CVE-2016-1841 in iOS
Summary
by MITRE
libxslt, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site.
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Analysis
by VulDB Data Team • 08/21/2022
The vulnerability identified as CVE-2016-1841 represents a critical memory corruption flaw within the libxslt library implementation across multiple Apple operating systems. This issue affects iOS versions prior to 9.3.2, macOS versions before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, demonstrating the widespread impact of improper memory handling in XML processing components. The vulnerability stems from insufficient input validation and memory management within the XSLT transformation engine, which processes XML documents with styling rules. Attackers can exploit this weakness by crafting malicious websites that trigger specific XML processing scenarios, leading to unpredictable memory corruption patterns that can be leveraged for remote code execution or denial of service conditions.
The technical exploitation of this vulnerability occurs through improper handling of malformed XSLT transformations within web content processing. When the affected libxslt library processes specially crafted XML documents containing malicious XSLT instructions, memory corruption occurs due to inadequate bounds checking and memory allocation validation. This flaw falls under the CWE-125 vulnerability category, which describes out-of-bounds read conditions that can lead to memory corruption and arbitrary code execution. The vulnerability operates at the intersection of XML processing and memory management, where the library fails to properly validate transformation parameters and memory access patterns during document processing. The attack vector typically involves web-based exploitation where malicious content is delivered through compromised websites or maliciously crafted web pages that utilize XSLT processing capabilities.
The operational impact of CVE-2016-1841 extends beyond simple denial of service scenarios to encompass full remote code execution capabilities that can compromise entire user sessions. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the affected application, potentially leading to complete system compromise. The memory corruption patterns associated with this flaw can result in unpredictable behavior including application crashes, system instability, or more sinisterly, the execution of malicious payloads that persist across system sessions. Organizations running affected Apple operating systems face significant risk exposure, as the vulnerability can be exploited through standard web browsing activities without requiring any special privileges or user interaction beyond visiting malicious websites. The widespread adoption of these operating systems across enterprise and consumer environments amplifies the potential impact of this vulnerability.
Mitigation strategies for CVE-2016-1841 primarily focus on immediate patch deployment and system updates to address the underlying memory corruption issues within libxslt. Organizations should prioritize updating all affected Apple operating systems to their respective patched versions, which include memory safety improvements and enhanced input validation mechanisms. Network administrators should implement web filtering solutions and content security policies to block access to known malicious domains that may exploit this vulnerability. Additionally, security monitoring should include detection of unusual XML processing activities that might indicate exploitation attempts. The remediation process should also involve comprehensive vulnerability assessments to identify any custom applications or web services that might be utilizing vulnerable libxslt components. Security teams should consider implementing runtime protections and application whitelisting to prevent exploitation attempts. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for command and script interpreter execution, highlighting the potential for malicious code execution through web-based attack vectors that leverage the memory corruption for privilege escalation and persistent access.