CVE-2000-1138 in Lotus Notes
Summary
by MITRE
Lotus Notes R5 client R5.0.5 and earlier does not properly warn users when an S/MIME email message has been modified, which could allow an attacker to modify the email in transit without being detected.
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Analysis
by VulDB Data Team • 04/07/2019
The vulnerability described in CVE-2000-1138 affects the Lotus Notes R5 client version 5.0.5 and earlier, specifically targeting the S/MIME email security implementation within the application. This weakness represents a critical flaw in the email client's integrity verification mechanisms, where the system fails to properly alert users when S/MIME signed messages have been tampered with during transit. The issue stems from inadequate validation procedures that should have detected modifications to encrypted email content, creating a false sense of security for users who rely on S/MIME signatures for message authenticity.
The technical flaw manifests in the client's failure to perform proper cryptographic validation of S/MIME messages, particularly when the digital signature verification process does not adequately detect tampering or modification attempts. When an attacker intercepts an S/MIME signed email message, they can potentially alter the content without triggering any warning indicators in the Lotus Notes interface. This vulnerability directly impacts the fundamental security properties of message integrity and authentication that S/MIME is designed to provide, allowing for man-in-the-middle attacks where modified content appears legitimate to the recipient.
The operational impact of this vulnerability extends beyond simple message modification, as it undermines the trust model that organizations rely upon when implementing S/MIME security protocols. Users who receive S/MIME signed emails may unknowingly accept altered content, potentially leading to the execution of malicious commands, the disclosure of sensitive information, or the acceptance of fraudulent communications. This weakness particularly affects organizations that depend on S/MIME for secure email communications, as it creates a scenario where security controls appear to function properly while actually providing no protection against content modification attacks. The vulnerability allows attackers to exploit the trust relationship between sender and recipient, potentially leading to data breaches, financial fraud, or other malicious activities that leverage the false security provided by the S/MIME signature.
From a cybersecurity perspective, this vulnerability aligns with CWE-310, which addresses cryptographic issues related to the failure of cryptographic implementations to properly validate data integrity. The weakness also connects to ATT&CK technique T1566, which covers social engineering tactics involving the manipulation of email content. Organizations should implement immediate mitigations including upgrading to patched versions of Lotus Notes, implementing additional email security measures beyond S/MIME, and establishing user awareness training about the limitations of digital signatures. The vulnerability highlights the importance of proper cryptographic validation and the need for robust integrity checking mechanisms in email security implementations, emphasizing that security controls must be comprehensive and validated against various attack vectors.