CVE-2011-3246 in iOS
Summary
by MITRE
CFNetwork in Apple iOS before 5.0.1 and Mac OS X 10.7 before 10.7.2 does not properly parse URLs, which allows remote attackers to trigger visits to unintended web sites, and transmission of cookies to unintended web sites, via a crafted (1) http or (2) https URL.
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Analysis
by VulDB Data Team • 03/19/2021
The vulnerability identified as CVE-2011-3246 represents a critical URL parsing flaw within Apple's CFNetwork framework that affected iOS versions prior to 5.0.1 and Mac OS X 10.7.2. This vulnerability resides in the core networking infrastructure that handles HTTP and HTTPS protocol communications, making it a fundamental security weakness that could be exploited across numerous applications and services. The flaw specifically manifests in how the CFNetwork component processes and interprets Uniform Resource Locators, creating opportunities for malicious actors to manipulate network traffic and potentially compromise user data.
The technical implementation of this vulnerability stems from inadequate validation and parsing mechanisms within the URL handling code. When CFNetwork encounters malformed or specially crafted URLs, it fails to properly sanitize or validate the input before establishing network connections. This parsing deficiency allows attackers to construct URLs that appear legitimate to the user interface but contain hidden malicious elements that cause the system to redirect to unintended destinations or transmit session cookies to unauthorized servers. The vulnerability operates at the protocol level rather than the application level, making it particularly dangerous as it affects all applications that rely on CFNetwork for internet connectivity, including web browsers, email clients, and third-party applications.
The operational impact of this vulnerability extends beyond simple redirection attacks, as it creates opportunities for sophisticated man-in-the-middle attacks and session hijacking scenarios. Attackers can exploit this flaw to perform cookie theft by crafting URLs that cause the system to transmit authentication tokens to malicious servers, effectively allowing unauthorized access to user accounts on legitimate websites. Additionally, the vulnerability enables phishing attacks where users are unknowingly redirected to malicious sites that appear to be legitimate, as the system's URL parsing fails to properly identify and warn against suspicious redirection patterns. This issue particularly affects web applications that rely heavily on session management and authentication mechanisms, as the vulnerability can bypass security controls designed to protect against cross-site request forgery and similar attacks.
The exploitability of this vulnerability aligns with several ATT&CK framework techniques including T1566 for credential access through social engineering and T1071 for application layer protocol usage. From a CWE perspective, this vulnerability maps to CWE-129, which describes improper validation of input, and CWE-20, which covers input validation issues. The flaw demonstrates how insufficient bounds checking and validation in core networking components can create widespread security implications across an entire operating system. Organizations affected by this vulnerability must understand that the impact extends beyond individual applications to the fundamental network security posture of their systems. The vulnerability's persistence across multiple Apple platforms indicates a systemic issue within the CFNetwork implementation that required comprehensive patching and system updates to resolve.
Mitigation strategies for CVE-2011-3246 primarily focus on immediate system updates and network monitoring. Apple's release of iOS 5.0.1 and Mac OS X 10.7.2 contained the necessary patches to address the URL parsing deficiencies. Organizations should implement network traffic monitoring to detect unusual URL patterns and potential redirection attempts that may indicate exploitation attempts. Security teams should also consider implementing additional URL validation measures at network boundaries and application levels to provide defense in depth. The vulnerability underscores the importance of maintaining up-to-date security patches and the critical nature of core system components in maintaining overall security posture. Regular security assessments and vulnerability scanning should include verification of system components that handle URL processing and network communications to prevent similar issues from affecting organizational infrastructure.