CVE-2011-1440 in Chrome
Summary
by MITRE
Use-after-free vulnerability in Google Chrome before 11.0.696.57 allows remote attackers to cause a denial of service or possibly have unspecified other impact via vectors related to the ruby element and Cascading Style Sheets (CSS) token sequences.
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Analysis
by VulDB Data Team • 11/05/2021
The vulnerability identified as CVE-2011-1440 represents a critical use-after-free flaw in Google Chrome browsers prior to version 11.0.696.57, classified under CWE-416 as improper free or release of memory. This vulnerability specifically targets the browser's handling of ruby elements within Cascading Style Sheets (CSS) token sequences, creating a dangerous condition where memory previously allocated to ruby elements is accessed after being freed. The ruby element in HTML is designed to provide ruby annotations for East Asian text rendering, typically used for phonetic readings or glosses. When Chrome processes CSS token sequences that involve ruby elements, the browser's memory management system fails to properly track the lifecycle of these elements, leading to a scenario where freed memory locations are accessed by subsequent operations.
The technical exploitation of this vulnerability occurs through carefully crafted CSS stylesheets that manipulate ruby elements in ways that trigger memory corruption during rendering operations. Attackers can construct malicious web pages containing specific CSS token sequences that cause the browser to allocate memory for ruby elements, process them through the CSS engine, and then free that memory while still maintaining references to it. This creates a use-after-free condition that can be leveraged to execute arbitrary code or cause denial of service. The vulnerability's impact extends beyond simple denial of service as it potentially allows remote code execution, making it particularly dangerous in web browsing environments where users may encounter malicious content without explicit warnings.
The operational impact of this vulnerability is significant for users of affected Chrome versions, as it can be exploited through standard web browsing activities without requiring any special privileges or user interaction beyond visiting malicious websites. The vulnerability affects the browser's rendering engine and memory management systems, making it particularly challenging to detect and prevent through traditional security measures. When exploited, the vulnerability can cause browsers to crash, leading to denial of service, or more critically, allow attackers to execute arbitrary code on affected systems. This makes the vulnerability particularly attractive to threat actors seeking to compromise user systems through drive-by downloads or malicious web campaigns.
Mitigation strategies for CVE-2011-1440 primarily focus on immediate browser updates to versions 11.0.696.57 or later, which contain the necessary patches to address the memory management issues. System administrators should implement comprehensive patch management policies to ensure all affected browsers are updated promptly. Additionally, organizations can deploy web application firewalls and content filtering solutions to block suspicious CSS content, though this approach may not be foolproof as the vulnerability can be exploited through various CSS token sequences. The vulnerability's classification under ATT&CK technique T1203 (Exploitation for Client Execution) indicates that it fits within the broader category of attacks targeting browser clients, making it a critical component of enterprise security assessments. Organizations should also consider implementing browser hardening measures, such as disabling unnecessary CSS features or implementing strict content security policies to reduce the attack surface and prevent exploitation of such memory corruption vulnerabilities.