CVE-2021-39637 in Android
Summary
by MITRE • 12/15/2021
In CreateDeviceInfo of trusty_remote_provisioning_context.cpp, there is a possible out of bounds read due to a missing bounds check. This could lead to local information disclosure with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-193579873References: N/A
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Analysis
by VulDB Data Team • 12/18/2021
The vulnerability identified as CVE-2021-39637 resides within the trusty_remote_provisioning_context.cpp source file, specifically within the CreateDeviceInfo function implementation. This represents a classic out-of-bounds read flaw that occurs when the system fails to validate array indices or buffer limits before accessing memory locations. The issue manifests as a missing bounds check that should have been implemented to ensure that memory access operations remain within legitimate parameter boundaries. Such vulnerabilities typically arise during development when insufficient input validation is performed on data structures that are subsequently accessed without proper boundary verification.
The technical exploitation of this vulnerability requires an attacker to possess system execution privileges, indicating that the flaw operates at a privileged level within the Android kernel environment. This prerequisite suggests that the vulnerability exists within kernel-space code where the trusty security framework operates, making it particularly concerning as it could potentially allow unauthorized information disclosure. The absence of user interaction requirements for exploitation means that once an attacker has achieved system-level access, they can trigger the vulnerability automatically without needing additional user engagement or specific conditions to be met.
The operational impact of this vulnerability extends beyond simple information disclosure, as it represents a potential pathway for privilege escalation or data exfiltration within the Android security ecosystem. The trusty remote provisioning context suggests this operates within a security-sensitive environment where device provisioning and trust management occur, making the potential information disclosure particularly dangerous. Attackers could potentially extract sensitive data from memory locations that should remain protected, potentially including cryptographic keys, device identifiers, or other security-critical information that could be leveraged for further attacks against the Android device or its connected systems.
This vulnerability aligns with CWE-129, which specifically addresses insufficient validation of length of inputs, and represents a direct violation of secure coding practices that mandate bounds checking for all array and buffer operations. From an ATT&CK perspective, this vulnerability could be categorized under T1059 for system execution privileges and potentially T1068 for local privilege escalation, depending on the specific exploitation chain. The Android ID A-193579873 indicates this was properly tracked within Google's security infrastructure, suggesting the issue was recognized as significant enough to warrant internal tracking and remediation. Mitigation strategies should focus on implementing comprehensive bounds checking mechanisms, conducting thorough code reviews for similar patterns, and ensuring that all memory access operations include proper validation before execution.