CVE-2012-3730 in iOS
Summary
by MITRE
Mail in Apple iOS before 6 does not properly handle reuse of Content-ID header values, which allows remote attackers to spoof attachments via a header value that was also used in a previous e-mail message, as demonstrated by a message from a different sender.
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Analysis
by VulDB Data Team • 04/13/2021
The vulnerability described in CVE-2012-3730 represents a critical flaw in Apple iOS email handling mechanisms that stems from improper validation of Content-ID header values within email messages. This issue affects iOS versions prior to version 6 and specifically targets the email client's interpretation of multipart email structures where Content-ID headers are used to identify attachments and embedded resources. The flaw operates at the application layer of the email processing stack, where the iOS email client fails to properly distinguish between legitimate and malicious reuse of Content-ID values across different email messages from different senders.
The technical implementation of this vulnerability exploits a fundamental weakness in how iOS email clients process multipart email messages containing Content-ID headers. When an email client encounters a Content-ID header value, it typically uses this identifier to associate attachments with their corresponding embedded resources within the email message. However, iOS versions before 6 did not properly validate whether a Content-ID value was being reused from a previous message, allowing attackers to craft malicious emails that reference Content-ID values previously used in legitimate messages. This creates a scenario where an attacker can manipulate the email client's interpretation of attachment relationships, effectively enabling them to spoof or manipulate the display of attachments in ways that bypass normal email security checks.
From an operational perspective, this vulnerability presents significant security implications for users of affected iOS devices who receive email messages from untrusted sources. Attackers can leverage this flaw to create convincing phishing emails or malicious attachments that appear to be legitimate documents or files from trusted senders. The attack vector requires the victim to simply open the malicious email message, making it particularly dangerous as it does not require any special user interaction beyond normal email reading behavior. This vulnerability directly impacts email security protocols and can be classified under CWE-224, which addresses improper handling of security-relevant information in email systems.
The attack pattern associated with CVE-2012-3730 aligns with several techniques documented in the MITRE ATT&CK framework, particularly those related to social engineering and credential access through email-based attacks. The vulnerability enables threat actors to perform email spoofing operations that can bypass standard email validation mechanisms, potentially leading to successful phishing campaigns or malware delivery. The impact extends beyond simple message manipulation to include potential privilege escalation scenarios where attackers could exploit the flawed Content-ID handling to inject malicious content into email messages that appear legitimate to end users.
Security mitigations for this vulnerability primarily involve upgrading to iOS version 6 or later, which includes proper validation of Content-ID header reuse. Organizations should also implement email security solutions that can detect and filter suspicious email patterns, particularly those involving unusual Content-ID header usage. Network administrators should consider implementing email filtering rules that can identify and quarantine messages with suspicious Content-ID reuse patterns. Additionally, user education programs should emphasize the importance of verifying email sources and not automatically trusting attachments in emails from unknown senders, even when they appear to come from legitimate sources. The vulnerability demonstrates the importance of proper input validation in email processing systems and highlights the need for robust security measures at all layers of email handling, from network transport to application-level processing.