CVE-2016-1789 in iBooks Author
Summary
by MITRE
Apple iBooks Author before 2.4.1 allows remote attackers to read arbitrary files via an iBooks Author file containing an XML external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
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Analysis
by VulDB Data Team • 10/11/2024
The vulnerability identified as CVE-2016-1789 represents a critical XML External Entity (XXE) flaw in Apple iBooks Author versions prior to 2.4.1. This issue stems from the application's insufficient input validation when processing iBooks Author files that contain XML external entity declarations. The vulnerability manifests when an attacker crafts a malicious iBooks Author file containing an XML external entity declaration followed by an entity reference, enabling unauthorized file access on the target system. The flaw operates at the XML parser level where the application fails to properly sanitize external entity references during file processing, creating a pathway for attackers to access arbitrary files on the host machine. This vulnerability aligns with CWE-611, which categorizes improper restriction of XML external entities, and represents a classic XXE attack vector that has been widely documented in cybersecurity literature.
The technical exploitation of this vulnerability requires an attacker to create a specially crafted iBooks Author file containing malicious XML content that references external entities. When the vulnerable iBooks Author application processes this file, it attempts to resolve the external entity references, potentially allowing access to local files that should remain protected. The attack can be extended to access system resources, configuration files, or sensitive data stored on the local filesystem. This XXE implementation leverages the standard XML parsing behavior where external entities are resolved without proper validation, enabling attackers to perform information disclosure attacks. The vulnerability essentially bypasses normal file access controls by utilizing the XML parser's built-in capability to resolve external references, which is typically intended for legitimate network resources but becomes exploitable when malicious entities are introduced.
The operational impact of CVE-2016-1789 extends beyond simple information disclosure to potentially enable more sophisticated attacks within the context of Apple's ecosystem. An attacker who successfully exploits this vulnerability could gain access to sensitive user data, application configuration files, or system information that might aid in further exploitation. The vulnerability affects users who open potentially malicious iBooks Author files, making it particularly concerning in environments where users might encounter untrusted content. Given that iBooks Author is commonly used for creating educational and professional content, the attack surface includes educational institutions, corporate environments, and individual users who might inadvertently open compromised files. This vulnerability also intersects with ATT&CK technique T1059.007, which covers XML External Entity Processing, and demonstrates how desktop applications can become attack vectors when they fail to properly validate XML inputs.
Mitigation strategies for CVE-2016-1789 primarily involve updating to Apple iBooks Author version 2.4.1 or later, which includes proper XML parsing safeguards that prevent external entity resolution. System administrators should implement strict file validation policies and consider sandboxing mechanisms for processing iBooks Author files. Organizations should also deploy network monitoring solutions to detect potential XXE attack patterns and ensure that users receive security awareness training about opening untrusted files. The vulnerability highlights the importance of proper XML parser configuration and input validation in desktop applications, particularly those that process user-generated content. Security professionals should also consider implementing application whitelisting policies that restrict the execution of potentially vulnerable applications and ensure that all software components are kept up to date with the latest security patches. The remediation process requires not only updating the vulnerable application but also reviewing other XML processing components within the organization's software stack to identify similar XXE vulnerabilities.