CVE-2020-0369 in Android
Summary
by MITRE
In libavb, there is a possible out of bounds write due to an integer overflow. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-130231426
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 09/18/2020
The vulnerability identified as CVE-2020-0369 resides within the Android Verified Boot (AVB) library known as libavb, which plays a critical role in ensuring the integrity and authenticity of Android system images. This flaw represents a serious security concern as it enables local privilege escalation without requiring any additional execution privileges or user interaction, making it particularly dangerous in threat scenarios where attackers seek to elevate their privileges on compromised devices. The vulnerability manifests through an integer overflow condition that occurs during the processing of verified boot components, specifically affecting the Android 11 operating system version where the issue was documented under Android ID A-130231426.
The technical flaw stems from an integer overflow within the libavb library's handling of certain data structures during the verification process. When processing boot images or system components, the library performs calculations that can result in integer overflows, leading to improper memory allocation and subsequent out-of-bounds write operations. This overflow condition occurs during the parsing of AVB (Android Verified Boot) metadata, where the library fails to properly validate integer values before using them in memory allocation calculations. The vulnerability can be exploited by an attacker with local access to the device who can manipulate the input data to trigger the overflow, causing the program to write data beyond the allocated memory boundaries.
The operational impact of this vulnerability extends beyond simple privilege escalation as it represents a complete breakdown in the Android security model's integrity verification mechanisms. An attacker who successfully exploits this vulnerability can gain root-level privileges on the device without requiring any additional attack vectors or user interaction, effectively bypassing the fundamental security protections that AVB is designed to provide. The lack of user interaction requirement makes this particularly concerning as it can be exploited silently in the background, potentially allowing for persistent access and control over the device. This vulnerability directly undermines the core security principle of verified boot by enabling malicious code execution at the system level.
The exploitation of CVE-2020-0369 aligns with tactics described in the ATT&CK framework under privilege escalation techniques, specifically targeting the execution of malicious code with elevated privileges. From a CWE perspective, this vulnerability maps to CWE-190, which addresses integer overflow conditions, and CWE-787, which covers out-of-bounds write operations. The vulnerability's classification as a local privilege escalation issue places it within the broader category of system-level attacks that can compromise the entire device. The integer overflow in libavb creates a predictable pattern that can be leveraged by attackers to manipulate memory layout and potentially execute arbitrary code with system-level privileges.
Mitigation strategies for this vulnerability primarily involve applying the latest security patches and updates provided by Google and device manufacturers, as the issue was addressed through firmware and system updates. Organizations should ensure that all Android 11 devices are updated with the latest security patches, particularly those related to AVB and verified boot components. Additionally, implementing network monitoring and endpoint detection capabilities can help identify potential exploitation attempts by monitoring for unusual memory access patterns or privilege escalation activities. Device administrators should also consider implementing additional security controls such as application whitelisting and enhanced logging mechanisms to detect and prevent exploitation attempts. The vulnerability's nature makes it particularly important to maintain up-to-date security configurations and to monitor for any signs of unauthorized privilege escalation attempts on affected devices.