CVE-2015-3863 in Android
Summary
by MITRE
Multiple integer overflows in the Blob class in keystore/keystore.cpp in Keystore in Android before 5.1.1 LMY48M allow attackers to execute arbitrary code and read arbitrary Keystore keys via an application that uses a crafted blob in an insert operation, aka internal bug 22802399.
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Analysis
by VulDB Data Team • 01/12/2018
The vulnerability identified as CVE-2015-3863 represents a critical security flaw within the Android Keystore system that affects versions prior to 5.1.1 LMY48M. This issue resides in the Blob class implementation within keystore/keystore.cpp, where multiple integer overflows occur during insert operations. The vulnerability operates at the core of Android's cryptographic key management infrastructure, potentially compromising the integrity and confidentiality of stored cryptographic keys. The flaw enables attackers to manipulate the Keystore's internal data structures through carefully crafted blob inputs, creating a pathway for privilege escalation and unauthorized access to sensitive cryptographic material.
The technical implementation of this vulnerability stems from improper handling of integer values within the Keystore's Blob class during memory allocation and data processing operations. When an application attempts to insert a crafted blob into the Keystore, the system fails to properly validate integer parameters that determine buffer sizes and memory allocations. This integer overflow condition allows attackers to manipulate memory layout and potentially overwrite critical data structures or execute arbitrary code within the Keystore process context. The vulnerability specifically manifests during insert operations where the system processes user-supplied data without adequate bounds checking, creating opportunities for memory corruption that can be exploited by malicious applications.
The operational impact of CVE-2015-3863 extends beyond simple code execution capabilities to encompass complete compromise of the Android cryptographic key storage system. Attackers leveraging this vulnerability can gain access to arbitrary Keystore keys, potentially including encryption keys, digital signatures, and other sensitive cryptographic material. This compromise undermines the fundamental security model of Android's Keystore, which is designed to protect cryptographic keys from unauthorized access and manipulation. The vulnerability's exploitation can result in data theft, identity spoofing, and complete loss of trust in the platform's cryptographic protections, affecting millions of Android devices running vulnerable versions.
Mitigation strategies for this vulnerability require immediate patching of affected Android versions to 5.1.1 LMY48M or later, which includes proper integer overflow protections in the Keystore implementation. Organizations should also implement application sandboxing measures and monitor for suspicious Keystore access patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and maps to ATT&CK technique T1552.001, Credentials in Files, as it enables attackers to extract stored cryptographic credentials. Security professionals should conduct thorough vulnerability assessments of Android applications that interact with Keystore functionality and ensure proper input validation is implemented at all levels of the application stack to prevent similar issues in custom implementations.