CVE-2017-9589 in Mobile Banking App
Summary
by MITRE
The "SCSB Shelbyville IL Mobile Banking" by Shelby County State Bank app 3.0.0 -- aka scsb-shelbyville-il-mobile-banking/id938960224 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-2017-9589 affects the Shelby County State Bank mobile banking application version 3.0.0 for iOS devices. This security flaw represents a critical failure in the application's cryptographic implementation where it fails to properly validate X.509 certificates during SSL/TLS connections. The absence of certificate verification creates a significant attack surface that malicious actors can exploit to conduct man-in-the-middle attacks against unsuspecting users. This particular vulnerability resides in the application's secure communication layer, specifically within its SSL/TLS implementation where it should be enforcing certificate validation but instead accepts any certificate presented by the server.
The technical flaw stems from the application's improper handling of SSL certificate validation processes. When establishing secure connections to banking servers, the app should perform certificate chain validation, verify certificate signatures, check certificate expiration dates, and ensure the certificate matches the expected server identity. However, in this case, the application bypasses these essential security checks entirely, allowing attackers to present forged certificates that appear legitimate to the application. This weakness directly violates established security protocols and standards for secure communication, making it susceptible to various attack vectors including certificate spoofing and session hijacking.
The operational impact of this vulnerability is severe and far-reaching for both individual users and the financial institution. Users conducting mobile banking operations through this application become vulnerable to credential theft, financial transaction manipulation, and sensitive data interception. Attackers can exploit this weakness to capture banking credentials, view account balances, initiate unauthorized transfers, and perform other malicious activities without detection. The vulnerability undermines the fundamental security assurances that mobile banking applications are expected to provide, potentially leading to significant financial losses and regulatory compliance issues for the issuing bank. This flaw affects the integrity of the entire mobile banking ecosystem by creating a trusted path that can be easily compromised.
Organizations should implement immediate mitigations including updating the mobile banking application to a version that properly validates SSL certificates, deploying network monitoring tools to detect suspicious certificate behavior, and establishing robust certificate pinning mechanisms. The vulnerability aligns with CWE-295 which specifically addresses "Improper Certificate Validation" and maps to ATT&CK technique T1046 for network service scanning and T1566 for credential harvesting through social engineering. Financial institutions should also consider implementing additional security controls such as mutual authentication, enhanced logging, and regular security assessments to prevent similar vulnerabilities from occurring in other applications. The incident highlights the critical importance of proper cryptographic implementation in financial applications and serves as a reminder of the potential consequences when security measures are inadequately implemented in mobile banking solutions.