CVE-2005-2817 in Simple Machines
Summary
by MITRE
Simple Machines Forum (SMF) 1-0-5 and earlier supports the use of URLs for avatar images, which allows remote attackers to monitor sensitive information of forum visitors such as IP address and user agent, as demonstrated using a PHP script on a malicious server.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 06/09/2019
The vulnerability described in CVE-2005-2817 represents a significant privacy and security flaw within Simple Machines Forum versions 1.0.5 and earlier. This issue stems from the forum software's handling of avatar image URLs, specifically when users configure their profiles to display avatars hosted on external servers. The flaw allows malicious actors to construct PHP scripts on compromised servers that can capture and log sensitive visitor information, creating a persistent surveillance mechanism that undermines user privacy and data protection principles.
The technical implementation of this vulnerability exploits the trust model inherent in web applications where users expect avatar images to be displayed without additional security considerations. When forum visitors access pages containing malicious avatar URLs, their browsers attempt to fetch the avatar images from remote servers, inadvertently transmitting identifying information such as IP addresses and user agent strings to the attacker's server. This occurs because the forum software does not implement proper validation or sanitization of avatar URL parameters, allowing arbitrary external URLs to be specified and executed without adequate security controls.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables sophisticated tracking and profiling capabilities that can be leveraged for various malicious purposes including targeted attacks, credential harvesting, and user behavior analysis. Security researchers have classified this issue as a privacy violation and information leakage vulnerability that directly conflicts with fundamental web security principles and user expectations regarding anonymous browsing. The flaw demonstrates how seemingly innocuous features can become attack vectors when proper input validation and security controls are absent from web application code.
This vulnerability aligns with CWE-200 (Information Exposure) and CWE-116 (Improper Encoding or Escaping of Output) categories, representing a classic example of how external resource handling can be exploited for surveillance purposes. From an adversarial perspective, this flaw maps to ATT&CK technique T1566.001 (Phishing with Social Engineering) and T1071.004 (Application Layer Protocol: DNS) as attackers can leverage the avatar system to gather intelligence about victims. The vulnerability also relates to T1005 (Data from Local System) and T1082 (System Information Discovery) as it enables collection of system-level information about forum visitors through indirect means.
Mitigation strategies for this vulnerability require immediate implementation of proper URL validation and sanitization within the forum software, ensuring that avatar URLs are restricted to known, trusted domains or properly encoded to prevent execution of malicious code. Security patches should enforce strict input validation to prevent arbitrary external URLs from being processed as avatar sources, while also implementing proper access controls to prevent unauthorized modification of user profile settings. Organizations should also consider implementing network monitoring solutions to detect suspicious outbound connections that may indicate exploitation of this vulnerability, and establish proper security awareness training for administrators to prevent configuration errors that could lead to similar issues. The fix should also include logging mechanisms to track avatar URL access patterns and detect potential abuse of the system.