CVE-2021-33103 in Intel
Summary
by MITRE • 05/12/2022
Unintended intermediary in the BIOS authenticated code module for some Intel(R) Processors may allow a privileged user to potentially enable aescalation of privilege via local access.
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Analysis
by VulDB Data Team • 05/16/2022
The vulnerability identified as CVE-2021-33103 resides within the BIOS authenticated code module of certain Intel processors, representing a critical security weakness that could be exploited by privileged users with local access. This flaw specifically targets the authentication mechanisms that are designed to ensure only legitimate firmware components execute within the system's boot process. The issue manifests when the BIOS fails to properly validate the integrity of code modules, creating a potential pathway for malicious actors who already possess elevated privileges to escalate their access rights within the system. The vulnerability falls under the category of privilege escalation, where an attacker with existing local access could leverage this weakness to gain higher-level system privileges that would otherwise be restricted.
The technical nature of this vulnerability stems from improper validation of authenticated code within the BIOS environment, which is a critical component of the system's security architecture. When a processor executes code in a trusted execution environment, the BIOS module should verify that all components are legitimate and have not been tampered with during the boot process. However, in affected Intel processors, this verification mechanism contains a flaw that allows unauthorized code modules to be accepted as valid, thereby undermining the entire security framework. This type of vulnerability is classified as a weakness in the authentication process and aligns with CWE-287 which addresses improper authentication issues in software systems. The flaw essentially creates an unintended intermediary in the code execution chain, where malicious code can be introduced without proper authorization checks.
The operational impact of this vulnerability is significant for organizations relying on Intel processors, particularly in environments where local access might be compromised or where privileged accounts are not adequately protected. A successful exploitation could allow an attacker to bypass security controls that are normally in place to prevent unauthorized access to system resources. The attack vector requires local access and existing privileged user status, which means that while the vulnerability may not be directly exploitable from remote locations, it does pose a substantial risk in scenarios where attackers have already gained some level of system access. This could occur through various means such as insider threats, compromised accounts, or successful phishing attacks that lead to elevated privileges. The potential for privilege escalation through this mechanism could enable attackers to access sensitive system data, modify critical firmware components, or establish persistent access to the system.
Mitigation strategies for CVE-2021-33103 should focus on several key areas including firmware updates from Intel, implementation of robust access controls, and enhanced monitoring of system activities. Organizations should prioritize applying the latest BIOS updates provided by Intel to address the specific authentication flaw within the code module. Additionally, implementing strict access controls and privilege management policies can help reduce the risk of exploitation by limiting the number of users with local access and elevated privileges. System administrators should also enhance monitoring capabilities to detect unusual activities that might indicate attempts to exploit this vulnerability, particularly around BIOS modifications or unauthorized code execution. The mitigation approach should align with established security frameworks and may involve implementing techniques from the MITRE ATT&CK framework, specifically focusing on privilege escalation tactics and defense evasion methods that could be employed by adversaries exploiting this vulnerability. Regular security assessments and vulnerability scanning should be conducted to ensure that systems remain protected against this and similar threats.