CVE-2016-3901 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 29999161 and Qualcomm internal bug CR 1046434.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability identified as CVE-2016-3901 represents a critical integer overflow condition within the Qualcomm cryptographic engine driver component of Android operating systems. This flaw exists specifically in the qcedev.c file located within the drivers/crypto/msm/ directory of the Android kernel source tree, affecting devices manufactured by Google and Qualcomm that utilize the MSM (Mobile Station Modem) cryptographic engine. The vulnerability impacts a range of Nexus and Android One devices including the Nexus 5X, Nexus 6, Nexus 6P, and related hardware platforms that shipped with Android versions prior to the 2016-10-05 security update.
The technical nature of this vulnerability stems from improper input validation within the cryptographic driver's handling of integer values during cryptographic operations. When a malicious application submits crafted parameters to the Qualcomm cryptographic engine, the driver fails to properly validate integer boundaries, leading to arithmetic overflow conditions. These overflow scenarios can result in memory corruption, where the overflowed integer values cause unexpected behavior in memory allocation or buffer handling within the kernel space. The flaw is classified under CWE-190 as an integer overflow or wraparound, specifically manifesting in the context of cryptographic operations where integer values control buffer sizes, loop counters, or memory allocation parameters.
The operational impact of this vulnerability is severe and directly enables privilege escalation attacks. An attacker with a malicious application running on an affected device can exploit this integer overflow to execute arbitrary code with kernel-level privileges, effectively bypassing Android's security model and gaining full system control. The attack vector requires only a locally installed application, making it particularly dangerous as it can be triggered through seemingly benign software installations or updates. This vulnerability allows attackers to escalate from regular application privileges to root access, potentially enabling complete system compromise including data theft, persistent backdoor installation, and modification of critical system components. The exploitation process aligns with ATT&CK technique T1068 which describes the use of privilege escalation techniques through kernel vulnerabilities.
Mitigation strategies for CVE-2016-3901 primarily involve applying the security patches released by Google and Qualcomm as part of their regular Android security updates. Device owners should ensure their Nexus 5X, Nexus 6, Nexus 6P, and Android One devices receive the October 2016 security update or subsequent releases that contain the patched qcedev.c driver implementation. The fix typically involves implementing proper integer boundary checks and input validation within the cryptographic driver to prevent overflow conditions from occurring during parameter processing. Organizations managing fleets of affected devices should prioritize immediate deployment of these patches and consider implementing additional security monitoring to detect potential exploitation attempts. System administrators should also review application installation policies to limit the potential attack surface, as the vulnerability requires only a locally installed application to be triggered. The patched implementation should include robust error handling and validation mechanisms that prevent malicious inputs from causing integer overflows, thereby maintaining the integrity of the cryptographic engine's memory management and preventing unauthorized privilege escalation.