CVE-2012-5836 in Firefox
Summary
by MITRE
Mozilla Firefox before 17.0, Thunderbird before 17.0, and SeaMonkey before 2.14 allow remote attackers to execute arbitrary code or cause a denial of service (application crash) via vectors involving the setting of Cascading Style Sheets (CSS) properties in conjunction with SVG text.
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Analysis
by VulDB Data Team • 12/29/2024
This vulnerability exists in Mozilla Firefox versions prior to 17.0, Thunderbird versions prior to 17.0, and SeaMonkey versions prior to 2.14, representing a critical security flaw that allows remote attackers to execute arbitrary code or cause denial of service through specific combinations of Cascading Style Sheets CSS properties and SVG text elements. The vulnerability stems from improper handling of CSS properties when applied to Scalable Vector Graphics text elements, creating a condition where maliciously crafted web content can trigger unexpected behavior in the browser rendering engine. The technical flaw manifests when the browser processes CSS rules that interact with SVG text nodes, leading to memory corruption or unexpected execution paths that can be exploited by attackers.
The operational impact of this vulnerability is significant as it enables remote code execution attacks that can compromise user systems without requiring any user interaction beyond visiting a malicious website. Attackers can craft web pages containing specially designed CSS rules that, when rendered by the vulnerable browsers, cause the application to crash or potentially execute arbitrary code with the privileges of the user running the browser. This represents a classic use-after-free vulnerability pattern where memory allocated to SVG text elements becomes corrupted when CSS properties are applied in specific sequences. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-119, which covers weak buffer access in memory management, both of which are commonly exploited in browser-based attacks.
The exploitation of this vulnerability can be categorized under the ATT&CK framework as a web-based attack vector that leverages browser rendering engine flaws to achieve code execution. Security researchers have documented that the vulnerability typically involves crafting malicious SVG elements with CSS properties that trigger memory corruption during the rendering process. The attack surface is particularly concerning because it affects multiple Mozilla products, increasing the potential impact across different user environments. Organizations should prioritize patching all affected versions to prevent exploitation, as the vulnerability can be easily weaponized through standard web delivery methods. The fix implemented by Mozilla involved strengthening input validation for CSS properties applied to SVG elements and improving memory management during rendering operations.
This vulnerability demonstrates the ongoing challenges in browser security where complex rendering engines like those used in Firefox and Thunderbird can contain subtle flaws that become exploitable through sophisticated attack vectors. The combination of CSS and SVG elements creates a particularly dangerous attack surface because both technologies are commonly used in web content, making the vulnerability difficult to detect and prevent through traditional security measures. The remediation requires immediate updates to all affected Mozilla products, with organizations implementing security awareness training to help prevent users from visiting malicious websites that could exploit this flaw. System administrators should also consider implementing network-level protections and monitoring for suspicious web traffic patterns that might indicate attempts to exploit this vulnerability.