CVE-2019-8749 in iTunes
Summary
by MITRE • 10/28/2020
Multiple memory corruption issues were addressed with improved input validation. This issue is fixed in macOS Catalina 10.15, iOS 13, iCloud for Windows 7.14, iCloud for Windows 10.7, tvOS 13, macOS Catalina 10.15.1, Security Update 2019-001, and Security Update 2019-006, watchOS 6, iTunes 12.10.1 for Windows. Multiple issues in libxml2.
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Analysis
by VulDB Data Team • 11/28/2020
The vulnerability identified as CVE-2019-8749 represents a critical class of memory corruption issues affecting the libxml2 library implementation across multiple Apple operating systems and applications. This vulnerability stems from inadequate input validation mechanisms within the XML parsing functionality that processes malformed or maliciously crafted XML data streams. The affected components include core system libraries and applications that rely on libxml2 for XML processing, creating widespread potential impact across Apple's ecosystem. The memory corruption issues arise from improper handling of edge cases during XML document parsing, where insufficient bounds checking and memory allocation validation allows attackers to manipulate memory structures through carefully crafted inputs.
The technical flaw manifests as a result of CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. These vulnerabilities occur when the libxml2 library fails to properly validate input parameters during XML parsing operations, leading to memory corruption that can be exploited to execute arbitrary code or cause application crashes. The vulnerability affects both the structure and content validation phases of XML processing, where attackers can craft malicious XML documents that trigger memory allocation errors or overwrite adjacent memory regions. The implementation lacks proper bounds checking mechanisms that would normally prevent buffer overflows during parsing operations, particularly when handling large or malformed XML elements.
The operational impact of CVE-2019-8749 extends across multiple attack vectors and system components, making it particularly dangerous in enterprise and consumer environments. Attackers can leverage this vulnerability through various means including email attachments, web content, or file downloads that contain malicious XML data. The exploitation potential aligns with ATT&CK technique T1203, which describes exploitation of remote services, and T1059, covering command and scripting interpreters. Applications that process untrusted XML data such as web browsers, email clients, and document processing applications become vulnerable to remote code execution or denial of service conditions. The vulnerability's presence in both macOS and Windows versions of iCloud applications creates cross-platform exploitation opportunities, while the inclusion of tvOS and watchOS versions expands the attack surface to consumer electronics and IoT devices.
Mitigation strategies for CVE-2019-8749 should prioritize immediate deployment of available security updates from Apple, as these patches address the root causes through improved input validation and memory management. Organizations should implement network-based protections including XML filtering and content validation at perimeter defenses, utilizing security controls that can detect and block malicious XML content before it reaches vulnerable applications. The remediation process involves updating to patched versions including macOS Catalina 10.15, iOS 13, and respective security updates, while also implementing application whitelisting to restrict execution of untrusted XML processing components. System administrators should conduct comprehensive vulnerability assessments to identify all instances of libxml2 usage within their environments and ensure proper patch management protocols are in place. Additionally, monitoring for anomalous XML processing behavior and implementing intrusion detection systems can help identify exploitation attempts before successful compromise occurs.