CVE-2016-3922 in Android
Summary
by MITRE
libril/RilSapSocket.cpp in Telephony in Android 6.x before 2016-10-01 and 7.0 before 2016-10-01 relies on variable-length arrays, which allows attackers to gain privileges via a crafted application, aka internal bug 30202619.
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Analysis
by VulDB Data Team • 05/01/2019
The vulnerability identified as CVE-2016-3922 resides within the telephony subsystem of Android operating systems, specifically in the libril/RilSapSocket.cpp component that handles communication with cellular network services. This flaw affects Android versions 6.x prior to October 1, 2016, and Android 7.0 before the same date, representing a critical privilege escalation vulnerability that could be exploited by malicious applications. The vulnerability stems from the improper handling of variable-length arrays within the RIL (Radio Interface Layer) SAP (Service Application Programming) socket implementation, which forms part of the core telephony framework responsible for managing cellular connections and network communication.
The technical exploitation of this vulnerability occurs through the use of variable-length arrays that are not properly validated or constrained in memory allocation. When an attacker crafts a malicious application that triggers the vulnerable code path, the system processes these unvalidated arrays without proper bounds checking, leading to potential memory corruption scenarios. This memory corruption can be leveraged to execute arbitrary code with elevated privileges, effectively allowing the malicious application to bypass normal security restrictions and gain access to system-level capabilities. The vulnerability specifically relates to improper memory management where the application fails to validate array sizes before processing, creating opportunities for buffer overflows or other memory corruption conditions that can be exploited to escalate privileges from regular application context to system-level access.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it represents a fundamental flaw in the Android telephony security model that could enable attackers to gain complete control over affected devices. Attackers could potentially use this vulnerability to install malware, access sensitive user data, intercept communications, or modify system configurations without user consent. The vulnerability's exploitation requires only a crafted application, making it particularly dangerous as it could be delivered through standard app distribution channels or via social engineering techniques that trick users into installing malicious software. This makes the vulnerability particularly concerning for enterprise environments where mobile device security is critical, as it could provide attackers with persistent access to corporate networks through compromised employee devices.
Mitigation strategies for CVE-2016-3922 focus primarily on applying the relevant security patches released by Google and device manufacturers, which address the variable-length array handling issue through proper bounds checking and memory validation. Organizations should ensure all Android devices are updated to versions released after October 1, 2016, which contain the necessary fixes for this vulnerability. Additionally, security monitoring should be implemented to detect suspicious application behavior that might indicate attempts to exploit this vulnerability, though such detection is challenging given the sophisticated nature of the attack vector. The vulnerability aligns with CWE-129, which describes improper validation of array index, and represents a significant concern under the ATT&CK framework's privilege escalation techniques, specifically targeting the use of system-level vulnerabilities to gain elevated access rights. Device administrators should also consider implementing application whitelisting policies and restricting the installation of third-party applications to reduce the attack surface available to potential exploiters of this vulnerability.