CVE-2016-4747 in iOS
Summary
by MITRE
Mail in Apple iOS before 10 mishandles certificates, which makes it easier for man-in-the-middle attackers to discover mail credentials via unspecified vectors.
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Analysis
by VulDB Data Team • 09/16/2022
The vulnerability identified as CVE-2016-4747 affects Apple iOS versions prior to 10.0, specifically within the Mail application's certificate handling mechanisms. This flaw represents a significant security weakness that undermines the integrity of email communications by creating opportunities for attackers to intercept and exploit authentication credentials. The issue stems from improper certificate validation processes that fail to adequately verify the authenticity and trustworthiness of digital certificates used in email encryption and authentication protocols.
The technical implementation of this vulnerability lies in how iOS Mail processes certificate chains and validation procedures during secure email communication establishment. When users configure email accounts with encryption protocols such as SSL/TLS, the system should rigorously validate certificate authorities and ensure proper certificate chain integrity. However, the flawed implementation allows for certificate validation bypasses that enable attackers to manipulate the certificate trust verification process. This weakness creates a pathway for man-in-the-middle attacks where malicious actors can intercept email communications and potentially extract sensitive authentication information including usernames and passwords.
The operational impact of CVE-2016-4747 extends beyond simple credential theft, as it compromises the fundamental security assumptions of email encryption. Attackers exploiting this vulnerability can establish fraudulent connections that appear legitimate to end users, making detection extremely difficult. The unspecified vectors mentioned in the description suggest that multiple attack scenarios may be possible, including certificate pinning bypasses, trust store manipulation, or improper certificate revocation checking. This vulnerability affects not only individual users but also enterprise environments where email security is critical for business operations and data protection.
Organizations and users should implement immediate mitigations including upgrading to iOS 10.0 or later versions where the vulnerability has been addressed through improved certificate validation routines. Network administrators should also consider implementing additional monitoring for suspicious certificate validation events and establish enhanced email security policies. The vulnerability aligns with CWE-295 which addresses improper certificate validation, and maps to ATT&CK technique T1566 related to credential harvesting through phishing and man-in-the-middle attacks. Security professionals should also consider deploying email encryption solutions that provide additional layers of protection beyond what the operating system certificate validation can provide, ensuring that even if the iOS vulnerability is exploited, the underlying email data remains protected through alternative encryption mechanisms.