CVE-2015-5859 in iOS
Summary
by MITRE
The CFNetwork HTTPProtocol component in Apple iOS before 9 does not properly recognize the HSTS preload list during a private-browsing session, which makes it easier for remote attackers to obtain sensitive information by sniffing the network.
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Analysis
by VulDB Data Team • 05/10/2018
The vulnerability identified as CVE-2015-5859 resides within Apple iOS versions prior to 9.0, specifically affecting the CFNetwork HTTPProtocol component that handles web communications. This flaw represents a significant security weakness in the browser's handling of HTTP Strict Transport Security mechanisms, particularly during private browsing sessions where users expect enhanced privacy protections. The issue stems from the component's failure to properly consult the HSTS preload list when processing web requests within private browsing contexts, creating a potential attack vector for man-in-the-middle operations.
The technical nature of this vulnerability involves the improper implementation of HSTS (HTTP Strict Transport Security) enforcement mechanisms within Apple's mobile operating system. HSTS is a security feature designed to prevent protocol downgrade attacks and cookie hijacking by instructing browsers to only communicate over HTTPS with websites. When the CFNetwork component fails to reference the HSTS preload list during private browsing sessions, it allows attackers to potentially intercept and manipulate traffic that should otherwise be protected by strict transport security policies. This misconfiguration effectively undermines the security guarantees that private browsing sessions are supposed to provide.
The operational impact of CVE-2015-5859 is particularly concerning as it enables remote attackers to conduct passive network sniffing operations and potentially obtain sensitive information from users engaged in private browsing activities. Attackers can exploit this vulnerability by intercepting network traffic between iOS devices and web servers, particularly when users are accessing sensitive websites or performing transactions. The vulnerability is especially dangerous in public network environments such as coffee shops, airports, or other locations where network sniffing is common, as it removes the expected privacy protections that private browsing sessions are designed to provide.
This vulnerability aligns with CWE-310, which addresses cryptographic weaknesses in the implementation of security protocols, and relates to ATT&CK technique T1566 for phishing and credential theft. The flaw represents a critical gap in Apple's implementation of security best practices, particularly in the area of secure communication protocols and privacy protection mechanisms. Organizations and individuals using affected iOS versions face increased risk of data interception and potential credential compromise, as the security controls that should protect against such attacks are rendered ineffective during private browsing sessions.
The recommended mitigation strategy involves immediate upgrading to iOS 9.0 or later versions where this vulnerability has been addressed through proper implementation of HSTS preload list checking. Additionally, users should avoid conducting sensitive activities over untrusted networks, particularly when using private browsing modes, and organizations should implement additional network monitoring and intrusion detection measures to identify potential exploitation attempts. Security teams should also consider deploying network security solutions that can detect and alert on unusual traffic patterns that might indicate exploitation of this vulnerability.