CVE-2023-2197 in Vault Enterprise
Summary
by MITRE • 05/01/2023
HashiCorp Vault Enterprise 1.13.0 up to 1.13.1 is vulnerable to a padding oracle attack when using an HSM in conjunction with the CKM_AES_CBC_PAD or CKM_AES_CBC encryption mechanisms. An attacker with privileges to modify storage and restart Vault may be able to intercept or modify cipher text in order to derive Vault’s root key. Fixed in 1.13.2
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Analysis
by VulDB Data Team • 01/30/2025
HashiCorp Vault Enterprise versions 1.13.0 through 1.13.1 contain a critical padding oracle vulnerability that specifically affects deployments utilizing Hardware Security Modules for encryption operations. This vulnerability manifests when Vault employs the CKM_AES_CBC_PAD or CKM_AES_CBC encryption mechanisms in conjunction with HSMs, creating a scenario where an attacker can exploit the padding validation process to gain access to the root key. The flaw stems from improper handling of padding validation responses during decryption operations, which inadvertently reveals information about the validity of padding bytes to an attacker. This vulnerability operates under the broader category of cryptographic side-channel attacks and aligns with CWE-203, which addresses the exposure of sensitive information through side channels.
The technical exploitation of this vulnerability requires an attacker to possess privileges that allow modification of Vault's storage layer and the ability to restart the Vault service. This combination of privileges enables the attacker to perform a series of carefully crafted encryption and decryption operations that can be used to iteratively determine the root key through padding oracle attacks. The vulnerability specifically targets the CBC (Cipher Block Chaining) mode of operation where padding validation errors are handled in a way that provides distinguishable responses to the attacker. When an attacker can observe whether padding validation succeeds or fails, they can use this information to reconstruct the plaintext and ultimately derive the root key. This attack pattern is consistent with the ATT&CK framework's T1552.001 technique for "Unsecured Credentials" and T1005 for "Data from Local System."
The operational impact of this vulnerability extends beyond simple privilege escalation as it fundamentally compromises the core security model of Vault Enterprise. Successful exploitation can lead to complete compromise of the secrets management system, allowing attackers to access all stored secrets, certificates, and sensitive data that Vault protects. The vulnerability is particularly dangerous because it can be exploited even when Vault's HSM is properly configured, as the issue lies in how Vault handles the padding validation rather than in the HSM itself. Organizations using Vault with HSMs for encryption should immediately assess their exposure to this vulnerability, as the attack requires minimal privileges compared to other exploitation methods. The fix in version 1.13.2 addresses the padding oracle issue by implementing proper error handling that does not reveal padding validation information to attackers. This remediation aligns with industry best practices for cryptographic implementations and represents a critical security update that should be prioritized across all affected deployments.
The vulnerability demonstrates the importance of proper cryptographic implementation practices and highlights the risks associated with complex security systems that combine multiple security layers. Organizations should ensure that all cryptographic operations in their security infrastructure are properly validated against known attack patterns and that error handling does not inadvertently provide information that could be exploited by attackers. This particular vulnerability underscores the need for regular security assessments and the importance of staying current with security patches for enterprise security tools. The attack vector emphasizes the principle of least privilege, as the vulnerability requires specific storage modification and restart privileges that should be carefully controlled. Security teams should implement monitoring for suspicious storage modification activities and ensure that restart operations are properly audited and restricted to authorized personnel only.