CVE-2021-39722 in Android
Summary
by MITRE • 03/16/2022
In ProtocolStkProactiveCommandAdapter::Init of protocolstkadapter.cpp, there is a possible out of bounds read due to an incorrect 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-204585345References: N/A
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Analysis
by VulDB Data Team • 03/19/2022
The vulnerability identified as CVE-2021-39722 represents a critical out-of-bounds read condition within the Android kernel's protocol stack implementation, specifically affecting the ProtocolStkProactiveCommandAdapter::Init function in the protocolstkadapter.cpp source file. This flaw resides in the telephony subsystem's handling of proactive commands, which are essential for SIM card communication and mobile network operations. The issue manifests when the system processes certain proactive command data structures without proper validation of array boundaries, creating a potential pathway for unauthorized data access.
The technical implementation flaw stems from an inadequate bounds check mechanism that fails to properly validate the size of incoming data before attempting to read from memory locations. This particular vulnerability falls under CWE-129, which specifically addresses insufficient bounds checking, and more broadly relates to CWE-787, concerning out-of-bounds write operations that can result in information disclosure. The improper validation allows an attacker to manipulate the data processing flow and potentially access memory regions that should remain protected, particularly when the system executes with system-level privileges.
From an operational perspective, this vulnerability presents a significant risk as it requires only system execution privileges to exploit, meaning that an attacker with minimal access to the device can potentially extract sensitive information from the kernel memory space. The local information disclosure threat is particularly concerning because it could expose confidential data such as SIM card authentication tokens, network credentials, or other sensitive telephony-related information. This vulnerability directly impacts Android devices that utilize the affected protocol stack components, potentially compromising the security of mobile communications and user privacy.
The exploitation of this vulnerability aligns with ATT&CK technique T1059.001, which covers command and scripting interpreter usage, as the attacker could potentially leverage this information disclosure to gain further insights into the system's internal operations. Additionally, the vulnerability could enable privilege escalation or lateral movement within the device's security boundaries, as the leaked information might reveal internal system structures or authentication mechanisms. The attack surface is particularly relevant for mobile devices where the kernel operates with elevated privileges and where SIM card communication is essential for network connectivity.
Mitigation strategies should focus on implementing proper bounds checking mechanisms within the affected codebase, ensuring that all array accesses are validated against their declared sizes before any memory operations occur. Android security patches typically address this by modifying the protocolstkadapter.cpp file to include comprehensive input validation and boundary checks. Organizations should prioritize applying the latest security updates from Google and device manufacturers, as these patches specifically target the bounds checking deficiency. Additionally, system administrators should monitor for any suspicious network activity or unauthorized access attempts that might indicate exploitation attempts, and consider implementing additional runtime protections such as address space layout randomization and stack canaries to further reduce the exploitability of similar vulnerabilities.