CVE-2023-28746 Overview
CVE-2023-28746 is a hardware-level information disclosure vulnerability affecting certain Intel Atom processors. The vulnerability enables information exposure through microarchitectural state after transient execution from some register files. An authenticated local user can potentially exploit this flaw to access sensitive information that should be protected, representing a significant risk in multi-tenant and virtualized environments.
Critical Impact
Authenticated local users may extract sensitive data from microarchitectural state, potentially compromising cryptographic keys, credentials, or other privileged information from co-located processes or virtual machines.
Affected Products
- Intel Atom Processors (various models as specified in Intel SA-00898)
- Systems running affected processors with Xen hypervisor
- Linux-based systems with affected Intel Atom CPUs
Discovery Timeline
- 2024-03-14 - CVE CVE-2023-28746 published to NVD
- 2025-04-26 - Last updated in NVD database
Technical Details for CVE-2023-28746
Vulnerability Analysis
This vulnerability belongs to the class of transient execution side-channel attacks that have affected modern processors since the disclosure of Spectre and Meltdown. The core issue stems from how Intel Atom processors handle register file states during speculative execution. When the processor speculatively executes instructions, data from register files may leave traces in the microarchitectural state that persist even after the speculative execution is rolled back.
The vulnerability is classified under CWE-1342 (Information Exposure through Microarchitectural State after Transient Execution), which specifically addresses side-channel leakage through CPU microarchitectural components following transient or speculative operations.
In practical terms, an attacker with local access and valid credentials can craft specific instruction sequences that trigger transient execution paths. By carefully measuring timing differences or observing other side effects, the attacker can infer the contents of register files that were accessed during speculative execution, even if those registers belong to other processes or privilege levels.
Root Cause
The root cause lies in the microarchitectural design of affected Intel Atom processors, where register file contents are not properly cleared or isolated during transient execution. When the CPU speculatively executes instructions before determining if a branch is correctly predicted, data from register files can influence observable microarchitectural state (such as cache contents). This state persists and can be measured by an attacker even after the speculative execution results are discarded.
Attack Vector
The attack requires local access with authenticated user privileges. An attacker must execute carefully crafted code on the target system to exploit the vulnerability. The attack does not require user interaction and can affect confidentiality across security boundaries, potentially allowing extraction of data from other processes, containers, or virtual machines running on the same physical processor. This is particularly concerning in cloud and virtualization environments where multiple tenants share the same hardware.
The attacker would typically:
- Execute code that triggers specific transient execution paths
- Prime microarchitectural structures (such as caches) to a known state
- Cause the target to access sensitive data during transient execution
- Measure side effects in the microarchitectural state to infer the sensitive data
The vulnerability does not directly enable data modification or denial of service—it is purely an information disclosure issue with confidentiality impact across security contexts.
Detection Methods for CVE-2023-28746
Indicators of Compromise
- Unusual patterns of cache timing measurements from user-space processes
- Processes repeatedly executing specific instruction sequences designed to trigger transient execution
- Abnormal system call patterns associated with microarchitectural side-channel attacks
Detection Strategies
- Monitor for processes performing high-resolution timing measurements using rdtsc or similar instructions
- Implement behavioral analysis to detect characteristic patterns of transient execution attacks
- Use hardware performance counters to identify unusual speculation patterns on affected processors
Monitoring Recommendations
- Deploy endpoint detection and response (EDR) solutions capable of detecting side-channel attack behavior
- Monitor for known exploitation tools or techniques targeting Intel processor vulnerabilities
- Audit local user activities on systems with affected Intel Atom processors, particularly in multi-tenant environments
How to Mitigate CVE-2023-28746
Immediate Actions Required
- Apply microcode updates from Intel as specified in Intel Security Advisory SA-00898
- Update operating system kernels with vendor-provided patches (see Debian and Fedora advisories)
- For Xen hypervisor environments, apply patches referenced in Xen Security Advisory XSA-452
- Review and limit local user access on systems processing sensitive information
Patch Information
Intel has released microcode updates to address this vulnerability, documented in Intel Security Advisory SA-00898. Operating system vendors including Debian and Fedora have released kernel updates that incorporate necessary mitigations. Organizations should apply both CPU microcode updates and operating system patches for comprehensive protection.
Relevant security updates are available from:
Workarounds
- Restrict local access to affected systems to only trusted users
- Implement process isolation using containers or VMs with appropriate security configurations
- Consider disabling simultaneous multithreading (SMT/Hyper-Threading) if available on affected processors
- Monitor the Intel Security Center for additional guidance and firmware updates
# Example: Check Intel microcode version on Linux
cat /proc/cpuinfo | grep -E "model name|microcode"
# Example: Update microcode on Debian-based systems
sudo apt update && sudo apt install intel-microcode
# Example: Verify kernel mitigations are active
cat /sys/devices/system/cpu/vulnerabilities/*
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
