CVE-2022-37459 in Altra (Retbleed)
Summary
by MITRE • 08/17/2022
Ampere Altra devices before 1.08g and Ampere Altra Max devices before 2.05a allow attackers to control the predictions for return addresses and potentially hijack code flow to execute arbitrary code via a side-channel attack, aka a "Retbleed" issue.
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Analysis
by VulDB Data Team • 09/17/2022
The CVE-2022-37459 vulnerability represents a critical side-channel attack targeting Ampere Altra and Ampere Altra Max processor architectures, specifically affecting firmware versions prior to 1.08g and 2.05a respectively. This vulnerability falls under the category of speculative execution side-channel attacks that exploit the processor's branch predictor mechanisms to manipulate return address predictions. The flaw enables attackers to potentially hijack code execution flow through a technique known as "Retbleed" which leverages the processor's ability to predict and cache return addresses during speculative execution. The vulnerability stems from insufficient isolation between speculative execution and the processor's prediction mechanisms, creating an attack surface where malicious actors can manipulate the branch predictor to redirect program control flow.
The technical implementation of this vulnerability exploits the processor's return address prediction mechanism, which is designed to improve performance by pre-fetching instructions based on predicted return addresses from function calls. In affected Ampere Altra processors, attackers can manipulate the prediction tables through carefully crafted sequences of branch instructions that cause the processor to mispredict return addresses. This manipulation occurs during speculative execution phases where the processor predicts the outcome of conditional branches and executes instructions before the actual branch resolution. The vulnerability specifically targets the return stack buffer and branch target buffer components that store prediction information, allowing attackers to inject malicious prediction data that influences subsequent code execution paths. The attack vector exploits the fact that the processor's prediction mechanisms do not adequately validate or isolate speculative predictions from potentially malicious inputs.
The operational impact of CVE-2022-37459 is severe as it enables arbitrary code execution without requiring user privileges or direct access to the system. Attackers can leverage this vulnerability to bypass security mitigations such as control flow integrity protections and exploit defenses designed to prevent code injection attacks. The vulnerability is particularly dangerous because it operates at the hardware level within the processor's microarchitecture, making it difficult to detect through traditional software-based security measures. Successful exploitation can lead to complete system compromise, allowing attackers to execute malicious code with the privileges of the compromised process, potentially leading to privilege escalation and persistent backdoor access. The vulnerability affects systems running on Ampere Altra processors including servers, cloud instances, and edge computing devices that rely on these processors for high-performance computing tasks.
Mitigation strategies for CVE-2022-37459 primarily involve firmware updates to the affected Ampere Altra and Altra Max devices, with the recommended firmware versions being 1.08g and 2.05a respectively. Organizations should prioritize immediate firmware upgrades across all affected systems to address the underlying prediction mechanism flaws. Additional mitigations include implementing microcode patches that enhance the isolation between speculative execution and prediction tables, as well as deploying runtime monitoring solutions that can detect anomalous branch prediction behavior. Security teams should also consider implementing application-level protections such as stack canaries and control flow integrity checks, though these measures provide only partial protection against hardware-level vulnerabilities. The vulnerability aligns with CWE-119 (Improper Access to Memory) and CWE-200 (Information Exposure) categories, while its exploitation techniques map to ATT&CK tactics including T1059 (Command and Scripting Interpreter) and T1070 (Indicator Removal on Host) through potential code execution and system compromise. Organizations should conduct comprehensive vulnerability assessments to identify all affected systems and implement layered security controls to reduce the attack surface and prevent exploitation of this critical side-channel vulnerability.