CVE-2017-9596 in Mobile Banking App
Summary
by MITRE
The "CFB Mobile Banking" by Citizens First Bank Wisconsin app 3.0.1 -- aka cfb-mobile-banking/id1081102805 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 CVE-2017-9596 vulnerability affects the CFB Mobile Banking application version 3.0.1 for iOS devices, representing a critical security flaw in the mobile banking ecosystem. This vulnerability stems from the application's failure to properly validate X.509 certificates during SSL/TLS connections, creating a significant weakness in the cryptographic security framework that protects financial transactions. The flaw specifically impacts the certificate verification process, which is fundamental to establishing trust between mobile banking clients and secure financial servers. Mobile banking applications must implement robust certificate validation to prevent attackers from exploiting the trust model that underpins secure communications.
The technical implementation of this vulnerability involves the application's SSL/TLS stack failing to perform proper certificate chain validation and hostname checking. This allows attackers to present fraudulent certificates that appear legitimate to the application, enabling them to intercept and manipulate sensitive financial data transmitted between the mobile device and the bank's servers. The vulnerability creates a path for man-in-the-middle attacks where adversaries can position themselves between the mobile application and legitimate servers, decrypting and potentially modifying financial transactions in transit. This weakness directly violates the core principles of secure communication protocols and demonstrates a failure in the application's security architecture.
The operational impact of this vulnerability extends beyond simple data theft, encompassing the complete compromise of mobile banking security. Attackers could potentially access account balances, transaction histories, and personal financial information, while also enabling more sophisticated attacks such as transaction manipulation or unauthorized fund transfers. The vulnerability affects all users of the specific iOS application version, creating a widespread risk across the mobile banking user base for Citizens First Bank Wisconsin. This type of flaw represents a significant breach in the security model that financial institutions rely upon to protect customer data, potentially leading to regulatory violations and substantial financial losses.
Organizations should implement immediate mitigations including updating the mobile application to a version that properly validates SSL certificates, implementing additional network-level security controls such as certificate pinning, and conducting comprehensive security assessments of mobile banking applications. The vulnerability aligns with CWE-295, which addresses improper certificate validation, and represents a clear violation of security best practices outlined in NIST SP 800-52 for certificate management. From an ATT&CK framework perspective, this vulnerability maps to T1046 Network Service Scanning and T1566 Phishing, as attackers can leverage the compromised application to conduct network reconnaissance and financial phishing attacks. Organizations must also consider implementing additional security controls such as network monitoring for unusual SSL traffic patterns and regular security testing of mobile applications to prevent similar vulnerabilities from being introduced in future releases.