CVE-2004-1613 in Mozilla
Summary
by MITRE
Mozilla allows remote attackers to cause a denial of service (application crash from null dereference or infinite loop) via a web page that contains a (1) TEXTAREA, (2) INPUT, (3) FRAMESET or (4) IMG tag followed by a null character and some trailing characters, as demonstrated by mangleme.
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Analysis
by VulDB Data Team • 05/31/2019
This vulnerability exists in the Mozilla browser implementation where improper handling of certain HTML tags followed by null characters can lead to application instability. The flaw specifically affects TEXTAREA, INPUT, FRAMESET, and IMG HTML elements when they are immediately followed by a null character and additional trailing data. The vulnerability stems from the browser's HTML parsing logic failing to properly validate or sanitize input sequences containing these specific tag patterns combined with null byte terminators. When the browser encounters such malformed HTML structures during page rendering, the parsing engine enters an undefined state that results in either a null pointer dereference or an infinite loop execution path, ultimately causing the application to crash and terminate unexpectedly.
The technical nature of this vulnerability aligns with CWE-476 which describes null pointer dereference conditions in software implementations. The attack vector involves remote exploitation through malicious web content that triggers the parsing error when the browser attempts to render the malformed HTML. This represents a classic denial of service vulnerability where an attacker can craft specific HTML pages that will cause the target browser to become unresponsive or terminate entirely. The vulnerability is particularly concerning because it can be exploited through standard web browsing activities without requiring any special privileges or user interaction beyond visiting the malicious webpage. The mangleme demonstration proves that even simple modifications to standard HTML tag structures can create conditions that overwhelm the browser's parsing engine.
The operational impact of this vulnerability extends beyond simple service disruption as it can be used as part of larger attack chains. When an attacker successfully exploits this vulnerability, they can effectively deny service to legitimate users of the affected browser by causing it to crash repeatedly. This makes the vulnerability particularly dangerous in environments where browser stability is critical for business operations or where users might encounter malicious content through phishing campaigns or compromised websites. The infinite loop condition can also consume significant system resources, potentially leading to system-wide performance degradation or even system crashes if the resource exhaustion is severe enough. From an attacker's perspective, this vulnerability requires minimal skill to exploit and can be easily automated, making it a preferred target for mass deployment attacks.
Mitigation strategies for this vulnerability should focus on implementing robust input validation and sanitization within the browser's HTML parsing engine. Browser vendors should ensure that all HTML tag processing routines include proper null character handling and bounds checking before attempting to process tag data. The fix should involve modifying the parser to either ignore or properly handle null characters within HTML tag structures, preventing the execution paths that lead to null pointer dereferences or infinite loops. Additionally, implementing defensive programming practices such as input length limits and character validation can prevent malformed sequences from reaching the core parsing logic. Organizations should also consider implementing web application firewalls or content filtering systems that can detect and block known malicious HTML patterns, while keeping browsers updated with the latest security patches. This vulnerability highlights the importance of thorough input validation in web browser implementations and demonstrates how seemingly minor parsing edge cases can have significant security implications. The ATT&CK framework would categorize this as a Denial of Service attack technique where the adversary leverages application vulnerabilities to disrupt service availability for legitimate users.