CVE-2011-0216 in Safari
Summary
by MITRE
Off-by-one error in libxml in Apple Safari before 5.0.6 allows remote attackers to execute arbitrary code or cause a denial of service (heap-based buffer overflow and application crash) via a crafted web site.
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Analysis
by VulDB Data Team • 11/15/2021
The vulnerability identified as CVE-2011-0216 represents a critical heap-based buffer overflow flaw within Apple Safari's libxml library implementation prior to version 5.0.6. This off-by-one error occurs during the processing of malformed XML content, creating a condition where memory allocation calculations are incorrect, leading to memory corruption that can be exploited by remote attackers. The vulnerability specifically affects the XML parsing functionality that Safari uses to render web content, making it particularly dangerous as it can be triggered through standard web browsing activities.
The technical implementation of this vulnerability stems from improper bounds checking within the libxml library's memory management routines. When Safari processes XML data containing specially crafted malicious payloads, the off-by-one error causes the application to allocate insufficient memory for buffer operations, resulting in heap corruption that can be leveraged to execute arbitrary code or induce application crashes. This flaw aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The vulnerability operates at the intersection of memory safety issues and web browser security, making it particularly challenging to mitigate since it can be triggered through legitimate web content.
The operational impact of CVE-2011-0216 extends beyond simple denial of service scenarios to encompass full remote code execution capabilities, presenting significant risks to user systems. Attackers can craft malicious web pages that, when loaded in affected Safari versions, automatically trigger the buffer overflow condition without requiring user interaction beyond visiting the compromised site. This makes the vulnerability particularly dangerous in phishing campaigns or when exploited through compromised websites, as users can be exploited simply by browsing to malicious content. The vulnerability's exploitation can lead to complete system compromise, data theft, or persistent backdoor installation, making it a high-priority threat for organizations and individual users alike.
Mitigation strategies for CVE-2011-0216 primarily focus on immediate patching of affected Safari versions to 5.0.6 or later, which contains the necessary fixes for the libxml buffer overflow conditions. Organizations should implement comprehensive browser update policies and consider deploying automated patch management solutions to ensure rapid deployment of security fixes. Additionally, network-level protections such as web application firewalls and content filtering systems can provide additional defense-in-depth measures by blocking known malicious XML content patterns. From a threat modeling perspective, this vulnerability maps to ATT&CK technique T1203, which covers exploitation of software vulnerabilities through web-based attacks, and demonstrates the importance of maintaining up-to-date security patches across all browser components. System administrators should also consider implementing browser hardening measures and monitoring for suspicious network traffic patterns that might indicate exploitation attempts.