CVE-2015-5835 in iOS
Summary
by MITRE
Apple iOS before 9 allows attackers to obtain sensitive information about inter-app communication via a crafted app that conducts an interception attack involving an unspecified URL scheme.
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Analysis
by VulDB Data Team • 06/16/2022
The vulnerability identified as CVE-2015-5835 represents a significant security flaw in Apple iOS versions prior to 9.0 that compromises the integrity of inter-app communication mechanisms through improper handling of URL schemes. This weakness enables malicious actors to conduct interception attacks by crafting specially designed applications that exploit the operating system's insufficient validation of URL scheme handlers. The vulnerability specifically targets the manner in which iOS processes and routes URL scheme requests between applications, creating opportunities for unauthorized information disclosure during legitimate inter-application interactions.
The technical implementation of this vulnerability stems from inadequate input validation within the iOS URL handling framework. When applications register URL schemes for inter-app communication, the operating system should properly verify the authenticity and legitimacy of incoming requests before forwarding them to target applications. However, iOS versions before 9.0 failed to adequately validate these URL scheme invocations, allowing attackers to manipulate the routing process through crafted malicious applications. This flaw operates at the system level where URL scheme handlers are invoked without sufficient security checks, potentially exposing sensitive data that would normally be protected by iOS security boundaries.
The operational impact of CVE-2015-5835 extends beyond simple information disclosure to potentially enable more sophisticated attacks within the iOS ecosystem. Attackers can leverage this vulnerability to intercept communications between legitimate applications, potentially accessing sensitive user data, session tokens, or other confidential information exchanged through URL scheme mechanisms. The vulnerability is particularly concerning because it operates at the system level and can be exploited through seemingly benign applications that appear legitimate to users. This creates a stealthy attack vector where malicious actors can monitor and potentially manipulate inter-app communications without user awareness, potentially leading to privilege escalation or data exfiltration scenarios.
From a security framework perspective, this vulnerability aligns with CWE-200, which addresses "Information Exposure," and represents a failure in proper access control mechanisms. The flaw also relates to ATT&CK technique T1056.001, which covers "Input Injection: Data Injection," as the attack involves injecting malicious data through URL scheme handlers. The vulnerability demonstrates poor defense-in-depth principles where multiple security layers should have prevented unauthorized access to inter-app communication channels. Organizations and users affected by this vulnerability should prioritize updating to iOS 9.0 or later, which implements proper URL scheme validation and improved inter-app communication security controls. Additionally, security teams should conduct thorough assessments of applications that rely on URL schemes for inter-app communication and implement monitoring for suspicious URL scheme activity.
The remediation approach for this vulnerability requires comprehensive system updates to iOS 9.0 or higher, which addresses the core URL scheme handling issues through enhanced input validation and improved security boundaries between applications. Security professionals should also implement application whitelisting policies and monitor for unauthorized URL scheme registrations. The vulnerability highlights the importance of proper input validation in mobile operating systems and demonstrates how seemingly minor implementation flaws can create significant security risks in complex application ecosystems. Organizations should consider implementing additional monitoring controls to detect and prevent similar attacks targeting inter-app communication mechanisms in their mobile environments.