CVE-2016-4842 in Mailwise
Summary
by MITRE
Cybozu Mailwise before 5.4.0 allows remote attackers to obtain information on when an email is read.
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Analysis
by VulDB Data Team • 09/18/2020
The vulnerability identified as CVE-2016-4842 affects Cybozu Mailwise versions prior to 5.4.0, representing a significant information disclosure flaw that compromises user privacy and security. This issue resides within the email server software's handling of read receipts and tracking mechanisms, where remote attackers can exploit the system to determine when specific emails have been accessed by recipients. The vulnerability stems from insufficient validation and sanitization of email read tracking parameters, allowing malicious actors to intercept and analyze metadata associated with email delivery and consumption patterns. This type of information leakage can provide attackers with valuable intelligence about user behavior, communication patterns, and potentially sensitive operational timing data that could be leveraged for targeted attacks or social engineering campaigns.
The technical implementation of this vulnerability involves the improper handling of email read tracking features within the Mailwise platform. When emails are sent through the system, the software includes tracking mechanisms that monitor delivery and read status, but these mechanisms lack proper access controls and validation checks. Attackers can manipulate the tracking parameters or intercept the communication between email clients and the server to extract timing information about when messages are opened. This flaw typically manifests through crafted HTTP requests or by analyzing the response headers and tracking URLs embedded in email messages. The vulnerability is particularly concerning because it operates at the application layer and requires no special privileges or authentication to exploit, making it accessible to any remote attacker with network access to the affected system. The flaw aligns with CWE-200, which addresses information exposure, and represents a classic case of insufficient logging and monitoring that allows unauthorized parties to gather sensitive temporal data about user activities.
The operational impact of CVE-2016-4842 extends beyond simple privacy concerns to encompass broader security implications that can affect organizational security posture and user trust. When attackers can determine email read times, they gain insights into user availability patterns, communication habits, and potentially sensitive business operations timing. This information can be particularly damaging in corporate environments where the timing of email interactions may reveal strategic planning, security incidents, or confidential business activities. The vulnerability creates a persistent surveillance capability that can be exploited for reconnaissance purposes, allowing attackers to build detailed profiles of user behavior over time. Organizations may experience reputational damage when such information leaks occur, as users expect their email communications to remain private and secure. The vulnerability also creates opportunities for advanced persistent threats to establish long-term monitoring capabilities, as attackers can use the timing data to correlate with other attack vectors or to determine optimal times for launching more sophisticated attacks. From an ATT&CK framework perspective, this vulnerability maps to techniques involving reconnaissance and credential access, as it enables adversaries to gather intelligence that can be used to refine their attack strategies and increase success rates.
Mitigation strategies for CVE-2016-4842 primarily focus on updating the affected Mailwise software to version 5.4.0 or later, which includes proper validation and access controls for read tracking features. Organizations should also implement network monitoring to detect unusual patterns in email tracking requests and consider disabling read receipt functionality if it is not essential for business operations. Security administrators should review email server configurations to ensure that tracking mechanisms are properly secured and that access controls are appropriately enforced. Additionally, implementing network segmentation and firewall rules to restrict access to email tracking endpoints can help reduce the attack surface. Regular security assessments and vulnerability scanning should include checks for similar issues in other email systems and applications that may exhibit comparable behavior. The remediation process should also involve educating users about the potential risks of email tracking features and the importance of maintaining updated security software. Organizations should establish monitoring procedures to detect unauthorized access attempts to email tracking systems and maintain audit logs of email system activities to identify potential exploitation attempts. The vulnerability serves as a reminder of the importance of secure coding practices and the need for regular security updates in email infrastructure components.