CVE-2015-9259 in Docker Notary
Summary
by MITRE
In Docker Notary before 0.1, the checkRoot function in gotuf/client/client.go does not check expiry of root.json files, despite a comment stating that it does. Even if a user creates a new root.json file after a key compromise, an attacker can produce update files referring to an old root.json file.
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Analysis
by VulDB Data Team • 01/20/2020
The vulnerability identified as CVE-2015-9259 resides within Docker Notary version 0.1 and earlier, specifically in the checkRoot function located in gotuf/client/client.go. This flaw represents a critical security weakness in the trust management system that governs container image verification and signing within Docker environments. The issue manifests as a failure in proper certificate lifecycle management where the system claims to validate root.json file expiration but fails to actually perform this crucial check. This discrepancy between stated functionality and actual implementation creates a significant attack surface that undermines the integrity of the entire trust ecosystem.
The technical flaw stems from a fundamental disconnect in the code logic where the checkRoot function contains commented assertions about expiration validation but lacks the actual implementation required to enforce these checks. This allows malicious actors to exploit the system by creating new root.json files following a key compromise while simultaneously maintaining access to older, expired root.json files. The vulnerability enables attackers to generate update files that reference compromised historical root.json files, effectively bypassing the intended security controls designed to prevent unauthorized modifications to trusted image repositories.
Operationally, this vulnerability creates a persistent threat vector that can compromise the entire container security infrastructure. Attackers can leverage this weakness to maintain access to compromised systems long after legitimate key revocation should have occurred. The impact extends beyond simple privilege escalation as it undermines the fundamental trust model that container registries rely upon for secure image distribution. This vulnerability directly affects the integrity and authenticity guarantees that Docker Notary is designed to provide, potentially allowing attackers to inject malicious images into trusted repositories without detection.
The security implications align with CWE-295 which addresses improper certificate validation and CWE-310 which covers cryptographic issues related to key management. From an adversarial perspective, this vulnerability maps to multiple ATT&CK techniques including T1552.001 for unsecured credentials and T1078.004 for valid accounts. Organizations using Docker Notary versions prior to 0.1 are particularly vulnerable as the flaw allows attackers to maintain persistent access even after legitimate security events such as key compromises or credential rotations. The recommended mitigation involves upgrading to Docker Notary version 0.1 or later where proper root.json file expiration checking has been implemented, alongside implementing additional monitoring for suspicious root.json file modifications and establishing robust key management practices that include regular rotation and immediate revocation procedures for compromised credentials.