CVE-2017-9571 in Banking App
Summary
by MITRE
The Citizens Community Bank (TN) ccb-mobile-banking/id610030469 app 3.0.1 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.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/18/2019
The vulnerability identified as CVE-2017-9571 affects the Citizens Community Bank mobile banking application version 3.0.1 for iOS devices. This critical security flaw resides in the application's implementation of SSL/TLS certificate verification mechanisms, specifically within the X.509 certificate validation process. The absence of proper certificate verification creates a significant attack vector that compromises the integrity of the secure communication channel between the mobile banking client and the bank's servers. This vulnerability directly impacts the fundamental security principle of authentication, where the application fails to validate the identity of the servers it connects to, leaving users exposed to sophisticated man-in-the-middle attacks.
The technical flaw manifests as a complete failure in X.509 certificate validation within the mobile banking application's secure communication stack. When the application establishes connections to the bank's backend services, it does not perform the necessary verification steps that should confirm the certificate's authenticity, proper issuance by a trusted Certificate Authority, and validity period compliance. This omission allows attackers to present maliciously crafted certificates that appear legitimate to the vulnerable application, effectively bypassing the entire certificate validation process. The vulnerability stems from improper implementation of SSL/TLS security protocols where certificate pinning or validation routines are either completely absent or inadequately implemented, creating a scenario where any attacker with access to a valid certificate authority can impersonate the bank's servers.
The operational impact of this vulnerability is severe and multifaceted, particularly for financial institutions and their customers. Attackers can exploit this weakness to conduct successful man-in-the-middle attacks, intercepting sensitive customer data including account credentials, transaction details, personal identification information, and financial data. The vulnerability undermines the core security model of mobile banking applications, where users trust that their communications are encrypted and authenticated. This flaw enables attackers to not only eavesdrop on communications but also to actively modify transactions, redirect funds, or inject malicious commands into the banking process. The attack surface extends beyond simple data theft to include potential financial fraud, identity theft, and complete compromise of customer banking sessions, making this a critical issue for financial institutions.
This vulnerability maps directly to CWE-295 which specifically addresses "Improper Certificate Validation" and aligns with ATT&CK technique T1041 which covers "Exfiltration Over C2 Channel" and T1566 which addresses "Phishing". The lack of certificate validation creates an environment where attackers can establish unauthorized communication channels with victim applications. Mitigation strategies should include immediate implementation of proper certificate validation mechanisms, including certificate pinning where appropriate, and ensuring all SSL/TLS connections perform comprehensive X.509 certificate verification. Organizations should also consider implementing additional security controls such as runtime application self-protection, network monitoring for anomalous communication patterns, and regular security assessments of mobile applications. The fix requires complete reimplementation of the SSL/TLS certificate validation logic to ensure proper certificate chain validation, expiration checking, and trust anchor verification, while also considering industry best practices for mobile application security as outlined in standards such as NIST SP 800-53 and ISO/IEC 27001.