CVE-2015-8013 in OpenPGP.js
Summary
by MITRE
s2k.js in OpenPGP.js will decrypt arbitrary messages regardless of passphrase for crafted PGP keys which allows remote attackers to bypass authentication if message decryption is used as an authentication mechanism via a crafted symmetrically encrypted PGP message.
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Analysis
by VulDB Data Team • 12/14/2022
The vulnerability identified as CVE-2015-8013 resides within the s2k.js component of OpenPGP.js, a popular JavaScript implementation of the OpenPGP standard. This flaw represents a critical security weakness that fundamentally undermines the cryptographic integrity of the system by allowing unauthorized decryption of sensitive information. The vulnerability specifically affects the handling of symmetrically encrypted PGP messages where the passphrase validation mechanism fails to properly verify the authenticity of the provided credentials. When attackers craft malicious PGP keys with specific parameters, they can exploit this weakness to decrypt messages without possessing the correct passphrase, effectively bypassing the intended authentication controls that should protect the encrypted data.
The technical implementation of this vulnerability stems from improper validation of the key derivation function within the s2k.js module. According to CWE-287, this represents an improper authentication flaw where the system fails to properly verify the identity of the entity attempting to access encrypted resources. The flaw occurs during the symmetric key processing phase where the implementation does not adequately verify the passphrase against the derived key material, allowing crafted inputs to bypass the normal authentication flow. This vulnerability operates at the core of the cryptographic protocol implementation, specifically targeting the password-based key derivation mechanisms that are fundamental to OpenPGP's security model.
The operational impact of CVE-2015-8013 is severe and far-reaching, particularly in environments where OpenPGP.js is used for authentication purposes. When message decryption serves as an authentication mechanism, this vulnerability creates a backdoor that allows remote attackers to gain unauthorized access to sensitive information without proper authorization. The attack vector is particularly dangerous because it requires no local privileges or specialized equipment - attackers can simply craft malicious PGP messages and submit them to systems using OpenPGP.js for decryption operations. This vulnerability directly maps to ATT&CK technique T1552.004, which involves unsecured credentials, as it allows attackers to bypass authentication controls through improper handling of passphrase validation.
Systems utilizing OpenPGP.js for secure communications, email encryption, or authentication mechanisms are at significant risk when this vulnerability exists. The impact extends beyond simple data exposure to include potential compromise of entire communication channels where trust is established through cryptographic verification. Organizations relying on this library for sensitive data protection, such as healthcare providers, financial institutions, or government agencies, face critical security implications when this vulnerability remains unpatched. The vulnerability demonstrates how subtle flaws in cryptographic implementation can have devastating consequences for the overall security posture of systems that depend on proper authentication mechanisms.
Mitigation strategies for CVE-2015-8013 require immediate patching of the OpenPGP.js library to address the flawed key derivation function in s2k.js. Organizations should implement comprehensive monitoring to detect potential exploitation attempts and establish network segmentation to limit the impact of successful attacks. Security teams must conduct thorough assessments of all systems utilizing OpenPGP.js to identify vulnerable components and ensure proper key management practices are implemented. Additionally, the vulnerability highlights the importance of proper cryptographic library auditing and the need for rigorous security testing of cryptographic implementations before deployment. Organizations should also consider implementing additional authentication layers and monitoring mechanisms to detect unauthorized decryption attempts, as the vulnerability fundamentally weakens the authentication controls that should protect sensitive communications.