CVE-2009-1690 in Safari
Summary
by MITRE
Use-after-free vulnerability in WebKit, as used in Apple Safari before 4.0, iPhone OS 1.0 through 2.2.1, iPhone OS for iPod touch 1.1 through 2.2.1, Google Chrome 1.0.154.53, and possibly other products, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) by setting an unspecified property of an HTML tag that causes child elements to be freed and later accessed when an HTML error occurs, related to "recursion in certain DOM event handlers."
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Analysis
by VulDB Data Team • 08/11/2021
The vulnerability described in CVE-2009-1690 represents a critical use-after-free condition within the WebKit rendering engine that affected multiple high-profile web browsers and operating systems. This flaw existed in Apple Safari versions prior to 4.0 and various iPhone OS versions through 2.2.1, as well as in Google Chrome 1.0.154.53, demonstrating the widespread impact of WebKit-based vulnerabilities across different platforms. The issue stems from improper memory management during DOM (Document Object Model) operations, specifically when handling certain HTML elements and their associated event handlers.
The technical flaw manifests when an HTML tag with an unspecified property is manipulated in a way that causes child elements to be freed from memory while simultaneously being scheduled for later access during error handling scenarios. This creates a race condition where memory that has been deallocated is subsequently accessed, leading to unpredictable behavior. The vulnerability is particularly dangerous because it involves recursion within certain DOM event handlers, meaning that the memory corruption can occur through nested event processing that is common in web applications. This recursive pattern amplifies the attack surface and makes the exploitation more reliable.
The operational impact of this vulnerability extends beyond simple application crashes to potentially enable remote code execution, making it a severe security concern for users. When an attacker crafts malicious HTML content that triggers this specific sequence of DOM operations, the memory corruption can be leveraged to execute arbitrary code on the target system. This capability transforms what might initially appear as a denial of service vulnerability into a full remote exploitation vector. The memory corruption can be triggered through various means including crafted web pages, malicious advertisements, or compromised websites, making it particularly dangerous in real-world scenarios where users encounter untrusted content.
From a cybersecurity perspective, this vulnerability aligns with CWE-416, which describes the use of freed memory condition, and represents a classic example of how improper memory management can lead to critical security flaws. The ATT&CK framework would categorize this under T1059 for command and scripting interpreter and potentially T1203 for Exploitation for Client Execution, as the vulnerability enables remote code execution through web-based attacks. Organizations affected by this vulnerability needed to implement immediate mitigations including browser updates, content filtering, and user education about avoiding untrusted web content. The incident highlighted the importance of regular security updates and proper memory management practices in browser development, particularly in complex rendering engines that handle extensive DOM manipulation and event handling scenarios.