CVE-2017-9566 in Mobile Banking App
Summary
by MITRE
The fsb-dequeen-mobile-banking/id1091025340 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.
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Analysis
by VulDB Data Team • 10/18/2019
The vulnerability identified as CVE-2017-9566 affects the fsb-dequeen-mobile-banking iOS application version 3.0.1, representing a critical security flaw in the mobile banking platform's cryptographic implementation. This issue stems from the application's failure to properly validate X.509 certificates during SSL/TLS connections, creating a fundamental weakness in the secure communication channel between the mobile client and backend servers. The flaw directly impacts the certificate validation process, which is essential for establishing trust in secure communications and preventing unauthorized parties from intercepting sensitive financial data.
The technical implementation of this vulnerability demonstrates a classic case of insufficient certificate validation, classified under CWE-295 which specifically addresses improper certificate validation in security protocols. When an application fails to verify X.509 certificates properly, it essentially removes the cryptographic assurance that protects against man-in-the-middle attacks. Attackers can exploit this weakness by presenting fraudulent certificates that appear legitimate to the vulnerable application, allowing them to establish fake secure connections while the mobile banking application believes it is communicating with legitimate servers. This vulnerability operates at the transport layer security level, specifically targeting the SSL/TLS handshake process where certificate verification should occur.
The operational impact of this vulnerability extends beyond simple data interception, as it fundamentally compromises the integrity and confidentiality of mobile banking operations. Financial institutions relying on this application expose their customers to significant risk of credential theft, transaction manipulation, and unauthorized account access. The attack vector enables sophisticated adversaries to perform session hijacking, data exfiltration, and financial fraud operations while remaining undetected by the application's security mechanisms. This vulnerability directly aligns with ATT&CK technique T1046 which describes network service scanning and exploitation of weak cryptographic implementations, and T1566 which covers social engineering attacks that leverage weakened security controls.
Organizations should implement immediate mitigations including updating to patched versions of the mobile banking application, implementing certificate pinning mechanisms, and establishing robust certificate validation policies. The application should be configured to perform strict X.509 certificate validation, including checking certificate chains, validating expiration dates, and verifying certificate signatures against trusted certificate authorities. Security monitoring should be enhanced to detect anomalous certificate behavior and potential man-in-the-middle attacks. Additionally, network-level security controls such as SSL inspection and deep packet inspection should be deployed to identify and block suspicious certificate exchanges. This vulnerability highlights the critical importance of maintaining proper cryptographic security practices in mobile banking applications, as failures in certificate validation can completely undermine the security model of financial applications and expose users to significant financial risk.