CVE-2019-12422 in Shiro
Summary
by MITRE
Apache Shiro before 1.4.2, when using the default "remember me" configuration, cookies could be susceptible to a padding attack.
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Analysis
by VulDB Data Team • 11/19/2019
Apache Shiro versions prior to 1.4.2 contain a critical cryptographic vulnerability in their default "remember me" functionality that exposes applications to padding oracle attacks. This vulnerability stems from the insecure handling of encrypted cookie data where the framework employs a deterministic encryption approach without proper authentication mechanisms. The flaw allows attackers to manipulate encrypted cookie values and perform padding attacks to decrypt sensitive information or even execute arbitrary code within the application context.
The technical implementation of this vulnerability resides in Shiro's DefaultCipherService which uses a fixed initialization vector and deterministic encryption algorithms when processing remember me cookies. This creates predictable ciphertext patterns that can be exploited through padding oracle attacks where an attacker can submit modified cookie values and observe response differences to gradually decrypt the original data. The vulnerability is particularly dangerous because it affects the default configuration, meaning that applications using Shiro without explicit security hardening are automatically exposed to this risk. This weakness directly maps to CWE-327 which addresses the use of weak cryptographic algorithms and improper implementation of cryptographic functions, specifically targeting the lack of authenticated encryption.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable full application compromise. An attacker who successfully exploits this padding oracle vulnerability can decrypt session information stored in remember me cookies, potentially gaining access to privileged user sessions or extracting sensitive application data. The attack surface is particularly broad since the vulnerability affects all applications using Shiro's default remember me implementation without requiring any special conditions or user interaction. This makes it a particularly attractive target for automated exploitation tools and increases the risk of widespread compromise across multiple applications using the framework.
Security mitigations for this vulnerability require immediate patching to Apache Shiro version 1.4.2 or later where the framework properly implements authenticated encryption for remember me cookies. Organizations should also review their custom configurations to ensure they are not using the vulnerable default settings and implement proper cryptographic practices such as using random initialization vectors and authenticated encryption modes. The fix addresses the root cause by implementing proper padding oracle resistance through the use of authenticated encryption algorithms that prevent the deterministic encryption patterns that enabled the attack. This aligns with security best practices outlined in the OWASP Top 10 2017 and ATT&CK technique T1552.001 which covers credentials from password storage and credential access, as the vulnerability essentially allows attackers to extract and manipulate stored credentials through cryptographic weakness. Organizations should also consider implementing additional monitoring for unusual cookie manipulation patterns and ensure that all cryptographic implementations follow established security standards such as those defined in NIST SP 800-38A for block cipher modes of operation.