CVE-2015-8234 in Glance
Summary
by MITRE
The image signature algorithm in OpenStack Glance 11.0.0 allows remote attackers to bypass the signature verification process via a crafted image, which triggers an MD5 collision.
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Analysis
by VulDB Data Team • 08/23/2020
The vulnerability identified as CVE-2015-8234 resides within the image signature algorithm implementation of OpenStack Glance version 11.0.0, representing a critical security flaw that undermines the integrity verification mechanisms designed to protect cloud image repositories. This weakness specifically targets the cryptographic validation process that ensures images have not been tampered with during storage or transmission within OpenStack environments. The flaw enables malicious actors to craft specially designed images that can bypass the signature verification checks, effectively allowing unauthorized modifications to remain undetected within the cloud infrastructure.
The technical root cause of this vulnerability stems from the implementation's reliance on MD5 hashing algorithms for image signature verification, which has been widely deprecated due to known cryptographic weaknesses and collision vulnerabilities. When attackers construct images that exploit MD5 collision properties, they can create two distinct image files that produce identical MD5 hash values, thereby fooling the verification system into accepting maliciously modified content as authentic. This vulnerability aligns with CWE-327, which specifically addresses the use of weak cryptographic algorithms and the exploitation of known hash collision vulnerabilities. The flaw demonstrates a fundamental failure in cryptographic implementation security practices where legacy hashing mechanisms were retained despite being vulnerable to sophisticated attack vectors.
The operational impact of CVE-2015-8234 extends far beyond simple integrity validation failures, as it fundamentally compromises the trust model of OpenStack Glance image repositories and potentially affects the entire cloud infrastructure that relies on these images for deployment. Attackers can leverage this vulnerability to inject malicious code into images that would otherwise be rejected by the signature verification system, potentially leading to privilege escalation, data exfiltration, or complete system compromise. The implications are particularly severe in multi-tenant cloud environments where image integrity is crucial for maintaining isolation between different users and workloads, as demonstrated by ATT&CK technique T1553.002 which covers code signing policy manipulation and T1059.001 for execution through malicious image content. Organizations using OpenStack Glance 11.0.0 are vulnerable to persistent threats that can remain undetected for extended periods while maintaining access to cloud resources.
Mitigation strategies for CVE-2015-8234 require immediate implementation of cryptographic algorithm upgrades and comprehensive system hardening measures to address the underlying MD5 collision vulnerability. Organizations should prioritize upgrading to OpenStack Glance versions that utilize stronger cryptographic hashing algorithms such as SHA-256 or SHA-3, which are resistant to collision attacks and provide adequate security for image verification processes. The remediation approach must include thorough vulnerability assessment of existing image repositories to identify and replace any compromised images, along with implementing additional verification layers such as digital signatures using RSA or ECDSA algorithms that are resistant to the types of attacks that exploit MD5 weaknesses. Security teams should also establish monitoring procedures to detect unauthorized image modifications and implement proper access controls to limit who can upload or modify images within the Glance service, as outlined in the NIST SP 800-53 security controls for integrity verification and access control mechanisms.