CVE-2017-3213 in Mobile Banking
Summary
by MITRE
The Think Mutual Bank Mobile Banking app 3.1.5 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 • 09/23/2020
The vulnerability identified as CVE-2017-3213 affects the Think Mutual Bank Mobile Banking application version 3.1.5 for iOS devices, representing a critical security flaw in the application's SSL/TLS certificate validation mechanism. This issue falls under the category of improper certificate validation, which is classified as CWE-295 within the Common Weakness Enumeration framework. The vulnerability specifically targets the mobile banking application's failure to properly implement X.509 certificate verification during secure communications with backend servers, creating a significant attack surface that adversaries can exploit to compromise user data and financial transactions.
The technical flaw manifests when the mobile banking application establishes SSL connections to remote servers without performing proper certificate chain validation. This omission allows attackers to perform man-in-the-middle attacks by presenting forged SSL certificates that appear legitimate to the vulnerable application. The certificate validation process should normally verify the certificate's authenticity through trusted certificate authorities, check certificate expiration dates, and validate the certificate chain back to a trusted root certificate. However, the Think Mutual Bank application bypasses these essential security checks, enabling attackers to intercept and manipulate communications between users and the bank's servers.
The operational impact of this vulnerability extends beyond simple data interception, as it fundamentally undermines the security model of mobile banking applications. Attackers can exploit this weakness to redirect users to malicious servers, capture login credentials, access account information, and potentially execute unauthorized financial transactions. The vulnerability is particularly dangerous because it affects a mobile banking application where users expect robust security measures to protect their financial data. The lack of certificate verification means that even if users believe they are connecting to their bank's legitimate servers, they may actually be communicating with attacker-controlled systems that can capture all transmitted information.
This vulnerability directly maps to several techniques described in the MITRE ATT&CK framework, particularly those related to credential access and defense evasion. Attackers can leverage this weakness to perform credential harvesting through man-in-the-middle attacks, potentially gaining access to multiple accounts if users reuse passwords across different services. The attack vector is particularly effective in public Wi-Fi environments where network traffic interception is common, making the vulnerability exploitable in real-world scenarios without requiring physical access to the target device. Organizations should consider implementing additional security controls such as certificate pinning, which would prevent the application from accepting any certificates except those explicitly trusted, regardless of the certificate chain validation results.
The remediation approach for this vulnerability requires immediate implementation of proper SSL certificate validation mechanisms within the mobile banking application. This includes enforcing certificate chain validation, implementing certificate pinning for critical endpoints, and ensuring that all certificate verification processes follow industry standards such as those defined in RFC 5280 for X.509 certificates. Additionally, the application should be updated to validate certificate expiration dates, check certificate revocation status through OCSP or CRL checks, and maintain an up-to-date trust store with only legitimate certificate authorities. Organizations should also consider implementing network-level security controls such as secure DNS resolution and traffic inspection to provide additional layers of protection against man-in-the-middle attacks. The vulnerability underscores the critical importance of proper cryptographic implementation in mobile financial applications and highlights the need for comprehensive security testing including penetration testing and code review processes to identify similar weaknesses in other mobile applications.