CVE-2006-2019 in Safari
Summary
by MITRE
Apple Mac OS X Safari 2.0.3, 1.3.1, and possibly other versions allows remote attackers to cause a denial of service (CPU consumption and crash) via a TD element with a large number in the rowspan attribute.
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Analysis
by VulDB Data Team • 06/23/2024
The vulnerability described in CVE-2006-2019 represents a classic denial of service flaw affecting Apple Mac OS X Safari web browser versions 2.0.3 and 1.3.1, with potential impact on other versions within the same release series. This issue specifically targets the browser's HTML parsing engine when processing table elements, particularly the td element with excessive rowspan attributes. The vulnerability falls under the category of resource exhaustion attacks where maliciously crafted HTML content can trigger abnormal CPU consumption patterns leading to browser instability and eventual crashes. The flaw demonstrates how seemingly innocuous HTML attributes can be exploited to compromise system availability, highlighting the importance of robust input validation in web rendering engines.
The technical mechanism behind this vulnerability involves the browser's handling of table row spanning attributes within HTML documents. When Safari encounters a td element with an unusually large number in the rowspan attribute, the browser's rendering engine attempts to allocate memory and process the table structure in a manner that consumes excessive computational resources. This occurs because the browser's HTML parser does not properly validate or limit the values of rowspan attributes, allowing attackers to specify arbitrarily large numbers that force the rendering engine to perform intensive calculations and memory allocations. The vulnerability is classified as a CWE-129 weakness, specifically related to insufficient validation of the length or number of input data, which enables attackers to cause the system to consume excessive resources through malformed input.
From an operational perspective, this vulnerability presents significant risks to users browsing the internet, as it can be exploited through malicious websites or compromised web content without requiring any special privileges from the user. The attack vector is particularly dangerous because it can be delivered through standard web browsing activities, making it difficult for users to protect themselves against such attacks. The impact extends beyond simple browser crashes to include potential system performance degradation, as the excessive CPU consumption can affect overall system responsiveness and potentially impact other running applications. This type of vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and represents a form of resource exhaustion that can be used as part of broader attack campaigns targeting system availability.
The mitigation strategies for this vulnerability primarily involve updating to patched versions of Safari where the HTML parsing logic has been corrected to properly validate rowspan attribute values and implement reasonable limits on table structure complexity. Users should also employ security measures such as web content filtering and sandboxing technologies that can help contain the impact of such attacks. Browser vendors should implement more robust input validation mechanisms and consider implementing rate limiting or resource consumption monitoring to detect and prevent similar attacks. Additionally, security awareness training for users about the dangers of visiting untrusted websites and the importance of keeping software updated remains crucial in defending against such vulnerabilities that exploit rendering engine weaknesses.