CVE-2015-6303 in Spark Browser
Summary
by MITRE
The Cisco Spark application 2015-07-04 for mobile operating systems does not properly 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, aka Bug IDs CSCut36742 and CSCut36844.
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Analysis
by VulDB Data Team • 12/30/2017
The vulnerability identified as CVE-2015-6303 affects the Cisco Spark mobile application released on 2015-07-04, representing a critical security flaw in the application's SSL/TLS certificate validation mechanism. This weakness stems from improper X.509 certificate verification processes that fail to adequately authenticate server identities during secure communications. The vulnerability creates a significant attack surface that enables malicious actors to perform man-in-the-middle attacks by presenting fraudulent certificates that appear legitimate to the vulnerable application. The specific bug identifiers CSCut36742 and CSCut36844 highlight the targeted nature of this certificate validation failure within the application's cryptographic implementation.
The technical flaw manifests in the application's failure to properly validate certificate chains and verify the authenticity of SSL/TLS certificates presented by servers. This inadequate certificate verification process allows attackers to generate or obtain certificates that can bypass the application's security checks, enabling them to impersonate legitimate servers. The vulnerability specifically impacts mobile operating systems where the Cisco Spark application is deployed, making it particularly concerning given the widespread use of mobile devices for business communications. Attackers can exploit this weakness by presenting crafted certificates that contain valid signatures but are not properly verified against trusted certificate authorities, thereby deceiving the application into establishing secure connections with malicious servers.
The operational impact of this vulnerability extends beyond simple data interception, as it provides attackers with the capability to obtain sensitive information transmitted through the compromised application. This includes but is not limited to user credentials, confidential business communications, personal information, and potentially corporate data. The vulnerability undermines the fundamental security assurances that SSL/TLS protocols are designed to provide, effectively rendering the application's encrypted communications vulnerable to unauthorized access. Organizations relying on Cisco Spark for business communications face significant risk of data breaches and information disclosure, particularly in environments where sensitive corporate data is regularly exchanged.
The security implications of CVE-2015-6303 align with CWE-295, which addresses "Improper Certificate Validation" in security protocols, and maps to ATT&CK technique T1041, which covers "Exfiltration Over C2 Channel" through compromised communication channels. Organizations should implement immediate mitigations including updating to patched versions of the Cisco Spark application, implementing network-level monitoring for suspicious certificate behavior, and establishing robust certificate pinning mechanisms where possible. The vulnerability also highlights the importance of proper certificate validation practices as outlined in industry standards such as RFC 5280 for X.509 certificate specifications and NIST SP 800-57 for cryptographic key management. Network administrators should consider implementing certificate transparency monitoring and regular security assessments to detect potential exploitation attempts. Given the mobile nature of the affected application, organizations must also ensure that their mobile device management policies include provisions for timely security updates and that users are educated about the risks associated with using vulnerable applications in sensitive environments.