CVE-2014-4439 in Mac OS X
Summary
by MITRE
Mail in Apple OS X before 10.10 does not properly recognize the removal of a recipient address from a message, which makes it easier for remote attackers to obtain sensitive information in opportunistic circumstances by reading a message intended exclusively for other recipients.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 02/23/2022
The vulnerability identified as CVE-2014-4439 represents a significant information disclosure flaw within Apple's Mail application affecting operating systems prior to version 10.10. This weakness stems from the application's improper handling of recipient address modifications during message composition, creating a scenario where sensitive communication can be inadvertently accessed by unauthorized parties. The vulnerability specifically manifests when a user removes a recipient address from a message before sending, yet the application fails to completely purge the corresponding address information from the message headers or body, leaving residual data that could be exploited by malicious actors.
From a technical perspective, this vulnerability operates as a classic case of information exposure through improper data handling during message processing. The flaw occurs within the Mail application's message composition and transmission logic where recipient address removal is not properly synchronized with the underlying message structure. When a user removes a recipient, the application should completely eliminate all references to that address from the message metadata, including header fields such as To, Cc, and Bcc. However, the implementation fails to perform this complete cleanup, resulting in the persistence of address information that could be extracted by attackers who intercept or gain access to the message during transmission or storage phases.
The operational impact of this vulnerability extends beyond simple information disclosure, creating potential risks for privacy and security in environments where sensitive communications are routine. Attackers can exploit this weakness by analyzing message headers or content to identify the original recipient addresses that were subsequently removed, potentially gaining insights into communication patterns, personnel structures, or confidential information flows. This vulnerability particularly affects organizations that rely heavily on email-based communication for sensitive operations, as the exposure of recipient information could lead to targeted attacks, social engineering attempts, or unauthorized access to confidential data flows.
The vulnerability aligns with CWE-200, which describes improper information exposure, and demonstrates characteristics consistent with ATT&CK technique T1566, specifically the use of spearphishing attachments or links to gain initial access. The opportunistic nature of the attack means that the vulnerability can be exploited without requiring sophisticated targeting or advanced technical skills, making it particularly dangerous in environments where email monitoring or interception is possible. Security practitioners should note that this vulnerability highlights the importance of proper data sanitization and the need for comprehensive testing of message handling processes, especially when dealing with sensitive information.
Mitigation strategies for CVE-2014-4439 primarily involve upgrading to Apple OS X version 10.10 or later, where the issue has been resolved through improved message processing and address handling mechanisms. Organizations should also implement additional security controls such as email encryption protocols, secure email gateways, and monitoring systems to detect unusual recipient address patterns or message anomalies. Network administrators should consider deploying email security solutions that can identify and flag potentially problematic messages, while also ensuring that all users receive security awareness training regarding the risks of sending sensitive information through email systems. The remediation process should include thorough testing of email applications and verification that address removal functions properly eliminate all references to removed recipients from message metadata.