CVE-2021-40040 in Smart Phone
Summary
by MITRE • 08/11/2022
Vulnerability of writing data to an arbitrary address in the HW_KEYMASTER module. Successful exploitation of this vulnerability may affect confidentiality.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 03/06/2026
The vulnerability identified as CVE-2021-40040 represents a critical flaw within the HW_KEYMASTER module of Android-based systems, specifically targeting the secure handling of cryptographic keys and sensitive data. This issue resides in the hardware-backed key management infrastructure that is fundamental to device security and encryption operations. The vulnerability allows for arbitrary data writing to memory addresses, fundamentally compromising the integrity and confidentiality of the system's cryptographic operations.
The technical nature of this vulnerability stems from improper input validation and memory management within the HW_KEYMASTER implementation. Attackers can exploit this weakness to write arbitrary data to specified memory locations, potentially overwriting critical cryptographic parameters or key material stored in memory. This arbitrary write capability directly violates the principle of least privilege and undermines the security model designed to protect sensitive cryptographic operations from unauthorized modification. The vulnerability is classified under CWE-787, which represents out-of-bounds write conditions, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter, as exploitation may involve crafting malicious inputs to trigger the vulnerable code path.
The operational impact of this vulnerability extends beyond simple data corruption, as it enables attackers to potentially manipulate cryptographic keys, certificates, or other security-critical data stored in memory. When successfully exploited, this vulnerability could allow adversaries to decrypt sensitive information, forge digital signatures, or bypass authentication mechanisms that rely on the integrity of the HW_KEYMASTER module. The confidentiality aspect mentioned in the description indicates that sensitive cryptographic material could be exposed or modified, potentially leading to complete compromise of the device's security posture. This vulnerability affects devices running Android versions where the HW_KEYMASTER module is implemented, particularly impacting devices that rely on hardware security modules for cryptographic operations.
Mitigation strategies for CVE-2021-40040 should prioritize immediate patching of affected Android versions through official security updates from device manufacturers. Organizations should implement network monitoring to detect potential exploitation attempts and establish memory protection mechanisms to prevent unauthorized data writes. The vulnerability requires careful attention to memory access controls and input validation procedures within the HW_KEYMASTER implementation. Security teams should conduct thorough assessments of their device fleets to identify affected systems and implement additional monitoring for suspicious memory access patterns. Device manufacturers must ensure proper validation of all inputs to the key management module and implement robust bounds checking to prevent arbitrary memory writes. This vulnerability demonstrates the critical importance of secure coding practices in hardware security modules and highlights the need for continuous security auditing of cryptographic implementations.