CVE-2017-9595 in Mobile Banking App
Summary
by MITRE
The "First State Bank of Bigfork Mobile Banking" by First State Bank of Bigfork app 4.0.3 -- aka first-state-bank-of-bigfork-mobile-banking/id1133969876 for iOS does not verify X.509 certificates from SSL servers, 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 • 10/18/2019
The vulnerability identified as CVE-2017-9595 affects the First State Bank of Bigfork mobile banking application version 4.0.3 for iOS devices. This represents a critical security flaw in the application's secure communication implementation that directly impacts the integrity of data transmission between the mobile client and backend servers. The issue stems from the application's failure to properly validate SSL/TLS certificates during the secure connection establishment process, creating a significant attack surface that malicious actors can exploit to compromise user data and financial transactions.
The technical flaw manifests as a complete absence of X.509 certificate verification within the application's SSL/TLS implementation. This means that when the mobile banking app establishes a secure connection to the bank's servers, it does not validate the server's certificate against trusted certificate authorities or perform any cryptographic verification of the certificate's authenticity. The vulnerability aligns with CWE-295, which specifically addresses improper certificate validation in security protocols, and represents a fundamental breakdown in the application's trust model that undermines the entire purpose of SSL/TLS encryption. This weakness allows attackers to perform man-in-the-middle attacks by presenting fraudulent certificates that the application will accept without question, effectively breaking the cryptographic protection that should safeguard sensitive financial data transmission.
The operational impact of this vulnerability is severe and multifaceted, particularly within the financial services sector where mobile banking applications handle highly sensitive user information including account credentials, transaction details, and personal identification data. Attackers can exploit this weakness to intercept and modify communications between users and the banking servers, potentially gaining access to user login credentials, account balances, transaction histories, and other confidential financial information. The vulnerability creates an environment where malicious actors can impersonate legitimate banking servers, redirect users to fraudulent websites, or simply eavesdrop on sensitive transactions without detection. This type of attack vector directly violates industry standards and best practices established by organizations such as the National Institute of Standards and Technology and the Financial Services Information Sharing and Analysis Center, which mandate proper certificate validation as a fundamental security control for financial applications.
The implications extend beyond immediate data theft to include potential financial fraud, identity theft, and reputational damage for both the bank and its customers. Given that this vulnerability affects a mobile banking application, the attack surface is particularly broad as users may access their accounts from various locations and networks, increasing the likelihood of successful exploitation. The lack of certificate verification creates a persistent risk that remains active as long as the vulnerable application version is in use, making it an attractive target for cybercriminals who can leverage this weakness across multiple user sessions and transactions. Organizations should consider this vulnerability in the context of ATT&CK framework's T1046 and T1566 techniques, which address network service scanning and credential access through man-in-the-middle attacks, further emphasizing the critical need for immediate remediation and implementation of proper SSL/TLS certificate validation mechanisms.
Mitigation strategies for this vulnerability require immediate implementation of proper X.509 certificate validation procedures within the mobile application's SSL/TLS stack. The application must be updated to perform comprehensive certificate chain validation, including checking certificate expiration dates, verifying certificate signatures against trusted root authorities, and ensuring proper hostname verification. Security patches should implement certificate pinning mechanisms where appropriate, and the application should be configured to reject connections to servers presenting untrusted or self-signed certificates. Regular security audits and penetration testing should be conducted to ensure that certificate validation mechanisms remain effective against evolving attack techniques. Additionally, the bank should implement monitoring systems to detect anomalous network traffic patterns that might indicate exploitation attempts, and users should be educated about the importance of only downloading applications from official app stores and maintaining up-to-date mobile device operating systems to minimize potential attack vectors.