CVE-2006-6626 in Moodle
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in an unspecified component of Moodle 1.5 allows remote attackers to inject arbitrary web script or HTML via a javascript URI in the SRC attribute of an IMG element. NOTE: The provenance of this information is unknown; the details are obtained solely from third party information. NOTE: It is unclear whether this candidate overlaps CVE-2006-4784 or CVE-2006-4941.
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Analysis
by VulDB Data Team • 08/10/2018
This cross-site scripting vulnerability exists within Moodle 1.5's handling of HTML content, specifically in how the platform processes image source attributes. The flaw occurs when the system fails to properly sanitize or validate javascript URIs embedded within the src attribute of img elements, allowing malicious actors to inject arbitrary web scripts or HTML code. This vulnerability represents a classic XSS attack vector where attacker-controlled content can be executed in the context of other users' browsers, potentially leading to session hijacking, credential theft, or unauthorized actions within the Moodle environment.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding mechanisms within Moodle's content processing pipeline. When the system renders HTML content containing img tags with javascript URIs in their src attributes, it does not adequately filter or escape these dangerous elements before presenting them to end users. This weakness aligns with CWE-79, which categorizes cross-site scripting flaws as improper neutralization of input during web page generation, and represents a failure in proper HTML sanitization techniques. The vulnerability specifically targets the SRC attribute processing, making it a variant of the broader class of DOM-based XSS attacks that manipulate client-side execution contexts.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to establish persistent malicious presence within the Moodle learning management system. An attacker could craft malicious course materials or forum posts containing img tags with javascript URIs that would execute when other users view the content. This could lead to unauthorized access to user sessions, data exfiltration, or modification of course content. The vulnerability's remote nature means attackers need only find a way to inject the malicious content into the system, which could occur through user-generated content, forum posts, or even through compromised user accounts. According to ATT&CK framework, this represents a technique categorized under T1566 for initial access through web applications, with potential for T1078 for legitimate credential use and T1190 for exploitation of web applications.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input sanitization and output encoding mechanisms. Organizations should immediately upgrade to patched versions of Moodle where available, as version 1.5 is no longer supported and contains multiple known vulnerabilities. The remediation process must include implementing strict HTML filtering that removes or escapes javascript URIs from img src attributes, employing Content Security Policy headers to prevent execution of inline scripts, and conducting regular security audits of user-generated content. Additionally, administrators should implement proper access controls and monitoring to detect unauthorized content injection attempts. The vulnerability's classification as CWE-79 emphasizes the need for robust application-level security controls, including proper context-aware encoding and validation of all user-provided input before rendering it within the application's user interface.