CVE-2006-6375 in SMF
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in display.php in Simple Machines Forum (SMF) 1.1 Final and earlier allows remote attackers to inject arbitrary web script or HTML via the contents of a file that is uploaded with the image parameter set, which can be interpreted as script by Internet Explorer s automatic type detection.
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Analysis
by VulDB Data Team • 08/10/2018
The vulnerability described in CVE-2006-6375 represents a critical cross-site scripting flaw within Simple Machines Forum version 1.1 Final and earlier implementations. This security weakness resides in the display.php script which processes file uploads and handles image parameters, creating an avenue for malicious actors to execute arbitrary web scripts or HTML code within the context of affected user sessions. The vulnerability specifically leverages Internet Explorer's automatic type detection mechanism, which can misinterpret uploaded files as executable scripts when certain parameters are manipulated during the upload process.
The technical exploitation of this vulnerability occurs through a carefully crafted file upload attack vector where attackers can bypass normal file validation mechanisms by manipulating the image parameter in the upload process. When the vulnerable forum software processes these specially crafted uploads, it fails to properly sanitize or validate the content, allowing malicious payloads to be stored and subsequently executed when other users view the uploaded content. This flaw directly relates to CWE-79 which classifies cross-site scripting vulnerabilities as weaknesses in web applications that allow attackers to inject malicious scripts into web pages viewed by other users.
The operational impact of this vulnerability extends beyond simple script execution to potentially enable full session hijacking, credential theft, and unauthorized administrative access within the compromised forum environment. Attackers can craft malicious files that appear benign but contain embedded scripts designed to steal cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users. The exploitation becomes particularly dangerous due to Internet Explorer's automatic type detection feature which can interpret certain file types as executable scripts without explicit user confirmation, making the attack surface significantly broader than typical XSS vulnerabilities.
Security professionals should consider this vulnerability in the context of the ATT&CK framework under the technique T1566 for "Phishing" and T1059 for "Command and Scripting Interpreter" as it enables attackers to establish persistent access through malicious file uploads. The vulnerability demonstrates a classic lack of input validation and output encoding that should be addressed through proper security controls including strict file type validation, content sanitization, and proper parameter handling. Organizations using affected versions of SMF should immediately implement patches or upgrade to supported versions while also conducting comprehensive security assessments of their web applications to identify similar input validation weaknesses that could be exploited through similar attack vectors.
The remediation approach must address the fundamental flaw in parameter handling within the display.php script by implementing comprehensive input validation, output encoding, and proper file type checking mechanisms. Security measures should include disabling automatic type detection for uploaded content, implementing strict file extension validation, and ensuring that all user-supplied content is properly sanitized before storage or display. Additionally, organizations should deploy web application firewalls and implement content security policies to provide additional layers of protection against similar exploitation techniques that could target other components of the web application stack.