CVE-2017-15997 in NQ Contacts Backup
Summary
by MITRE
In the "NQ Contacts Backup & Restore" application 1.1 for Android, RC4 encryption is used to secure the user password locally stored in shared preferences. Because there is a static RC4 key, an attacker can gain access to user credentials more easily by leveraging access to the preferences XML file.
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Analysis
by VulDB Data Team • 12/02/2019
The vulnerability described in CVE-2017-15997 represents a critical cryptographic weakness in the NQ Contacts Backup & Restore Android application version 1.1. This flaw demonstrates poor security implementation practices where the developers chose to implement RC4 encryption for protecting user credentials stored locally on the device. The vulnerability stems from the use of a static encryption key within the application code, which fundamentally undermines the security of the encryption mechanism. The application stores user passwords in shared preferences using RC4 encryption with a hardcoded key, creating a scenario where any attacker with access to the device can easily extract and decrypt the stored credentials. This represents a direct violation of security best practices and exposes sensitive user data to unauthorized access.
The technical implementation of this vulnerability involves the application's reliance on RC4 encryption algorithm with a static key embedded within the application binary. RC4, while once widely used, has been deprecated due to numerous cryptographic weaknesses including key scheduling vulnerabilities and bias in the output stream. The static nature of the encryption key means that the same key is used across all instances of the application, eliminating any cryptographic entropy that might otherwise provide security. When an attacker gains access to the shared preferences XML file, they can directly extract the encrypted password data and use the static key to decrypt it without requiring additional computational resources or complex cryptographic attacks. This vulnerability falls under CWE-327, which specifically addresses the use of weak cryptographic algorithms and improper key management practices.
The operational impact of this vulnerability extends beyond simple credential theft, as it provides attackers with persistent access to user contact data that may contain sensitive personal information, business contacts, or other confidential data. The attack vector is particularly concerning because it requires minimal privileges to exploit - an attacker only needs access to the application's shared preferences file, which is typically accessible to any user with local device access. This weakness creates a persistent threat where compromised devices can be used to access backup data from multiple users, especially in enterprise environments where such applications might be deployed. The vulnerability also aligns with ATT&CK technique T1213.002, which covers data from local system, demonstrating how attackers can leverage local application data to gain unauthorized access to user information.
Mitigation strategies for this vulnerability require immediate remediation of the cryptographic implementation within the application. The most effective solution involves replacing the static RC4 encryption with a modern, secure encryption algorithm such as AES-256 with properly generated and managed keys. The application should implement proper key derivation functions like PBKDF2 or scrypt to generate encryption keys from user passwords rather than using hardcoded static keys. Additionally, the application should consider implementing proper access controls and encryption key management practices that align with industry standards such as NIST SP 800-38A for block cipher modes of operation. The shared preferences should also be secured with proper file permissions and encryption at rest to prevent unauthorized access to the preference files themselves. Organizations should also implement regular security audits and code reviews to identify similar cryptographic weaknesses in other applications and ensure compliance with established security frameworks and standards.