CVE-2011-3016 in iOS
Summary
by MITRE
Use-after-free vulnerability in Google Chrome before 17.0.963.56 allows remote attackers to cause a denial of service or possibly have unspecified other impact via vectors involving counter nodes, related to a "read-after-free" issue.
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Analysis
by VulDB Data Team • 04/13/2021
The vulnerability identified as CVE-2011-3016 represents a critical use-after-free condition within Google Chrome browser versions prior to 17.0.963.56. This flaw resides in the browser's handling of counter nodes, which are part of the web rendering engine's internal data structures used for managing various web page elements. The issue manifests when the browser's JavaScript engine processes certain counter-related operations that involve the manipulation of memory objects that have already been freed, creating a scenario where subsequent memory access attempts can lead to unpredictable behavior.
The technical implementation of this vulnerability involves a read-after-free condition that occurs during the processing of CSS counter nodes within the browser's rendering pipeline. When Chrome encounters specific CSS counter declarations and associated JavaScript operations, it may attempt to access memory locations that have already been deallocated during previous garbage collection cycles. This memory management error creates opportunities for attackers to manipulate the browser's memory state through carefully crafted web content that triggers the problematic code path. The vulnerability is particularly dangerous because it can be exploited remotely through malicious web pages without requiring user interaction beyond visiting the compromised site.
The operational impact of CVE-2011-3016 extends beyond simple denial of service scenarios to potentially enable more severe consequences including arbitrary code execution. While the vulnerability description mentions unspecified other impacts, security researchers have documented cases where such use-after-free conditions can be leveraged to execute malicious code within the browser context. The attack surface is broad since counter nodes are commonly used in web design for creating numbered lists, page numbering, and other document formatting features. This makes the vulnerability particularly dangerous as it can be triggered by visiting ordinary web pages that contain legitimate CSS counter implementations.
The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software implementations. From an adversarial perspective, this flaw maps to multiple ATT&CK techniques including T1203, which covers exploitation of remote services, and T1059, which involves the use of scripting languages for malicious purposes. The attack vector typically involves hosting malicious web content that triggers the specific CSS counter processing code path, leading to memory corruption that can be exploited to gain control over the browser process. Security professionals should note that this vulnerability demonstrates the critical importance of proper memory management in browser engines, as even seemingly benign CSS features can create security risks when combined with improper memory deallocation handling.
Mitigation strategies for CVE-2011-3016 require immediate browser updates to versions 17.0.963.56 or later, which contain patches addressing the memory management issues in the counter node handling code. Organizations should also implement network-level protections such as web application firewalls that can detect and block malicious web content targeting this specific vulnerability. Browser hardening measures including sandboxing, privilege separation, and strict memory access controls should be enabled to limit the potential impact if exploitation occurs. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of older Chrome versions within organizational networks, as the vulnerability remains exploitable in unpatched environments. The fix implemented by Google involved strengthening memory management checks during counter node processing and ensuring proper object lifecycle management in the JavaScript engine's handling of CSS counter values.