CVE-2017-15582 in Diary with Lock
Summary
by MITRE
In net.MCrypt in the "Diary with lock" (aka WriteDiary) application 4.72 for Android, hardcoded SecretKey and iv variables are used for the AES parameters, which makes it easier for attackers to obtain the cleartext of stored diary entries.
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Analysis
by VulDB Data Team • 12/01/2019
The vulnerability identified as CVE-2017-15582 resides within the net.MCrypt component of the WriteDiary application version 4.72 for Android platforms. This flaw represents a critical cryptographic weakness that directly impacts the security posture of users who rely on the application for storing sensitive personal information. The vulnerability manifests through the improper implementation of encryption algorithms where the application employs hardcoded cryptographic parameters instead of dynamically generated keys and initialization vectors. This design choice fundamentally undermines the security model of the encryption implementation, creating a situation where the cryptographic strength of the system becomes predictable and easily exploitable by malicious actors.
The technical implementation flaw involves the use of fixed SecretKey and iv variables within the AES encryption process, which violates fundamental cryptographic principles and best practices. According to CWE-327, this represents a weakness in the use of a broken cryptographic algorithm where hardcoded values are used instead of secure random generation. The hardcoded nature of these cryptographic parameters means that any attacker who can obtain the application binary or analyze its runtime behavior can extract these fixed values and subsequently decrypt all stored diary entries without requiring additional computational resources or sophisticated attack techniques. This vulnerability directly maps to the ATT&CK technique T1552.004 which involves the use of hardcoded credentials and cryptographic keys.
The operational impact of this vulnerability extends beyond simple data exposure, as it creates a persistent threat vector that remains active throughout the application's lifecycle. Users storing personal, confidential, or sensitive information within the diary application face immediate risk of data compromise, as the encryption mechanism becomes ineffective against determined adversaries. The vulnerability affects all diary entries stored within the application, regardless of when they were created, making it a retrospective security issue that can expose years of stored personal information. Attackers can exploit this weakness through static analysis of the application binary, dynamic analysis during runtime, or through reverse engineering techniques that do not require advanced cryptographic knowledge or specialized tools.
The mitigation strategies for this vulnerability must address both the immediate remediation and long-term security improvements. The primary fix involves implementing proper cryptographic key generation using secure random number generators and ensuring that initialization vectors are properly randomized for each encryption operation. This approach aligns with industry standards such as NIST SP 800-132 and ISO/IEC 19790 which emphasize the importance of using unpredictable and unique cryptographic parameters. Additionally, developers should implement proper key management practices including secure storage of encryption keys, implementation of secure key derivation functions, and consideration of user authentication mechanisms that can provide additional security layers. The application should also incorporate proper error handling and logging mechanisms to detect potential cryptographic attacks or unusual access patterns that might indicate exploitation attempts.