CVE-2012-3733 in iOS
Summary
by MITRE
Messages in Apple iOS before 6, when multiple iMessage e-mail addresses are configured, does not ensure that a reply s sender address matches the recipient address of the original message, which allows remote attackers to obtain potentially sensitive information about alternate e-mail addresses in opportunistic circumstances by reading a reply.
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Analysis
by VulDB Data Team • 04/13/2021
The vulnerability described in CVE-2012-3733 represents a significant information disclosure flaw within Apple iOS messaging systems that existed prior to version 6. This weakness specifically affects the iMessage functionality when users have configured multiple email addresses within their messaging setup. The core issue stems from improper validation of sender addresses during the reply process, creating a scenario where attackers can exploit the messaging system to discover alternative email addresses associated with a user account. This vulnerability operates under the broader category of information disclosure vulnerabilities, which are classified under CWE-200 in the Common Weakness Enumeration framework, representing a fundamental security flaw that exposes sensitive data to unauthorized parties.
The technical implementation of this vulnerability occurs within the iMessage protocol handling mechanism where the system fails to properly validate that the sender address of a reply message matches the recipient address of the original message. When a user receives an iMessage sent to one of their configured email addresses, the system should verify that any reply originates from the same address that was originally targeted. However, in affected iOS versions, this validation check was either absent or insufficiently implemented, allowing attackers to craft replies that could reveal information about other email addresses configured on the device. This flaw specifically exploits the opportunistic nature of messaging interactions where attackers can observe message flows and potentially deduce additional email addresses through careful analysis of reply headers and routing information.
The operational impact of this vulnerability extends beyond simple address discovery, as it can enable attackers to map out a user's email address landscape and potentially identify additional targets for social engineering or phishing attacks. When multiple email addresses are configured for iMessage, the vulnerability allows an attacker to determine which addresses are actively associated with a user's account, providing valuable intelligence for targeting future attacks. This information disclosure can be particularly dangerous in corporate environments where users may have personal and professional email addresses configured, or in situations where users have multiple email accounts for different purposes. The vulnerability operates at the application layer and can be exploited remotely without requiring authentication, making it particularly concerning from a threat modeling perspective.
From a threat actor methodology standpoint, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the information gathering phase, specifically targeting the collection of email addresses and user identity information. The opportunistic nature of the attack means that attackers can exploit this flaw during normal message interactions without requiring complex setup or specialized tools. Security professionals should note that this vulnerability demonstrates the importance of proper input validation and address verification in messaging systems, particularly when dealing with multi-recipient scenarios. The fix implemented by Apple in iOS 6 involved strengthening the validation mechanism to ensure that reply messages properly verify the sender address against the original recipient address, thereby preventing the information disclosure that occurred in earlier versions. Organizations should consider this vulnerability as an example of how seemingly minor validation flaws can lead to significant information exposure, emphasizing the need for comprehensive security testing of messaging protocols and user identity handling mechanisms.