CVE-2017-5918 in BCR Movil
Summary
by MITRE
The Banco de Costa Rica BCR Movil app 3.7 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-2017-5918 represents a critical security flaw in the Banco de Costa Rica BCR Movil mobile application version 3.7 for iOS devices. This weakness stems from the application's failure to properly validate X.509 certificates during SSL/TLS communications, creating a significant pathway for malicious actors to execute man-in-the-middle attacks against unsuspecting users. The vulnerability specifically affects the mobile banking application's cryptographic security implementation, which is fundamental to protecting financial transactions and user data integrity.
The technical flaw manifests in the application's inability to perform proper certificate chain validation and trust verification processes. When the BCR Movil app establishes secure connections to banking servers, it fails to validate the server certificates against trusted certificate authorities or check for proper certificate signatures and expiration dates. This omission allows attackers to present fraudulent certificates that appear legitimate to the application, enabling them to intercept and manipulate encrypted communications between users and the bank's servers. The vulnerability falls under CWE-295 which specifically addresses improper certificate validation in security protocols.
The operational impact of this vulnerability extends far beyond simple data interception, as it fundamentally undermines the security model of mobile banking transactions. Attackers exploiting this weakness can impersonate legitimate banking servers and capture sensitive user information including login credentials, account numbers, transaction details, and personal identification data. The implications are particularly severe for financial institutions as this vulnerability could enable complete account takeover scenarios, unauthorized fund transfers, and comprehensive data breaches that compromise user financial security and institutional reputation. The attack vector aligns with ATT&CK technique T1041 which describes data compression and encryption for exfiltration, as malicious actors could leverage this vulnerability to capture and exfiltrate banking data.
Mitigation strategies for this vulnerability require immediate implementation of proper certificate validation mechanisms within the mobile application. Organizations should implement certificate pinning techniques to ensure that only pre-approved certificates from trusted authorities are accepted, thereby preventing attackers from using fraudulent certificates. Additionally, the application must be updated to perform comprehensive X.509 certificate validation including checking certificate authority signatures, expiration dates, and certificate chain integrity. Security patches should also include proper error handling for certificate validation failures, ensuring that any certificate verification issues result in immediate connection termination rather than proceeding with potentially compromised communications. The remediation efforts should follow industry best practices outlined in NIST SP 800-52 for certificate management and TLS implementation guidelines.