and replace them with official production releases from Red Hat
• Verify Secure Boot is properly configured and test that only authorized kernels can boot
• Review GRUB configuration to ensure only approved kernel images are listed

Patch Information

Red Hat has addressed this vulnerability through proper production kernel releases that include the secure boot lockdown patches. Administrators should update to the latest officially released RHEL 8 kernel packages for IBM Power architecture. Detailed information about the fix is available in Red Hat Bug Report #2089529.

To update to patched kernel packages:

# Update to latest kernel packages
sudo dnf update kernel kernel-core kernel-modules

# Verify installed kernel version
rpm -qa | grep kernel

# Regenerate GRUB configuration
sudo grub2-mkconfig -o /boot/grub2/grub.cfg

# Reboot to apply updated kernel
sudo systemctl reboot

Workarounds

• Restrict physical and administrative access to IBM Power systems running RHEL to trusted personnel only
• Implement strict package management policies that prevent installation of non-production kernel packages
• Use Red Hat Satellite or similar tools to enforce compliance with approved kernel versions across the environment
• Enable UEFI Secure Boot database auditing where supported to detect unauthorized signing key usage

# Configuration example
# Verify Secure Boot status
mokutil --sb-state

# List enrolled Secure Boot keys
mokutil --list-enrolled

# Ensure only official RHEL kernels are installed
rpm -qa --qf '%{NAME}-%{VERSION}-%{RELEASE}.%{ARCH} %{SIGPGP:pgpsig}\n' | grep kernel

# Lock kernel packages to prevent accidental downgrades
sudo dnf versionlock add kernel kernel-core kernel-modules