CVE-2015-1843 in Docker
Summary
by MITRE
The Red Hat docker package before 1.5.0-28, when using the --add-registry option, falls back to HTTP when the HTTPS connection to the registry fails, which allows man-in-the-middle attackers to conduct downgrade attacks and obtain authentication and image data by leveraging a network position between the client and the registry to block HTTPS traffic. NOTE: this vulnerability exists because of a CVE-2014-5277 regression.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/02/2022
The vulnerability described in CVE-2015-1843 represents a critical security flaw in the Red Hat docker package version 1.5.0-28 and earlier, specifically within the handling of registry connections when the --add-registry option is employed. This issue stems from a regression that was introduced by CVE-2014-5277, creating a dangerous fallback mechanism that undermines the security assurances typically provided by HTTPS encryption. The flaw operates by automatically reverting to unencrypted HTTP connections when HTTPS connectivity to a registry fails, creating an exploitable window where attackers can intercept and manipulate communications between docker clients and registries.
The technical implementation of this vulnerability involves the docker client's connection handling logic that prioritizes HTTPS for secure communications but fails to maintain security posture when HTTPS connections are disrupted. When network interference blocks HTTPS traffic, the client automatically downgrades to HTTP without proper authentication or encryption mechanisms, exposing sensitive data including authentication tokens and image content to potential interception. This behavior creates a man-in-the-middle attack vector that allows adversaries positioned between the client and registry to perform protocol downgrade attacks, essentially forcing the system to use less secure communication channels.
The operational impact of this vulnerability extends beyond simple data interception, as it fundamentally compromises the integrity and confidentiality of container image distribution processes. Attackers can leverage this weakness to gain unauthorized access to private repositories, steal authentication credentials, and potentially modify or inject malicious content into container images during transit. The vulnerability particularly affects organizations that rely on secure registry connections for their containerized applications, as it undermines the security assumptions built into the docker security model. This weakness is especially dangerous in environments where network traffic may be subject to monitoring or manipulation, as the automatic fallback mechanism operates without explicit user awareness or consent.
Mitigation strategies for CVE-2015-1843 focus primarily on upgrading to Red Hat docker package version 1.5.0-28 or later, which resolves the regression issue and maintains proper HTTPS enforcement. Organizations should also implement network-level controls to prevent unauthorized traffic blocking that could trigger the fallback mechanism, including firewall rules and network segmentation strategies. Additional defensive measures include monitoring for unusual connection patterns that might indicate attempted protocol downgrades, implementing certificate pinning for registry connections, and ensuring that all registry communications are properly validated through secure channels. From a compliance standpoint, this vulnerability aligns with CWE-319, which addresses the exposure of sensitive information through improper use of encryption, and maps to ATT&CK technique T1041 for data encryption for exfiltration, highlighting the critical nature of maintaining secure communication channels in containerized environments. The vulnerability demonstrates how seemingly minor implementation details in security protocols can create significant risks when fallback mechanisms are not properly designed to maintain security postures throughout the connection lifecycle.