CVE-2020-0408 in Android
Summary
by MITRE • 10/14/2020
In remove of String16.cpp, 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-11 Android-8.0 Android-8.1 Android-9 Android-10Android ID: A-156999009
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/19/2020
The vulnerability identified as CVE-2020-0408 resides within the String16.cpp implementation of Android's platform, specifically in the remove function where a critical integer overflow occurs. This flaw represents a classic buffer management issue that can be exploited to execute arbitrary code with elevated privileges. The vulnerability affects multiple Android versions including Android 8.0, 8.1, 9, 10, and 11, indicating a widespread impact across the Android ecosystem. The integer overflow occurs during the calculation of memory boundaries when processing string operations, creating a scenario where an attacker can manipulate input data to cause memory corruption. This type of vulnerability falls under CWE-190, which specifically addresses integer overflow conditions that can lead to buffer overflows and memory corruption. The exploitability of this vulnerability is particularly concerning because it requires no user interaction and can be leveraged for local privilege escalation without additional execution privileges, making it a significant threat to Android device security.
The technical flaw manifests when the remove function processes string data and performs arithmetic operations on integer values that can exceed the maximum representable value for the data type being used. This overflow condition results in incorrect memory calculations, allowing an attacker to write data beyond the intended buffer boundaries. The vulnerability is particularly dangerous because it operates at the system level where it can manipulate memory structures that control critical system functions. When an integer overflow occurs in memory management operations, it can corrupt adjacent memory locations, potentially overwriting critical control structures, function pointers, or other essential data elements. The flaw demonstrates how seemingly benign string operations can become attack vectors when proper integer overflow protections are absent. This vulnerability aligns with ATT&CK technique T1068 which describes the exploitation of system vulnerabilities for privilege escalation, and T1059 which covers the use of system commands and APIs to execute malicious code. The integer overflow creates a predictable pattern of memory corruption that can be systematically exploited to gain elevated privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially compromise the entire Android security model. An attacker who successfully exploits this vulnerability can gain root access to the device, enabling them to modify system files, install malicious applications, access all user data, and potentially create persistent backdoors. The lack of user interaction requirements means that exploitation can occur automatically when the vulnerable system processes specific string data, making it particularly dangerous in real-world scenarios. The vulnerability affects core Android functionality since String16.cpp is part of the fundamental string handling libraries used throughout the operating system. This means that any application or system process that handles string data can potentially be exploited, creating a broad attack surface. The impact is especially severe in enterprise environments where Android devices may be used for sensitive data processing, as the privilege escalation could allow attackers to access confidential corporate information or disrupt critical business operations.
Mitigation strategies for CVE-2020-0408 should focus on immediate patch deployment through Android security updates, which typically include bounds checking mechanisms and integer overflow protections. Organizations should ensure all Android devices are updated to the latest security patches released by Google, particularly those addressing integer overflow conditions in system libraries. System administrators should implement monitoring solutions to detect unusual memory access patterns that might indicate exploitation attempts, and consider implementing additional security controls such as address space layout randomization and stack canaries to make exploitation more difficult. The vulnerability highlights the importance of robust input validation and proper integer handling in system-level code, emphasizing the need for code reviews that specifically address integer overflow conditions. Security teams should also consider implementing application whitelisting and device hardening measures to reduce the attack surface. For organizations unable to immediately deploy patches, temporary workarounds such as restricting access to potentially vulnerable applications or implementing network-level controls may be necessary. The vulnerability serves as a reminder of the critical importance of secure coding practices and the need for comprehensive security testing of system libraries that handle memory operations.