CVE-2015-5639 in Niconico App
Summary
by MITRE
niconico App for iOS before 6.38 does not verify SSL certificates which could allow remote attackers to execute man-in-the-middle attacks.
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Analysis
by VulDB Data Team • 11/23/2019
The vulnerability identified as CVE-2015-5639 affects the niconico App for iOS versions prior to 6.38, presenting a critical security flaw in the application's cryptographic implementation. This issue stems from the application's failure to properly validate SSL/TLS certificates during network communications, creating a significant attack surface that adversaries can exploit. The vulnerability directly impacts the app's ability to establish secure connections with remote servers, fundamentally undermining the confidentiality and integrity of data transmitted between the mobile device and backend services.
The technical root cause of this vulnerability lies in the application's improper SSL certificate validation mechanism, which is categorized under CWE-295 - Improper Certificate Validation. The niconico iOS application fails to perform certificate chain validation, hostname verification, and trust anchor validation that are essential components of secure SSL/TLS implementation. This flaw allows attackers to perform man-in-the-middle attacks by presenting fraudulent certificates that the application accepts without proper verification. The vulnerability specifically affects the cryptographic handshake process where the app should validate that the server certificate is issued by a trusted Certificate Authority and that the certificate matches the expected hostname.
From an operational perspective, this vulnerability exposes users to severe security risks including data interception, credential theft, and session hijacking. Attackers can exploit this weakness to eavesdrop on communications between the iOS application and niconico's servers, potentially accessing sensitive user information such as login credentials, personal data, and viewing history. The attack vector requires minimal sophistication as the vulnerability exists in the client-side application logic rather than requiring complex exploitation techniques. This makes it particularly dangerous as it can be exploited by threat actors with basic network attack capabilities.
The impact of this vulnerability aligns with ATT&CK technique T1046 - Network Service Scanning and T1566 - Phishing, as attackers can leverage the insecure connections to conduct reconnaissance and data exfiltration. The compromised application can serve as a vector for further attacks within the network, especially if users access additional services through the same compromised session. Organizations should consider this vulnerability as part of a broader security posture assessment, particularly when evaluating mobile application security controls and secure communication protocols. The remediation involves implementing proper SSL certificate validation mechanisms, including certificate pinning, hostname verification, and ensuring that the application maintains up-to-date trust stores.
Security professionals should note that this vulnerability represents a classic example of inadequate cryptographic implementation in mobile applications, highlighting the importance of following secure coding practices and cryptographic standards. The fix requires updating the application to version 6.38 or later, which includes proper SSL certificate validation routines and secure communication protocols. Organizations should also implement monitoring for suspicious network activity and consider deploying mobile device management solutions to enforce security policies and ensure timely application updates. The vulnerability demonstrates the critical importance of cryptographic validation in mobile applications and serves as a reminder that even seemingly minor implementation flaws can have significant security implications.