CVE-2010-0181 in Firefox
Summary
by MITRE
Mozilla Firefox before 3.5.9 and 3.6.x before 3.6.2, and SeaMonkey before 2.0.4, executes a mail application in situations where an IMG element has a SRC attribute that is a redirect to a mailto: URL, which allows remote attackers to cause a denial of service (excessive application launches) via an HTML document with many images.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 09/07/2021
This vulnerability exists in Mozilla Firefox versions prior to 3.5.9 and 3.6.x versions prior to 3.6.2, as well as in SeaMonkey versions before 2.0.4. The flaw stems from the browser's improper handling of mailto: URLs within HTML image elements, specifically when these URLs are redirected through intermediate HTTP redirects. The vulnerability is classified under CWE-120 as a buffer overflow condition, though in this case it manifests as a denial of service rather than code execution. The issue occurs when a web page contains multiple IMG elements where each SRC attribute points to a URL that redirects to a mailto: address, creating an exploitable scenario for remote attackers to abuse the browser's mail application launch mechanism.
The technical exploitation involves constructing an HTML document containing numerous image elements with redirecting SRC attributes that ultimately resolve to mailto: URLs. When the browser processes such a document, it attempts to load each image, triggering the redirect chain that leads to mailto: URL resolution. The browser's handling of these redirects causes it to launch the system's default mail application repeatedly, potentially leading to excessive resource consumption and system instability. This behavior represents a classic case of improper input validation and insufficient redirect handling, where the browser fails to properly sanitize or limit the number of mail application launches triggered by HTML content. The vulnerability specifically targets the browser's image loading mechanism and its subsequent processing of redirect chains that lead to protocol handlers.
The operational impact of this vulnerability is significant as it allows remote attackers to perform denial of service attacks against targeted systems. An attacker can craft malicious HTML pages that, when loaded by an affected browser, cause the system to launch the mail application repeatedly, consuming system resources and potentially making the system unresponsive. This type of attack can be particularly effective in environments where users frequently browse untrusted web content or when the mail application is set to automatically launch when mailto: URLs are encountered. The attack vector is straightforward and requires minimal technical expertise, making it a popular choice for casual attackers seeking to disrupt user experience or system availability.
Mitigation strategies for this vulnerability include updating to the patched versions of Firefox and SeaMonkey where the issue has been addressed through improved redirect handling and limitations on protocol handler launches. Security practitioners should implement browser hardening measures such as disabling automatic mailto: URL handling or configuring browsers to require user confirmation before launching external applications. Network-level protections can include web application firewalls that detect and block malicious redirect patterns, though such measures are less effective against direct browser exploitation. The vulnerability demonstrates the importance of proper input validation and redirect chain handling in web browsers, aligning with ATT&CK technique T1203 for legitimate program execution and T1499 for network denial of service. Organizations should also consider implementing user education about avoiding untrusted web content and maintaining updated browser software to prevent exploitation of such vulnerabilities.