CVE-2012-3564 in Web Browser
Summary
by MITRE
Opera before 12.00 Beta allows remote attackers to cause a denial of service (application hang) via an absolutely positioned wrap=off TEXTAREA element located next to an "overflow: auto" block element.
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Analysis
by VulDB Data Team • 01/17/2018
The vulnerability identified as CVE-2012-3564 represents a denial of service flaw affecting Opera web browsers prior to version 12.00 Beta. This issue manifests when specific HTML elements are rendered in a particular combination that triggers application instability. The flaw occurs within the browser's rendering engine when processing certain CSS positioning and overflow properties in conjunction with textarea elements, creating a scenario where the application becomes unresponsive and hangs during page rendering.
The technical root cause of this vulnerability lies in how Opera's browser engine handles the interaction between absolutely positioned elements with wrap=off attributes and block elements that have overflow: auto styling. When these specific HTML constructs are parsed and rendered together, the browser's layout calculation algorithm enters an infinite loop or encounters a condition that causes it to consume excessive CPU resources while attempting to determine element positioning and text wrapping behavior. This represents a classic case of improper input validation and resource management within the browser's rendering pipeline.
From an operational impact perspective, this vulnerability enables remote attackers to execute denial of service attacks against Opera users by simply crafting malicious web pages containing the specific element combinations. The attack requires no special privileges or user interaction beyond visiting the malicious webpage, making it particularly dangerous in web browsing environments where users may encounter untrusted content. The application hang that results from this flaw effectively renders the browser unusable until manually terminated, disrupting user productivity and potentially creating security concerns if users are unable to access security updates or other critical browser functions.
The vulnerability aligns with CWE-400, which categorizes improper handling of input validation and resource management in web browsers, and demonstrates characteristics consistent with the ATT&CK technique T1499.004 for network denial of service attacks. This flaw specifically targets the browser's rendering engine rather than the underlying operating system, making it a client-side attack vector that exploits the browser's HTML parsing and CSS rendering capabilities. The issue affects not only individual users but also organizations that rely on Opera as their primary browser, potentially creating widespread service disruption if exploited at scale.
Mitigation strategies for this vulnerability primarily involve updating to Opera version 12.00 Beta or later, which includes fixes for the rendering engine's handling of these specific element combinations. Users should also implement browser security best practices including keeping software updated, using security extensions, and avoiding untrusted websites. Organizations should consider implementing web content filtering solutions and network-based protections to prevent exposure to malicious content. Additionally, web developers should be aware of this vulnerability when creating HTML content and avoid using problematic element combinations that could trigger browser instability. The fix implemented in Opera 12.00 Beta likely involved improvements to the browser's layout engine's handling of CSS positioning calculations and text wrapping algorithms to prevent the infinite loop condition that previously occurred.