CVE-2016-3935 in Android
Summary
by MITRE
Multiple integer overflows in drivers/crypto/msm/qcedev.c in the Qualcomm cryptographic engine driver in Android before 2016-10-05 on Nexus 5X, Nexus 6, Nexus 6P, and Android One devices allow attackers to gain privileges via a crafted application, aka Android internal bug 29999665 and Qualcomm internal bug CR 1046507.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability described in CVE-2016-3935 represents a critical integer overflow flaw within the Qualcomm cryptographic engine driver component of Android operating systems. This issue specifically affects the qcedev.c file in the drivers/crypto/msm/ directory of the Android kernel source tree, targeting devices manufactured by Qualcomm that were shipped with Android versions prior to the security patch released on October 5, 2016. The vulnerability impacts a range of popular Android devices including the Nexus 5X, Nexus 6, Nexus 6P, and Android One models, making it particularly widespread across the mobile ecosystem.
The technical nature of this vulnerability stems from improper input validation within the cryptographic engine driver where integer overflow conditions can occur during the processing of cryptographic operations. When an attacker crafts a malicious application that exploits this flaw, the integer overflow can lead to memory corruption that allows privilege escalation. The vulnerability operates at the kernel level within the Qualcomm MSM (Multi-System Module) cryptographic subsystem, which handles sensitive cryptographic operations for secure communications and data protection. The specific integer overflow conditions in the qcedev.c driver can cause buffer overflows or other memory corruption issues that enable attackers to execute arbitrary code with elevated privileges, effectively bypassing the normal security boundaries between user applications and the kernel.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete control over affected devices. The flaw can be exploited through ordinary applications without requiring physical access or special privileges, making it particularly dangerous for widespread exploitation. The vulnerability's classification aligns with CWE-190, which describes integer overflow conditions, and it maps to ATT&CK technique T1068, which covers exploit for privilege escalation. Attackers can leverage this vulnerability to install malicious applications, access sensitive data, modify system files, or even establish persistent backdoors on affected devices. The fact that this vulnerability affects multiple Nexus and Android One devices indicates a systemic issue within Qualcomm's cryptographic implementation that required coordinated patches across both the Android framework and Qualcomm's proprietary driver components.
Mitigation strategies for CVE-2016-3935 primarily involve applying the security patches released by Google and Qualcomm in their respective security updates. Device users should ensure their systems are updated to Android security patch level 2016-10-05 or later, which contains the necessary fixes for the integer overflow conditions in the qcedev.c driver. Organizations managing fleets of affected devices should prioritize immediate patch deployment and implement monitoring for suspicious application behavior that might indicate exploitation attempts. The vulnerability also highlights the importance of proper input validation in kernel-level cryptographic drivers and serves as a reminder of the critical security implications of integer overflow flaws in security-sensitive components. Additionally, system administrators should consider implementing application whitelisting policies and network monitoring to detect potential exploitation attempts, particularly focusing on applications that might attempt to access the Qualcomm cryptographic engine directly.