CVE-2021-0646 in Android
Summary
by MITRE • 08/17/2021
In sqlite3_str_vappendf of sqlite3.c, there is a possible out of bounds write due to improper input validation. This could lead to local escalation of privilege if the user can also inject a printf into a privileged process's SQL with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-9 Android-10 Android-11 Android-8.1Android ID: A-153352319
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Analysis
by VulDB Data Team • 08/20/2021
The vulnerability identified as CVE-2021-0646 resides within the SQLite database engine's implementation of the sqlite3_str_vappendf function in sqlite3.c. This flaw represents a critical out-of-bounds write condition that arises from inadequate input validation mechanisms. The vulnerability manifests when the SQLite library processes formatted string arguments, specifically within the context of SQL query construction where printf-style formatting is employed. The improper validation allows malicious input to potentially overwrite adjacent memory regions beyond the intended buffer boundaries.
This vulnerability operates at the intersection of memory safety and privilege escalation within Android's database processing framework. The flaw occurs during the execution of SQL operations where printf-style formatting is utilized to construct dynamic queries. When an attacker can influence the input parameters passed to sqlite3_str_vappendf, they can potentially craft malicious payloads that trigger the out-of-bounds write condition. The vulnerability's classification under CWE-121 indicates a weakness in the handling of stack-based buffer operations where data is written beyond allocated memory boundaries. The attack vector is particularly concerning because it requires no user interaction for exploitation, making it a latent threat that can be triggered through automated means.
The operational impact of CVE-2021-0646 extends significantly beyond typical database vulnerabilities due to its potential for local privilege escalation. Android versions affected include Android 8.1, 9, 10, and 11, representing a substantial portion of the mobile ecosystem. The vulnerability's exploitation can result in complete system compromise when an attacker can inject printf-style formatting into SQL queries executed by privileged processes. This scenario is particularly dangerous because it allows for elevation of privileges without requiring additional execution privileges, effectively bypassing standard security boundaries. The Android ID A-153352319 confirms the severity and tracking of this vulnerability within Google's security infrastructure, highlighting its potential for widespread exploitation across multiple Android versions.
The mitigation strategies for CVE-2021-0646 primarily focus on implementing robust input validation and boundary checking within the SQLite library's string formatting functions. System administrators should prioritize applying the latest security patches from Android vendors, as the vulnerability affects core operating system components. Additionally, implementing proper input sanitization at the application level can help prevent malicious payloads from reaching the vulnerable SQLite functions. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the execution of code with elevated privileges. Organizations should also consider implementing runtime monitoring and anomaly detection systems that can identify suspicious patterns in SQL query construction. Regular security audits of database operations and input handling mechanisms remain crucial in preventing exploitation of similar buffer overflow vulnerabilities. The vulnerability's nature suggests that defensive measures should include memory protection mechanisms such as stack canaries and address space layout randomization to mitigate potential exploitation attempts.