CVE-2021-28210 in EDK II
Summary
by MITRE • 06/11/2021
An unlimited recursion in DxeCore in EDK II.
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Analysis
by VulDB Data Team • 10/11/2024
The vulnerability identified as CVE-2021-28210 represents a critical recursive flaw within the DxeCore component of the EDK II firmware development environment. This issue manifests as unlimited recursion in the DXE (Driver Execution Environment) core module, which serves as the foundational runtime environment for UEFI firmware implementations. The flaw exists within the firmware's initialization and execution flow where improper bounds checking or termination conditions allow recursive function calls to continue indefinitely without proper stack management or recursion depth limits. This vulnerability specifically impacts systems that utilize EDK II as their firmware development framework, including various enterprise servers, workstations, and embedded systems that rely on UEFI-based boot processes.
The technical implementation of this vulnerability stems from inadequate control flow management within the DxeCore's internal function execution pathways. When certain initialization routines or driver loading sequences are triggered, the code fails to implement proper recursion depth monitoring or stack overflow protection mechanisms. This allows malicious actors or faulty firmware components to exploit the recursive behavior by repeatedly invoking functions that ultimately call themselves without proper termination conditions. The flaw operates at the firmware level, making it particularly dangerous as it can persist through the entire boot process and potentially compromise system integrity before the operating system even loads. This type of vulnerability falls under CWE-674, which specifically addresses Uncontrolled Recursion, and aligns with ATT&CK technique T1068 by providing an execution pathway that can be leveraged for privilege escalation or system compromise.
The operational impact of CVE-2021-28210 extends beyond simple system instability, as it creates potential entry points for sophisticated attacks targeting firmware integrity. Systems running affected EDK II implementations may experience complete system hangs, reboot loops, or in more severe cases, allow attackers to execute arbitrary code during the firmware initialization phase. The vulnerability is particularly concerning in enterprise environments where firmware updates may be infrequent or where legacy systems continue to operate with vulnerable firmware components. Attackers could potentially leverage this recursion flaw to bypass security measures that depend on proper firmware execution, as the infinite recursion would prevent normal system operation and could be used to mask other malicious activities. The impact is amplified because firmware-level vulnerabilities are notoriously difficult to detect and remediate, often requiring complete system replacement or specialized firmware update procedures.
Mitigation strategies for CVE-2021-28210 require immediate attention from system administrators and firmware developers working with EDK II environments. The most effective approach involves applying the official patches provided by the EDK II project maintainers, which typically include enhanced recursion depth checking and proper termination conditions for all core execution functions. Organizations should also implement firmware integrity monitoring solutions that can detect anomalous execution patterns indicative of recursive behavior. Regular firmware audits and vulnerability assessments should be conducted to identify systems running affected EDK II versions, with priority given to critical infrastructure components. Additionally, implementing proper code review processes that include recursion analysis and stack depth validation can prevent similar issues from emerging in future firmware development cycles. The vulnerability demonstrates the importance of adhering to secure coding practices and comprehensive testing procedures for firmware components, particularly those operating in critical system initialization phases where errors can have cascading effects on overall system security and stability.