CVE-2017-5916 in Mobile Banking
Summary
by MITRE
The America's First Federal Credit Union (FCU) Mobile Banking app 3.1.0 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 • 09/24/2020
The vulnerability identified as CVE-2017-5916 represents a critical security flaw in the America's First Federal Credit Union Mobile Banking application version 3.1.0 for iOS devices. This weakness stems from the application's failure to properly validate X.509 certificates during SSL/TLS communications, creating a significant attack surface that adversaries can exploit to compromise user data and financial transactions. The flaw directly impacts the integrity of the secure communication channel between the mobile banking client and the credit union's backend servers, undermining the fundamental security assurances that users expect from financial applications.
The technical nature of this vulnerability aligns with CWE-295, which specifically addresses improper certificate validation in secure communications. The mobile banking application's inability to verify SSL server certificates creates a man-in-the-middle attack vector where malicious actors can intercept and manipulate communications between the user's device and the legitimate banking servers. This occurs because the application accepts any certificate presented by the server without performing proper validation checks against trusted certificate authorities or implementing certificate pinning mechanisms. Attackers can generate and present crafted certificates that appear legitimate to the vulnerable application, enabling them to establish fake secure connections and capture sensitive information transmitted through the compromised channel.
The operational impact of this vulnerability extends beyond simple data interception, as it fundamentally undermines the trust model that mobile banking applications rely upon for user protection. Financial institutions and their customers depend on the SSL/TLS protocol to ensure confidentiality and integrity of transactions, authentication of servers, and protection against eavesdropping. When certificate verification is bypassed, attackers can not only steal login credentials, account numbers, and transaction details but also manipulate banking operations in real-time. This vulnerability creates an environment where attackers can perform session hijacking, conduct fraudulent transfers, and execute unauthorized financial transactions while remaining undetected by the application's security mechanisms.
The implications of this vulnerability align with several tactics 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 employ similar credentials across different platforms. The vulnerability also enables defense evasion techniques as the malicious activity occurs within what appears to be legitimate secure communications, making detection more challenging for network monitoring systems. Additionally, the compromised application creates opportunities for lateral movement within the financial ecosystem, as stolen credentials could be used to access other systems or services that may share similar authentication mechanisms.
Organizations should implement immediate mitigations including certificate pinning for all mobile banking applications, enforcement of strict certificate validation policies, and regular security audits of mobile applications. The application architecture should be redesigned to include proper certificate chain validation, implementation of certificate transparency checks, and integration with trusted certificate authority verification services. Security teams must also establish monitoring protocols to detect anomalous certificate behavior and implement automated testing procedures to validate certificate handling mechanisms. The vulnerability underscores the critical importance of mobile application security in financial services, where the failure of basic security controls can result in catastrophic financial and reputational damage.