CVE-2006-3778 in Lotus Notes
Summary
by MITRE
IBM Lotus Notes 6.0, 6.5, and 7.0 does not properly handle replies to e-mail messages with alternate name users when the (1) "Save As Draft" option is used or (2) a "," (comma) is inside the "phrase" portion of an address, which can cause the e-mail to be sent to users that were deleted from the To, CC, and BCC fields, which allows remote attackers to obtain the list of original recipients.
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Analysis
by VulDB Data Team • 04/21/2017
The vulnerability described in CVE-2006-3778 represents a significant information disclosure flaw within IBM Lotus Notes email client versions 6.0, 6.5, and 7.0. This issue stems from improper handling of email message replies when specific conditions are met, creating a scenario where deleted recipients can still receive messages intended for original recipients. The flaw operates through two distinct mechanisms that exploit weaknesses in the email processing logic of the Lotus Notes client software. The vulnerability specifically affects the client-side handling of email addresses during reply operations, particularly when the "Save As Draft" functionality is utilized or when commas appear within the phrase portion of email addresses.
The technical root cause of this vulnerability lies in the flawed parsing and validation of email address formats within the Lotus Notes client's reply processing mechanism. When users compose replies to emails that contain alternate name users, the software fails to properly validate or sanitize the recipient fields, particularly when dealing with complex address formats that include commas within the phrase portion of addresses. This parsing error occurs during the reply generation process where the system incorrectly maintains references to deleted recipients in the To, CC, and BCC fields. The vulnerability operates at the application layer and demonstrates poor input validation and sanitization practices that are classified under CWE-20, which represents "Improper Input Validation" in the Common Weakness Enumeration catalog. The issue manifests as a failure to properly handle edge cases in email address parsing, particularly when dealing with comma-separated values within address phrases.
The operational impact of this vulnerability is substantial as it enables remote attackers to obtain information about the original recipients of email messages without requiring any special privileges or authentication. This information disclosure occurs because the system continues to reference deleted recipients in the reply process, effectively allowing attackers to determine the original recipient list of messages. The vulnerability creates a reconnaissance opportunity for attackers who can use this information to identify potential targets or gather intelligence about the organization's communication patterns. From an attacker's perspective, this flaw represents a low-effort method for conducting passive reconnaissance activities, as it does not require direct exploitation of the system but rather takes advantage of the software's improper handling of email addresses. The impact aligns with ATT&CK technique T1592, which involves reconnaissance activities to gather information about targets, and T1071.004, which covers application layer protocol usage for information gathering.
The vulnerability can be exploited by remote attackers who do not need to authenticate to the system to gain access to recipient information, making it particularly concerning for organizations that rely on Lotus Notes for sensitive communications. The flaw is particularly dangerous because it operates silently in the background, with no visible error messages or system warnings to alert users or administrators to the information disclosure occurring. The security implications extend beyond simple information gathering, as the revealed recipient lists could provide attackers with insights into organizational structures, communication patterns, and potentially sensitive business relationships. Organizations using these older versions of Lotus Notes face a significant risk profile due to the lack of proper input validation and the potential for attackers to construct detailed profiles of communication networks within their organizations.
Mitigation strategies for this vulnerability should focus on immediate software updates and patches provided by IBM, as well as implementing additional network monitoring to detect unusual email processing patterns. Organizations should consider implementing email content filtering rules that can identify and block messages containing problematic address formats, particularly those with commas in phrase portions. The recommended approach includes upgrading to supported versions of Lotus Notes where this vulnerability has been addressed, as well as implementing proper email security policies that include regular vulnerability assessments and security audits of email systems. Additionally, administrators should consider disabling or restricting the "Save As Draft" functionality in environments where this vulnerability poses a significant risk, and implementing network-based intrusion detection systems to monitor for potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper input validation and sanitization in email processing applications, particularly in enterprise environments where sensitive information flows through complex communication systems.