CVE-2007-1269 in OpenPGP
Summary
by MITRE
GNUMail 1.1.2 and earlier does not properly use the --status-fd argument when invoking GnuPG, which prevents GNUMail from visually distinguishing between signed and unsigned portions of OpenPGP messages with multiple components, which allows remote attackers to forge the contents of a message without detection.
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Analysis
by VulDB Data Team • 07/13/2021
The vulnerability identified as CVE-2007-1269 affects GNUMail version 1.1.2 and earlier implementations, representing a critical flaw in the OpenPGP message processing mechanism. This issue stems from improper handling of the --status-fd argument during GnuPG invocation, which fundamentally undermines the security assurances that digital signatures are meant to provide. The flaw specifically impacts the visual distinction capabilities within GNUMail's user interface, creating a scenario where users cannot reliably differentiate between signed and unsigned components of multi-part OpenPGP messages.
The technical root cause of this vulnerability lies in the incorrect implementation of the status file descriptor argument that GnuPG uses to communicate status information back to the calling application. When GNUMail invokes GnuPG with the --status-fd option, it fails to properly utilize the status information that GnuPG provides about message verification results. This misconfiguration means that GnuPG's status output, which should indicate whether specific parts of a message have been successfully verified against their signatures, is not being processed or displayed by the mail client. The vulnerability operates at the interface level between the mail client and the cryptographic engine, creating a gap in the verification process that attackers can exploit.
The operational impact of this vulnerability is severe as it allows remote attackers to manipulate OpenPGP messages without detection, effectively bypassing the integrity verification mechanisms that digital signatures are designed to enforce. An attacker can construct a message with multiple components where some portions are signed while others remain unsigned, and through careful manipulation of the message structure, can make it appear to the user that the entire message has been properly signed and verified. This creates a false sense of security for users who rely on GNUMail's signature verification features to ensure message authenticity and integrity.
This vulnerability aligns with CWE-200, which describes improper output handling that can lead to information disclosure, and represents a significant deviation from proper cryptographic implementation practices. The flaw also relates to ATT&CK technique T1566, which involves social engineering through forged communications, as the vulnerability enables attackers to create convincing but fraudulent message appearances. The security implications extend beyond simple message manipulation to include potential data integrity compromise and trust exploitation within communication systems that rely on OpenPGP signatures for verification.
The recommended mitigations for this vulnerability include immediate upgrading to GNUMail versions that properly implement the --status-fd argument handling, ensuring that all message components are correctly processed and displayed. Organizations should also implement additional verification mechanisms beyond client-side signature checking, such as manual verification procedures or alternative cryptographic verification tools. Security teams should conduct thorough assessments of their email security infrastructure to identify any other applications that might be similarly affected by improper GnuPG integration, and implement monitoring solutions that can detect anomalous message patterns that might indicate signature manipulation attempts.