CVE-2018-15382 in HyperFlex System
Summary
by MITRE
A vulnerability in Cisco HyperFlex Software could allow an unauthenticated, remote attacker to generate valid, signed session tokens. The vulnerability is due to a static signing key that is present in all Cisco HyperFlex systems. An attacker could exploit this vulnerability by accessing the static signing key from one HyperFlex system and using it to generate valid, signed session tokens for another HyperFlex system. A successful exploit could allow the attacker to access the HyperFlex Web UI of a system for which they are not authorized.
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Analysis
by VulDB Data Team • 03/30/2020
The vulnerability identified as CVE-2018-15382 represents a critical authentication bypass flaw in Cisco HyperFlex Software that fundamentally undermines the security posture of affected systems. This weakness stems from the improper implementation of session token generation mechanisms where a static cryptographic signing key is embedded within all instances of the HyperFlex software. The flaw exists at the core of the authentication system, creating a scenario where any attacker with access to this static key can forge legitimate session tokens for arbitrary systems within the HyperFlex environment. This vulnerability falls under CWE-326, which specifically addresses inadequate encryption strength, and more broadly relates to CWE-310, concerning cryptographic vulnerabilities. The security implications extend beyond simple unauthorized access, as the flaw enables attackers to perform operations within the HyperFlex Web UI that should only be accessible to legitimate administrators.
The technical exploitation of this vulnerability requires minimal prerequisites since the static signing key is already present within each HyperFlex system. Attackers can simply extract this key from one system and utilize it to generate valid session tokens for other systems within the same network infrastructure. This cross-system token generation capability creates a particularly dangerous scenario where a single compromised system can serve as a launching point for attacks against multiple HyperFlex deployments. The flaw demonstrates a fundamental misunderstanding of cryptographic key management principles, where a static key should never be embedded in software that is distributed across multiple systems. The vulnerability aligns with ATT&CK technique T1550.001, which covers use of valid accounts, but operates at a lower level by enabling the creation of valid tokens without requiring legitimate credentials. The static nature of the key means that once discovered, it can be used indefinitely against any system running the vulnerable software version.
The operational impact of this vulnerability extends far beyond simple unauthorized access to the web interface. An attacker with successfully generated valid session tokens could potentially perform administrative functions, modify system configurations, access sensitive data, and compromise the integrity of the entire HyperFlex environment. The attack surface is particularly concerning given that HyperFlex systems are often deployed in enterprise environments where they manage critical storage and compute resources. The vulnerability affects the availability and confidentiality of data stored within the HyperFlex infrastructure, as unauthorized access could lead to data exfiltration or system disruption. Organizations may face significant compliance implications, as this vulnerability could violate various regulatory requirements for data protection and access control. The flaw also creates a persistent threat vector since the static key remains in place across all affected systems, meaning that organizations cannot simply patch or update their systems to resolve the issue without replacing the entire software stack.
Mitigation strategies for this vulnerability require immediate action from affected organizations to address the root cause of the static key implementation. Cisco has issued patches and updates to resolve this issue, but organizations should also implement network segmentation to limit access to HyperFlex systems and monitor for unauthorized token generation activities. The implementation of additional authentication layers such as multi-factor authentication should be considered as a compensating control, though the fundamental flaw in the token generation mechanism must be addressed through software updates. Organizations should also conduct thorough inventory assessments to identify all affected HyperFlex deployments and ensure that patches are applied consistently across all systems. The vulnerability highlights the importance of proper key management practices and the dangers of embedding cryptographic keys within software that is distributed across multiple environments, serving as a reminder of the principles outlined in NIST SP 800-57 for cryptographic key management. Regular security assessments and penetration testing should be performed to identify similar implementation flaws in other enterprise systems that may be vulnerable to similar attacks.