CVE-2015-1067 in Watch OS
Summary
by MITRE
Secure Transport in Apple iOS before 8.2, Apple OS X through 10.10.2, and Apple TV before 7.1 does not properly restrict TLS state transitions, which makes it easier for remote attackers to conduct cipher-downgrade attacks to EXPORT_RSA ciphers via crafted TLS traffic, related to the "FREAK" issue, a different vulnerability than CVE-2015-0204 and CVE-2015-1637.
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Analysis
by VulDB Data Team • 05/19/2022
The vulnerability described in CVE-2015-1067 represents a critical flaw in Apple's Secure Transport implementation that affects multiple operating systems including iOS versions prior to 8.2, macOS versions through 10.10.2, and Apple TV versions before 7.1. This issue stems from improper handling of TLS state transitions within the cryptographic library, creating a pathway for sophisticated man-in-the-middle attacks that specifically target the downgrade of encryption strength. The vulnerability is categorized under CWE-327, which addresses the use of weak or broken cryptographic algorithms, and more specifically aligns with the broader category of improper restriction of cryptographic protocols that undermines the security assurances typically provided by TLS implementations.
The technical flaw manifests when Secure Transport accepts certain TLS handshake messages that permit transitions to weaker cryptographic states, particularly allowing the negotiation of EXPORT_RSA ciphers which were originally designed for export restrictions in the early days of internet encryption. This behavior enables attackers to perform what is known as a cipher-downgrade attack, where they force the connection to use weaker cryptographic algorithms that are more susceptible to brute-force attacks. The vulnerability is specifically related to the FREAK (Factoring RSA Export Keys) attack vector, which exploits the presence of weak export-grade cryptography in TLS implementations, making it possible for adversaries to intercept and decrypt communications that should have been protected by modern encryption standards.
The operational impact of this vulnerability is severe as it allows remote attackers to conduct active attacks against secured communications without requiring any special privileges or physical access to the affected systems. The downgrade attack can be executed over the network by intercepting TLS handshakes and manipulating the cryptographic negotiation process to force the use of EXPORT_RSA ciphers, which have key sizes as small as 512 bits and can be broken with sufficient computational resources. This creates a significant risk for sensitive data transmission including web browsing sessions, email communications, and any application layer protocols that rely on TLS for security. The attack vector aligns with ATT&CK technique T1573.001 which describes the use of TLS/SSL protocol manipulation to bypass security controls.
Mitigation strategies for this vulnerability require immediate patching of affected systems with the respective security updates from Apple, which address the improper TLS state transition handling in Secure Transport. Organizations should also implement network monitoring to detect unusual TLS handshake patterns that might indicate attempted downgrade attacks, and consider deploying additional security layers such as certificate pinning or mandatory use of stronger cipher suites. The fix implemented by Apple in subsequent releases involved tightening the validation of TLS handshake parameters and eliminating the ability to negotiate weak cryptographic algorithms, particularly those that were historically restricted for export purposes. Security teams should also conduct thorough vulnerability assessments to identify any custom applications or services that might be using deprecated cryptographic libraries and ensure that all systems are updated to prevent exploitation of this and similar vulnerabilities that could compromise the integrity of encrypted communications.