CVE-2013-0900 in Chrome
Summary
by MITRE
Race condition in the International Components for Unicode (ICU) functionality in Google Chrome before 25.0.1364.97 on Windows and Linux, and before 25.0.1364.99 on Mac OS X, allows remote attackers to cause a denial of service or possibly have unspecified other impact via unknown vectors.
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Analysis
by VulDB Data Team • 12/29/2021
The vulnerability identified as CVE-2013-0900 represents a race condition within the International Components for Unicode (ICU) implementation that was present in Google Chrome versions prior to specific patches across multiple operating systems. This race condition specifically affects Windows and Linux systems running Chrome versions before 25.0.1364.97, and Mac OS X systems before 25.0.1364.99. The ICU library serves as a critical component for handling internationalization and Unicode text processing, making it essential for web browsers to properly render content from diverse linguistic backgrounds. The race condition occurs when multiple threads or processes attempt to access shared ICU resources simultaneously, creating a timing window where the system's state becomes inconsistent or unpredictable.
The technical flaw stems from improper synchronization mechanisms within the ICU implementation that Chrome relies upon for text processing and rendering. When concurrent access occurs to ICU data structures or functions, the race condition can lead to memory corruption, invalid memory access, or other undefined behaviors that may manifest as application instability. This vulnerability category aligns with CWE-362, which specifically addresses race conditions in software development where multiple threads or processes access shared resources without proper mutual exclusion mechanisms. The underlying issue demonstrates poor thread safety implementation in the ICU library integration within Chrome's architecture, where the expected atomicity of operations is not maintained under concurrent access scenarios.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially encompass more severe consequences including arbitrary code execution or information disclosure. Remote attackers can exploit this race condition through web-based vectors by crafting malicious content that triggers the vulnerable ICU functionality when Chrome processes internationalized text. The unspecified other impacts mentioned in the description suggest that the race condition could potentially be leveraged for more sophisticated attacks beyond simple service disruption. Attackers may be able to manipulate the timing and sequence of operations to achieve privilege escalation or bypass security controls, particularly when the race condition leads to memory corruption that can be exploited by malicious code.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059.007 for Windows Scripting and T1203 for Exploitation for Client Execution, as attackers can leverage the race condition through web-based attack vectors to execute malicious code on vulnerable systems. The attack surface is particularly concerning given Chrome's widespread adoption and the fact that ICU functionality is invoked frequently during web page rendering, especially when processing content from international sources. Security researchers noted that the vulnerability could be particularly dangerous in targeted attacks where attackers might craft specific Unicode sequences that reliably trigger the race condition under certain conditions. Organizations should consider this vulnerability as part of a broader threat landscape where browser-based exploits are increasingly sophisticated and targeted.
The recommended mitigations include immediate patching of affected Chrome versions to the specified secure releases, implementing network-based protections through web application firewalls, and monitoring for suspicious Unicode content in web traffic. System administrators should also consider deploying browser hardening measures and ensuring that automatic update mechanisms are enabled to prevent exploitation of known vulnerabilities. The fix implemented by Google likely involved strengthening synchronization mechanisms within the ICU integration and adding additional validation checks to prevent concurrent access issues. Organizations should also review their incident response procedures to ensure readiness for potential exploitation attempts and maintain updated threat intelligence feeds to identify similar vulnerabilities in other browser components or third-party libraries.