CVE-2018-16179 in Direct App
Summary
by MITRE
The Mizuho Direct App for Android version 3.13.0 and earlier does not verify server certificates, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.
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Analysis
by VulDB Data Team • 04/27/2020
The Mizuho Direct App for Android vulnerability CVE-2018-16179 represents a critical security flaw in the mobile banking application's certificate validation mechanism. This vulnerability affects versions 3.13.0 and earlier, where the application fails to properly verify server certificates during secure communications. The absence of certificate verification creates a significant attack surface that enables malicious actors to perform man-in-the-middle attacks against unsuspecting users. The flaw directly violates fundamental security principles of secure communication protocols, as it eliminates the cryptographic verification that ensures users are communicating with legitimate servers rather than attacker-controlled intermediaries.
The technical implementation of this vulnerability stems from improper SSL/TLS certificate validation within the Android application's network security layer. When the Mizuho Direct App establishes connections to its backend servers, it should validate the server certificates against trusted certificate authorities and perform hostname verification to ensure certificate authenticity. However, the application's code fails to execute these critical validation steps, allowing attackers to present fraudulent certificates that the app accepts without question. This weakness specifically aligns with CWE-295, which addresses improper certificate validation, and represents a failure in the application's certificate pinning or validation logic. The vulnerability creates a trust relationship breakdown where the app cannot distinguish between legitimate and malicious server identities, fundamentally undermining the security of all communications between the mobile client and the banking infrastructure.
The operational impact of this vulnerability is severe and multifaceted, particularly within the financial services sector where mobile banking applications handle highly sensitive user data and financial transactions. Attackers exploiting this vulnerability can intercept and manipulate all data transmitted between the mobile device and Mizuho's servers, potentially accessing user account information, transaction details, authentication credentials, and personal identification data. The threat model aligns with ATT&CK technique T1041, which covers data compression and encryption, as attackers can leverage the compromised communication channel to exfiltrate sensitive information. Additionally, the vulnerability enables credential theft through session hijacking, where attackers can capture authentication tokens and use them to impersonate legitimate users. The financial implications extend beyond immediate data theft to include potential fraudulent transactions, identity theft, and reputational damage to both users and the financial institution.
Mitigation strategies for this vulnerability require immediate implementation of proper certificate validation mechanisms within the mobile application. Organizations should implement certificate pinning techniques that explicitly define which certificates or certificate authorities are trusted for the application's communications, preventing the acceptance of fraudulent certificates even if they appear valid. The fix involves updating the application to perform comprehensive certificate validation including chain of trust verification, hostname matching, and expiration date checks. Security patches should be deployed immediately to all affected versions, with users urged to update to the latest application release that includes proper certificate verification. Additionally, network-level monitoring should be implemented to detect anomalous traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of following secure coding practices and implementing proper cryptographic protocols, aligning with NIST SP 800-52 guidelines for certificate management and validation in mobile applications. Regular security assessments and penetration testing should be conducted to ensure that similar certificate validation flaws do not exist in other components of the mobile banking ecosystem.