CVE-2001-0381 in OpenPGP
Summary
by MITRE
The OpenPGP PGP standard allows an attacker to determine the private signature key via a cryptanalytic attack in which the attacker alters the encrypted private key file and captures a single message signed with the signature key.
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Analysis
by VulDB Data Team • 04/08/2019
The vulnerability described in CVE-2001-0381 represents a significant weakness in the OpenPGP PGP standard that exposes private signature keys to cryptographic analysis through a carefully crafted attack vector. This flaw operates within the cryptographic framework of digital signatures and key management systems, where the security model relies on the assumption that private keys remain uncompromised through normal operational procedures. The vulnerability specifically targets the signature key generation and verification processes within the OpenPGP implementation, creating a pathway for adversaries to extract sensitive cryptographic material through mathematical analysis rather than traditional brute force methods.
The technical mechanism behind this vulnerability involves an attacker who can modify the encrypted private key file and subsequently capture a single message that was signed using the compromised signature key. This attack leverages the mathematical properties of the RSA algorithm or other signature schemes used in OpenPGP implementations, where the attacker can use the modified encrypted key and the captured signature to perform cryptanalytic operations. The flaw stems from insufficient protection mechanisms that should prevent such modifications from yielding information about the underlying private key material, as outlined in the cryptographic principles defined by standards such as fips 186 and the corresponding security requirements for digital signature algorithms.
The operational impact of this vulnerability extends beyond simple key compromise, as it fundamentally undermines the trust model that digital signatures rely upon in secure communications. When an attacker successfully extracts a private signature key through this method, they gain the ability to forge signatures that appear authentic to any recipient who trusts the public key associated with that signature. This creates a cascading security risk where the compromise of a single signature key can lead to unauthorized authentication, data integrity violations, and potential system infiltration. The vulnerability particularly affects systems that rely heavily on OpenPGP for email security, code signing, and document authentication, as demonstrated in various penetration testing scenarios documented in the cybersecurity community.
This vulnerability aligns with several categories within the Common Weakness Enumeration framework, specifically mapping to CWE-310 Cryptographic Issues and CWE-311 Missing Encryption of Sensitive Data, as it exposes private cryptographic keys through insufficient protection mechanisms. The attack pattern corresponds to techniques described in the MITRE ATT&CK framework under the T1552.004 credential access tactic, where adversaries exploit weaknesses in cryptographic implementations to extract sensitive information. Organizations implementing OpenPGP solutions must consider the implications of this vulnerability when establishing security policies and cryptographic key management procedures, as the attack requires only a single interaction with the system rather than extended monitoring or resource-intensive operations.
Mitigation strategies for this vulnerability involve implementing proper cryptographic key protection mechanisms, including the use of secure key storage systems that prevent modification of encrypted key files and ensure that any alterations are detected and prevented. Organizations should employ additional cryptographic protections such as key derivation functions and proper random number generation to prevent the mathematical relationships that enable this attack. The implementation of proper key management protocols, including regular key rotation and the use of hardware security modules for key storage, provides additional defense layers against such cryptanalytic attacks. Security audits and penetration testing should specifically target cryptographic implementations to identify similar weaknesses in other signature and encryption systems that may be susceptible to analogous attacks.