CVE-2015-5841 in Watch
Summary
by MITRE
The CFNetwork Proxies component in Apple iOS before 9 does not properly handle a Set-Cookie header within a response to an HTTP CONNECT request, which allows remote proxy servers to conduct cookie-injection attacks via a crafted response.
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Analysis
by VulDB Data Team • 11/21/2024
The vulnerability identified as CVE-2015-5841 resides within Apple iOS versions prior to 9.0, specifically affecting the CFNetwork Proxies component that handles HTTP communication through proxy servers. This flaw represents a critical security issue that enables malicious proxy servers to inject arbitrary cookies into HTTP responses, potentially compromising user sessions and data confidentiality. The vulnerability manifests when the system processes a Set-Cookie header within a response to an HTTP CONNECT request, which is typically used for establishing secure connections through proxy servers.
The technical exploitation of this vulnerability occurs through a specific handling mechanism within iOS's network stack where the CFNetwork component fails to properly validate or sanitize Set-Cookie headers in proxy responses. When an HTTP CONNECT request is made through a proxy server, the proxy may return a response containing a Set-Cookie header that gets improperly processed by iOS. This behavior creates a path for attackers to inject malicious cookies that could be interpreted by the browser or application as legitimate session cookies, thereby enabling session hijacking or cross-site scripting attacks. The flaw essentially allows attackers to manipulate the cookie jar of applications that rely on proxy connections, creating persistent unauthorized access vectors.
From an operational impact perspective, this vulnerability poses significant risks to users of affected iOS versions who frequently use proxy servers for network connectivity. The cookie injection capability can be exploited by attackers positioned between the user and the target server, particularly in public Wi-Fi networks or corporate environments where proxy servers are commonly deployed. This vulnerability directly violates the principle of secure cookie handling as defined in web security standards and can lead to unauthorized access to user accounts, data exfiltration, and session manipulation across various web applications that rely on cookie-based authentication. The attack vector is particularly dangerous because it operates at the network protocol level, making it difficult to detect through traditional application-level security measures.
The vulnerability aligns with CWE-1004, which addresses insecure cookie handling practices, and maps to ATT&CK technique T1187 for bypassing network restrictions through proxy manipulation. Organizations should implement immediate mitigations including upgrading to iOS 9.0 or later versions where this vulnerability is patched, deploying network monitoring solutions to detect anomalous Set-Cookie header behaviors, and configuring proxy server configurations to sanitize or remove Set-Cookie headers from CONNECT responses. Additionally, network administrators should consider implementing web application firewalls that can detect and block suspicious cookie injection patterns. The patch released by Apple addresses the core issue by strengthening the validation mechanisms within the CFNetwork component to properly handle Set-Cookie headers in proxy responses, thereby preventing the injection of malicious cookies that could compromise user sessions and network security.