CVE-2012-3696 in iOS
Summary
by MITRE
CRLF injection vulnerability in WebKit in Apple Safari before 6.0 allows remote attackers to inject arbitrary HTTP headers and conduct HTTP request splitting attacks via a crafted web site that leverages improper WebSockets URI handling.
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Analysis
by VulDB Data Team • 01/04/2025
The CVE-2012-3696 vulnerability represents a critical CRLF injection flaw in Apple Safari's WebKit rendering engine affecting versions prior to 6.0. This vulnerability stems from improper handling of WebSocket URIs that contain carriage return line feed sequences, enabling attackers to inject malicious HTTP headers into web requests. The flaw exists within the WebSocket protocol implementation where the browser fails to properly sanitize URI components before establishing connections, creating an avenue for header injection attacks that can be exploited across the entire HTTP stack. This vulnerability operates at the application layer and specifically targets the HTTP protocol handling mechanisms within Safari's WebKit engine, making it particularly dangerous due to Safari's widespread adoption across macOS and iOS platforms.
The technical implementation of this vulnerability exploits the improper parsing of WebSocket URIs where CRLF characters are not adequately filtered or escaped during URI validation. When a malicious website constructs a WebSocket URI containing embedded carriage return and line feed sequences, the WebKit engine processes these sequences as literal characters rather than URI delimiters, allowing attackers to inject additional HTTP headers that get appended to the actual HTTP request. This creates a scenario where attackers can manipulate the HTTP header fields of requests, potentially enabling session hijacking, cache poisoning, or cross-site request forgery attacks. The vulnerability specifically leverages the WebSocket protocol's URI parsing logic, which should have validated and sanitized URI components before establishing connections to remote servers, but instead passes malformed URIs directly to the HTTP request building process.
The operational impact of CVE-2012-3696 extends beyond simple header injection as it enables sophisticated HTTP request splitting attacks that can bypass security controls and manipulate web application behavior. Attackers can exploit this vulnerability to inject malicious headers that may cause web servers to cache incorrect responses, manipulate session tokens, or redirect traffic to malicious endpoints. The vulnerability is particularly dangerous in environments where Safari is used as a primary browser and where web applications rely on proper HTTP header validation for security purposes. This flaw can be weaponized in various attack scenarios including man-in-the-middle attacks, where attackers can inject headers to manipulate response caching, or in session management attacks where the injected headers can be used to hijack user sessions. The vulnerability affects both client-side and server-side security mechanisms, as it can cause web applications to process malformed HTTP requests that contain injected headers, potentially leading to data exposure or unauthorized access.
Mitigation strategies for CVE-2012-3696 primarily involve updating Safari to version 6.0 or later where Apple has implemented proper URI sanitization for WebSocket connections. Organizations should ensure all Safari installations are updated to the latest version that includes the patched WebKit engine with proper CRLF character filtering in URI parsing. Network administrators should implement web application firewalls that can detect and block suspicious HTTP header sequences, particularly those containing embedded CRLF characters in URI components. Additionally, security teams should monitor for potential exploitation attempts by analyzing HTTP traffic patterns for unusual header injection behaviors. The vulnerability aligns with CWE-113, which addresses improper neutralization of CRLF characters in HTTP headers, and maps to ATT&CK technique T1190 for exploiting vulnerabilities in web applications. Organizations should also implement regular security assessments of their web applications to ensure proper input validation and header sanitization, as this vulnerability demonstrates the importance of validating all user-supplied URI components before processing them in HTTP contexts.