CVE-2011-3903 in Chrome
Summary
by MITRE
Google Chrome before 16.0.912.63 does not properly perform regex matching, which allows remote attackers to cause a denial of service (out-of-bounds read) via unspecified vectors.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 03/19/2021
The vulnerability identified as CVE-2011-3903 represents a critical flaw in Google Chrome's regular expression engine that existed prior to version 16.0.912.63. This issue stems from improper handling of regular expression matching operations within the browser's core rendering and scripting components. The flaw manifests as an out-of-bounds read condition that can be triggered through maliciously crafted regular expressions in web content, potentially leading to system instability and denial of service scenarios. The vulnerability's impact extends beyond simple browser crashes as it can be exploited to disrupt normal browser operations and potentially provide a foothold for more sophisticated attacks.
The technical implementation of this vulnerability resides in Chrome's JavaScript engine and regular expression processing modules. When the browser encounters malformed or specially crafted regular expressions, the regex engine fails to properly validate input boundaries during pattern matching operations. This improper boundary checking leads to memory access violations where the engine attempts to read data beyond the allocated memory boundaries of the regex pattern buffers. The flaw operates at the intersection of software security and memory management, where insufficient input validation allows attackers to manipulate the regex engine's internal state through carefully constructed malicious inputs.
From an operational perspective, this vulnerability creates significant risks for users who browse the internet without up-to-date security patches. Attackers can exploit this flaw by hosting malicious web pages containing crafted regular expressions that trigger the out-of-bounds read condition when Chrome processes the content. The denial of service impact can range from simple browser tab crashes to complete browser process termination, effectively disrupting user productivity and potentially providing cover for more advanced attacks. The vulnerability's remote exploitability means that users do not need to interact with malicious content directly for the attack to succeed, as simply visiting a compromised website can trigger the exploit.
The attack surface for CVE-2011-3903 aligns with several ATT&CK framework techniques including T1059.007 for script-based execution and T1499.004 for network denial of service. This vulnerability demonstrates the importance of proper input validation and memory safety in browser security architectures, as it represents a classic example of how improper boundary checking in core libraries can lead to exploitable conditions. The flaw also corresponds to CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds writes, both of which are common in memory safety issues within complex software systems. Organizations should prioritize patching this vulnerability immediately, as it represents a significant risk to browser security and can serve as a vector for more sophisticated exploitation techniques.
Mitigation strategies for this vulnerability require immediate deployment of Chrome updates to version 16.0.912.63 or later, which contain the necessary fixes for the regex engine's boundary checking mechanisms. System administrators should implement automated update mechanisms to ensure all browser instances remain current with security patches. Additionally, organizations should consider implementing network-based protections such as web application firewalls and content filtering systems that can detect and block known malicious regular expression patterns. Regular security assessments should include verification of browser versions and patch status to prevent exploitation of this and similar vulnerabilities. The remediation process should also involve user education about the importance of keeping browser software up-to-date and avoiding untrusted websites that may host malicious content designed to exploit such flaws.