CVE-2001-1016 in PGP
Summary
by MITRE
PGP Corporate Desktop before 7.1, Personal Security before 7.0.3, Freeware before 7.0.3, and E-Business Server before 7.1 does not properly display when invalid userID s are used to sign a message, which could allow an attacker to make the user believe that the document has been signed by a trusted third party by adding a second, invalid user ID to a key which has already been signed by the third party, aka the "PGPsdk Key Validity Vulnerability."
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Analysis
by VulDB Data Team • 06/04/2018
The vulnerability described in CVE-2001-1016 represents a significant weakness in the PGP encryption software ecosystem that affects multiple product lines including PGP Corporate Desktop, Personal Security, Freeware, and E-Business Server versions prior to their respective 7.1 or 7.0.3 releases. This flaw operates at the core of PGP's key validation and user identification mechanisms, specifically targeting how the software handles invalid user IDs within cryptographic signing processes. The vulnerability stems from inadequate validation of user identity information during message signing operations, creating a scenario where malicious actors can manipulate the visual presentation of digital signatures to deceive users.
The technical implementation of this vulnerability allows attackers to exploit the inconsistent handling of multiple user IDs within a single key structure. When a key contains both valid and invalid user IDs, the PGP software fails to properly distinguish between them during signature verification, leading to misleading visual indicators that suggest a document has been signed by a trusted third party. This occurs because the software's display logic does not adequately differentiate between legitimate and forged user identity information, particularly when an attacker adds an invalid user ID to a key that has already been legitimately signed by a trusted entity. The flaw essentially creates a false positive scenario where users cannot reliably determine the authenticity of a signature based on the visual indicators presented by the software.
From an operational perspective, this vulnerability poses a substantial risk to digital security protocols and trust mechanisms that organizations rely upon for secure communications. The ability to make users believe a document has been signed by a trusted third party creates opportunities for social engineering attacks, man-in-the-middle scenarios, and impersonation attempts that could compromise sensitive data exchanges. The impact extends beyond simple deception as it undermines the fundamental trust model that digital signatures are designed to establish. Users who cannot distinguish between legitimate and forged signatures may inadvertently trust documents that have been tampered with, potentially leading to unauthorized access to confidential information, fraudulent transactions, or compromised system integrity. This vulnerability particularly affects environments where PGP is used for email encryption, document signing, and secure communication protocols.
The security implications of this vulnerability align with several CWE classifications including CWE-295 for improper certificate validation and CWE-347 for improper certificate validation. The attack vector operates through the manipulation of key structures and user identity information, which can be analyzed through the ATT&CK framework under techniques related to credential access and defense evasion. Organizations using affected PGP versions should implement immediate mitigations including upgrading to patched versions, implementing additional verification procedures, and establishing more rigorous key management protocols. The vulnerability also highlights the importance of proper input validation and user interface design in cryptographic software, where visual indicators must accurately reflect the underlying security state rather than providing misleading information to users.
This flaw demonstrates the critical importance of robust validation mechanisms in cryptographic systems, where even seemingly minor implementation gaps can create significant security risks. The vulnerability underscores the need for comprehensive testing of user interface elements in security software, as visual deception can be more dangerous than technical bypasses. Organizations should consider implementing additional layers of verification beyond the basic PGP signature validation, including manual confirmation procedures and cross-referencing with known good keys. The incident also emphasizes the importance of maintaining up-to-date cryptographic software and implementing proper security governance policies that include regular vulnerability assessments and patch management procedures.