CVE-2021-28211 in EDK II
Summary
by MITRE • 06/11/2021
A heap overflow in LzmaUefiDecompressGetInfo function in EDK II.
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Analysis
by VulDB Data Team • 10/11/2024
The heap overflow vulnerability identified as CVE-2021-28211 resides within the LzmaUefiDecompressGetInfo function of the EDK II firmware development environment. This flaw represents a critical security issue that can potentially compromise the integrity and stability of UEFI-based systems. The vulnerability manifests when processing compressed data streams, specifically in the decompression logic that handles LZMA compressed firmware images. The issue stems from inadequate bounds checking during the decompression process, allowing maliciously crafted compressed data to overwrite adjacent heap memory regions. This type of vulnerability falls under the category of buffer overflow conditions as classified by CWE-121, specifically CWE-787 which denotes out-of-bounds write operations. The vulnerability affects systems that rely on EDK II for firmware development and UEFI implementation, including various enterprise servers, desktop computers, and embedded devices that utilize UEFI firmware for boot processes.
The technical exploitation of this vulnerability occurs when an attacker crafts a specially formatted LZMA compressed data stream that triggers the heap overflow during decompression. The LzmaUefiDecompressGetInfo function fails to properly validate the size parameters of the compressed data before attempting to allocate memory for decompression operations. When the decompression routine processes malformed input data, it can cause the heap memory allocation to exceed the intended buffer boundaries, resulting in memory corruption that may allow arbitrary code execution. This vulnerability is particularly dangerous in UEFI environments where firmware code operates with high privileges and has direct access to system hardware. The attack vector typically involves manipulating firmware update processes, boot loaders, or system recovery mechanisms that utilize the vulnerable decompression function. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, as successful exploitation could lead to firmware-level code execution and system compromise.
The operational impact of CVE-2021-28211 extends beyond simple memory corruption, potentially enabling attackers to achieve complete system compromise through firmware-level attacks. An attacker who successfully exploits this vulnerability could gain persistent control over affected systems by modifying firmware components, creating backdoors, or injecting malicious code into the boot process. The vulnerability affects the integrity of the UEFI firmware stack, which serves as a critical security foundation for modern computing systems. Systems utilizing EDK II components for firmware development are at risk, particularly those that process untrusted firmware images or allow external firmware updates. The exploitation of this vulnerability can lead to persistent rootkits, hardware-level attacks, and complete system takeover. Organizations running affected systems may experience unauthorized access to sensitive data, system availability issues, and potential data exfiltration through modified firmware components. The impact is especially severe in enterprise environments where firmware integrity is crucial for maintaining security postures and preventing advanced persistent threats. According to industry best practices, this vulnerability requires immediate attention and remediation through firmware updates, code patches, and comprehensive security assessments of affected UEFI implementations.
Mitigation strategies for CVE-2021-28211 should focus on both immediate remediation and long-term security hardening measures. Organizations should prioritize updating their EDK II implementations to versions that contain the necessary patches for the vulnerable decompression function. The patch implementation addresses the insufficient bounds checking by adding proper validation of compressed data parameters before memory allocation occurs. Additionally, system administrators should implement firmware integrity monitoring solutions that can detect unauthorized modifications to UEFI firmware components. Security controls should include enabling Secure Boot mechanisms, implementing firmware update validation procedures, and establishing robust firmware change management processes. Network segmentation and access controls should be strengthened to limit potential attack vectors that could lead to firmware exploitation. Organizations should also conduct comprehensive vulnerability assessments to identify all systems that utilize affected EDK II components and ensure proper patch deployment across their entire infrastructure. The mitigation approach aligns with NIST SP 800-171 requirements for protecting controlled unclassified information and follows the principle of least privilege for firmware operations. Regular security audits and firmware integrity checks should be established as ongoing measures to prevent future exploitation attempts targeting similar vulnerabilities in firmware development environments.