CVE-2021-39729 in Android
Summary
by MITRE • 03/16/2022
In the TitanM chip, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-202006191References: N/A
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Analysis
by VulDB Data Team • 03/19/2022
The vulnerability identified as CVE-2021-39729 resides within the TitanM chip implementation in Android devices, representing a critical security flaw that undermines system integrity. This issue manifests as an out-of-bounds write condition that occurs when the system fails to perform proper bounds checking on memory operations. The TitanM chip serves as a security processor responsible for handling cryptographic operations and secure boot processes, making its vulnerabilities particularly concerning for overall device security. The absence of bounds validation creates an opportunity for malicious actors to manipulate memory layout and potentially execute arbitrary code with elevated privileges.
The technical nature of this vulnerability aligns with CWE-787, which specifically addresses out-of-bounds write conditions in software systems. This flaw represents a classic buffer overflow scenario where insufficient input validation allows data to be written beyond the allocated memory boundaries. The vulnerability requires system execution privileges for exploitation, indicating that it operates at a privileged level within the kernel space. This requirement suggests that the vulnerability exists within kernel-level components of the Android operating system, specifically within the TitanM chip integration layer where memory management and security operations are handled. The exploitation process would likely involve crafting specific inputs that trigger the memory corruption, potentially leading to privilege escalation.
From an operational perspective, this vulnerability poses significant risks to device security and user privacy. The local privilege escalation capability means that an attacker with access to the device could potentially gain system-level control without requiring user interaction, making it particularly dangerous in environments where physical access is possible. The impact extends beyond individual device compromise to potentially affect entire ecosystems of connected devices that rely on the TitanM chip for security functions. This vulnerability directly relates to the ATT&CK technique T1068, which covers the exploitation of legitimate credentials and system privileges to gain elevated access. The security implications are compounded by the fact that this vulnerability exists within the kernel space, making it difficult to detect and remediate without complete system reinstallation or firmware updates.
Mitigation strategies for CVE-2021-39729 should focus on implementing comprehensive memory bounds checking mechanisms and strengthening the kernel security model. Android device manufacturers should prioritize immediate firmware updates that address the bounds checking deficiency in the TitanM chip implementation. The recommended approach includes applying patches that enforce proper input validation and memory boundary checks within the kernel modules responsible for TitanM operations. Additionally, system administrators should implement monitoring solutions that can detect anomalous memory access patterns indicative of buffer overflow attempts. The mitigation process should also involve reviewing and updating the kernel security configurations to ensure that all memory operations are properly validated before execution. Organizations should conduct thorough security assessments of their Android device fleets to identify vulnerable systems and prioritize remediation efforts based on risk exposure. The solution architecture must incorporate defensive programming practices that prevent similar vulnerabilities from occurring in future implementations, aligning with security standards such as those outlined in the OWASP Secure Coding practices and the CERT Secure Coding Standards.