CVE-2015-1091 in MacOS X
Summary
by MITRE
The CFNetwork Session component in Apple iOS before 8.3 and Apple OS X before 10.10.3 does not properly handle request headers during processing of redirects in HTTP responses, which allows remote attackers to bypass the Same Origin Policy via a crafted web site.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability identified as CVE-2015-1091 resides within Apple's CFNetwork Session component that governs how iOS and macOS handle HTTP requests and responses. This flaw specifically manifests during the redirect processing phase of HTTP communications, where the system fails to adequately validate or sanitize request headers that are transmitted across different origins. The issue affects versions of iOS prior to 8.3 and OS X prior to 10.10.3, representing a significant window of affected operating systems that were widely deployed in enterprise and consumer environments. The vulnerability stems from improper handling of HTTP redirect mechanisms that should normally enforce strict origin policies to prevent unauthorized cross-origin resource access.
The technical exploitation of this vulnerability occurs when a malicious web server crafts HTTP redirect responses that contain specially crafted headers designed to bypass the browser's Same Origin Policy enforcement mechanisms. When a user's device processes these redirects, the CFNetwork component incorrectly propagates these headers across origin boundaries, effectively allowing an attacker to inject content or modify request parameters that should be restricted by security policies. This behavior creates a path for attackers to perform cross-origin resource sharing attacks where they can access resources that would normally be protected by the same origin policy. The flaw operates at the protocol level within the network stack, making it particularly insidious as it can be exploited without requiring user interaction beyond visiting a malicious website.
From an operational impact perspective, this vulnerability enables attackers to circumvent fundamental web security protections that are critical for maintaining user privacy and application security. The ability to bypass the Same Origin Policy creates opportunities for session hijacking, cross-site scripting attacks, and data exfiltration from applications that rely on proper origin enforcement. Security researchers have categorized this vulnerability under CWE-346, which addresses "Improper Verification of Source of a Communication Channel" and aligns with ATT&CK technique T1071.004 for application layer protocol tunneling. The vulnerability's impact extends beyond simple information disclosure, as it can enable more sophisticated attacks including credential theft and privilege escalation within web applications that depend on origin-based security controls.
Organizations affected by this vulnerability should prioritize immediate deployment of Apple's security patches for iOS 8.3 and OS X 10.10.3, which address the improper header handling during HTTP redirect processing. System administrators should also implement network monitoring to detect anomalous redirect behaviors and consider deploying web application firewalls that can identify and block suspicious header patterns. The mitigation strategy should include regular security assessments of web applications to ensure proper origin policy enforcement and implementation of additional security headers such as Content Security Policy to provide defense-in-depth. Organizations should also conduct security awareness training to educate users about the risks of visiting untrusted websites that could exploit this vulnerability during normal browsing activities.