CVE-2024-24853: Intel Processor Privilege Escalation Flaw

CVE-2024-24853 Overview

CVE-2024-24853 is a privilege escalation vulnerability affecting certain Intel processors. The flaw exists in the incorrect behavior order during the transition between the executive monitor and SMI Transfer Monitor (STM). This vulnerability could allow a privileged user to potentially escalate privileges through local access to the affected system.

Critical Impact

A privileged attacker with local access can exploit incorrect execution order in Intel processor SMI Transfer Monitor transitions to escalate privileges beyond their authorized level, potentially gaining complete system control.

Affected Products

• Intel Processors with SMI Transfer Monitor (STM) functionality
• Systems utilizing Intel processor executive monitor transitions
• Firmware implementations affected by STM transition ordering issues

Discovery Timeline

• 2024-08-14 - CVE CVE-2024-24853 published to NVD
• 2024-08-14 - Last updated in NVD database

Technical Details for CVE-2024-24853

Vulnerability Analysis

This vulnerability is classified under CWE-696 (Incorrect Behavior Order), which describes situations where operations are performed in an unexpected or incorrect sequence, leading to security issues. In this case, the vulnerability manifests during the critical transition phase between the executive monitor and the SMI Transfer Monitor (STM) in Intel processors.

The STM is a security component designed to provide isolation and protection for System Management Mode (SMM) code. When transitioning between execution contexts, the processor must follow a strict sequence of operations to maintain security boundaries. The incorrect ordering of these operations creates a window where a privileged attacker can manipulate the system state to escalate their privileges.

The attack requires local access and elevated privileges on the target system, along with specific conditions to be met during the exploitation attempt. Despite these constraints, successful exploitation could result in complete compromise of system confidentiality, integrity, and availability.

Root Cause

The root cause lies in the incorrect behavior order during the transition between the executive monitor and STM components in affected Intel processors. When the execution context switches between these monitors, the sequence of state changes and security checks does not follow the expected secure order. This incorrect sequencing allows an attacker to exploit the timing window created by the out-of-order operations to bypass security controls.

The vulnerability specifically affects the firmware-level handling of monitor transitions, where atomicity and proper ordering are critical for maintaining the security guarantees that SMM and STM are designed to provide.

Attack Vector

The attack vector for CVE-2024-24853 requires local access to the affected system. The attacker must already possess elevated privileges on the target machine. The exploitation chain involves:

1. The attacker identifies a system running on an affected Intel processor with STM functionality
2. With local privileged access, the attacker triggers specific operations that initiate transitions between the executive monitor and STM
3. By manipulating system state during the incorrectly ordered transition sequence, the attacker can escalate privileges beyond their current authorization level
4. Successful exploitation may allow the attacker to execute code in a more privileged context, potentially achieving firmware-level persistence

The vulnerability requires physical or administrative access to the target system, which limits the attack surface but makes the impact particularly severe in scenarios where such access is obtained. For detailed technical specifications, refer to the Intel Security Advisory SA-01083.

Detection Methods for CVE-2024-24853

Indicators of Compromise

• Unexpected SMM-related activity or anomalous System Management Interrupt patterns
• Unusual firmware modification attempts or unauthorized BIOS/UEFI changes
• Privilege escalation events from local administrator accounts to higher privilege levels
• Anomalous memory access patterns during SMI handling operations

Detection Strategies

• Monitor for unauthorized firmware updates or modifications to Intel processor microcode
• Implement hardware-based security monitoring solutions that can detect anomalous SMM behavior
• Enable secure boot and measured boot to detect unauthorized changes to the boot chain
• Deploy endpoint detection solutions capable of monitoring low-level system operations

Monitoring Recommendations

• Configure SIEM rules to alert on unusual local privilege escalation attempts
• Monitor system logs for SMM-related errors or unexpected system management events
• Implement continuous firmware integrity monitoring for critical systems
• Review Intel security advisories and maintain awareness of affected processor models

How to Mitigate CVE-2024-24853

Immediate Actions Required

• Review the Intel Security Advisory SA-01083 to determine if your systems are affected
• Apply available firmware updates from Intel and system vendors as soon as possible
• Restrict local administrative access to affected systems to trusted personnel only
• Implement enhanced monitoring on systems that cannot be immediately patched

Patch Information

Intel has released security updates to address this vulnerability as documented in Intel Security Advisory SA-01083. System administrators should check with their hardware vendors for specific BIOS/UEFI firmware updates that incorporate the Intel microcode fixes. The patches address the incorrect behavior order during STM transitions to ensure proper sequencing of security-critical operations.

Organizations should prioritize patching based on the criticality of affected systems and the level of local access that untrusted users may have. Coordinated deployment with system vendors is recommended to ensure compatibility.

Workarounds

• Limit local administrative access to affected systems until patches can be applied
• Implement strict access controls and privileged access management solutions
• Enable hardware security features such as Secure Boot and Trusted Platform Module (TPM) where available
• Consider network segmentation to isolate affected systems from untrusted users

# Verify current Intel microcode version on Linux systems
cat /proc/cpuinfo | grep -i "microcode"

# Check for available firmware updates
sudo fwupdmgr get-updates

# Apply available firmware updates
sudo fwupdmgr update