CVE-2005-4718 in Web Browser
Summary
by MITRE
Opera 8.02 and earlier allows remote attackers to cause a denial of service (client crash) via (1) a crafted HTML file with a "content: url(0);" style attribute, a "bodyA" tag, a long string, and a "u" tag with a long attribute, as demonstrated by opera.html; and (2) a BGSOUND element with a "margin:-99;" STYLE attribute.
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Analysis
by VulDB Data Team • 01/23/2025
This vulnerability affects Opera web browser versions 8.02 and earlier, presenting a significant denial of service risk that can be exploited remotely by malicious actors. The flaw manifests through specifically crafted HTML content that triggers client-side crashes, effectively disrupting normal browser operations and potentially compromising user experience. The vulnerability demonstrates how seemingly innocuous HTML elements can be manipulated to create destructive outcomes when processed by older browser rendering engines.
The technical implementation of this vulnerability involves two distinct attack vectors that exploit memory management issues within Opera's HTML parser and rendering engine. The first vector utilizes a combination of CSS style attributes including "content: url(0);" within a "bodyA" tag structure, augmented with a long string and a "u" tag containing an extended attribute. This specific combination creates memory allocation patterns that cause buffer overflows or memory corruption within the browser's processing pipeline. The second vector employs the BGSOUND element with a "margin:-99;" STYLE attribute, which similarly manipulates CSS parsing routines to trigger similar memory-related failures. Both attack methods leverage the browser's failure to properly validate and sanitize input parameters before processing them.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable more sophisticated attack scenarios. When exploited, these crafted HTML files can cause complete browser crashes, forcing users to restart their browsing sessions and potentially lose unsaved work. The vulnerability affects any user who encounters these maliciously crafted web pages, making it particularly dangerous in environments where users may inadvertently visit compromised websites or receive malicious email attachments containing such HTML content. The remote nature of the attack means that threat actors can exploit this vulnerability without requiring physical access to target systems, making it a particularly concerning security flaw.
From a cybersecurity perspective, this vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The attack patterns demonstrate characteristics consistent with the attacker tactics described in the MITRE ATT&CK framework under the T1203 technique for "Exploitation for Client Execution," where adversaries leverage application vulnerabilities to execute malicious code or cause system instability. The vulnerability also relates to T1499, which covers "Endpoint Denial of Service" and represents a classic example of how improper input validation can lead to system instability.
Effective mitigation strategies for this vulnerability require immediate browser updates to versions that address the specific parsing flaws. Organizations should implement comprehensive patch management protocols to ensure all Opera installations are updated promptly. Additionally, network administrators should consider implementing web filtering solutions that can detect and block known malicious HTML patterns. User education regarding the dangers of visiting untrusted websites and opening suspicious email attachments remains crucial. Browser security enhancements such as sandboxing and strict content validation should be enabled to provide additional layers of protection against similar vulnerabilities. The vulnerability underscores the importance of regular security assessments and continuous monitoring of browser security updates to prevent exploitation of known flaws.