CVE-2015-7298 in Desktop Client
Summary
by MITRE
ownCloud Desktop Client before 2.0.1, when compiled with a Qt release after 5.3.x, does not call QNetworkReply::ignoreSslErrors with the list of errors to be ignored, which makes it easier for remote attackers to conduct man-in-the-middle (MITM) attacks by leveraging a server using a self-signed certificate. NOTE: this vulnerability exists because of a partial CVE-2015-4456 regression.
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Analysis
by VulDB Data Team • 05/11/2018
The vulnerability described in CVE-2015-7298 represents a critical security flaw in the ownCloud Desktop Client version 2.0.0 and earlier, specifically when compiled with Qt versions released after 5.3.x. This issue fundamentally undermines the client's ability to properly validate SSL certificates during network communications, creating a significant attack surface for malicious actors. The problem stems from a regression in the Qt networking stack that was initially addressed in CVE-2015-4456, but was subsequently reintroduced or inadequately fixed in the ownCloud client implementation. The vulnerability operates at the transport layer security level, where proper certificate validation mechanisms fail to execute correctly, leaving users exposed to various forms of network-based attacks.
The technical root cause of this vulnerability lies in the improper handling of SSL certificate validation within the Qt networking framework. When the ownCloud client connects to a server using SSL/TLS, it should explicitly call QNetworkReply::ignoreSslErrors with a specific list of SSL errors that are acceptable to ignore. However, in affected versions, this call is made without specifying the error types, which effectively disables proper SSL certificate validation. This behavior creates a dangerous scenario where the client will accept any SSL certificate, including self-signed certificates that are commonly used in internal networks or by attackers. The flaw is particularly insidious because it allows attackers to present forged certificates that appear legitimate to the client, enabling them to intercept and potentially modify data in transit. This regression essentially removes the security guarantees that SSL/TLS is designed to provide, making the client susceptible to man-in-the-middle attacks where attackers can position themselves between the client and server to eavesdrop on communications or inject malicious content.
The operational impact of this vulnerability extends beyond simple data interception, as it fundamentally compromises the integrity and confidentiality of all data transmitted between the ownCloud client and the server. Attackers can exploit this weakness to perform various malicious activities including credential theft, data exfiltration, and content manipulation without detection. The vulnerability is particularly dangerous in enterprise environments where internal servers might use self-signed certificates for legitimate reasons, but attackers can exploit the client's weak validation to impersonate these servers. From an attack perspective, this vulnerability aligns with the MITRE ATT&CK framework's technique T1041 for data compression and T1566 for credential access through network sniffing, as it enables attackers to capture and potentially modify network traffic. The issue also relates to CWE-295, which specifically addresses improper certificate validation, and CWE-310, which deals with cryptographic issues in SSL/TLS implementations.
Mitigation strategies for this vulnerability require immediate action from users and administrators to upgrade to the patched version 2.0.1 or later of the ownCloud Desktop Client. The upgrade process should be prioritized as it directly addresses the core SSL validation flaw that renders the client vulnerable to man-in-the-middle attacks. Additionally, organizations should implement network monitoring solutions to detect unusual certificate behavior or unexpected network traffic patterns that might indicate exploitation attempts. Security teams should also review their certificate management policies to ensure that self-signed certificates are properly managed and that users are not inadvertently trusting unverified certificates. The fix implemented in version 2.0.1 properly addresses the Qt networking regression by ensuring that QNetworkReply::ignoreSslErrors is called with appropriate error specifications, thereby restoring proper SSL certificate validation. This remediation aligns with industry best practices for secure coding and demonstrates the importance of maintaining proper SSL/TLS certificate validation in client applications, particularly those handling sensitive data in cloud environments. Organizations should also consider implementing additional security controls such as network segmentation and secure certificate deployment practices to further reduce the attack surface and protect against similar vulnerabilities in other applications.