CVE-2014-3549 in Moodle
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the get_description function in lib/classes/event/user_login_failed.php in Moodle 2.7.x before 2.7.1 allows remote attackers to inject arbitrary web script or HTML via a crafted username that is improperly handled during the logging of an invalid login attempt.
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Analysis
by VulDB Data Team • 06/04/2017
The CVE-2014-3549 vulnerability represents a critical cross-site scripting flaw within the Moodle learning management system that specifically targets the user_login_failed.php component. This vulnerability exists in Moodle versions 2.7.x prior to 2.7.1 and stems from improper input validation within the get_description function. The flaw allows remote attackers to execute malicious scripts by manipulating the username field during failed login attempts, creating a persistent security risk that can affect all users within the system. The vulnerability operates by exploiting the lack of proper sanitization when processing user input during authentication failure logging, enabling attackers to inject malicious HTML or JavaScript code that gets executed in the context of other users' browsers.
This vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically representing a reflected XSS attack vector where malicious code is injected into the system logs and subsequently rendered to users who view these logs. The attack chain begins with an attacker crafting a malicious username containing script tags, submitting it as part of a failed login attempt, and then the vulnerable code improperly handles this input by storing it directly into the system logs without adequate sanitization. When legitimate administrators or users view these failed login records, the stored malicious script executes in their browser context, potentially leading to session hijacking, data theft, or further exploitation of the system. The vulnerability demonstrates a fundamental flaw in input validation and output encoding practices within the Moodle codebase, particularly in how it handles user-supplied data during error logging operations.
The operational impact of this vulnerability extends beyond simple script execution, as it can facilitate more sophisticated attacks within the Moodle environment. Attackers could leverage this vulnerability to steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users through the exploitation of the XSS vector. The vulnerability is particularly dangerous in educational environments where Moodle systems often contain sensitive student data, course materials, and administrative functions. The persistent nature of the vulnerability means that once exploited, the malicious code can continue to affect users until the system is patched and the malicious entries are removed from the logs. This creates a window of opportunity for attackers to conduct reconnaissance, establish persistent access, or execute more complex attacks such as privilege escalation or data exfiltration.
Mitigation strategies for CVE-2014-3549 should focus on immediate patching of affected Moodle installations to version 2.7.1 or later, which contains the necessary fixes for input validation and sanitization. Organizations should also implement proper input filtering and output encoding mechanisms throughout the system to prevent similar vulnerabilities from occurring in other components. Security measures should include regular audit of system logs for suspicious entries, implementation of web application firewalls to detect and block malicious payloads, and comprehensive user education about the risks of clicking on suspicious links or entering unknown data. The vulnerability highlights the importance of following secure coding practices and proper input validation as outlined in the OWASP Top Ten security standards, particularly emphasizing the need for defense-in-depth strategies that protect against both known and unknown attack vectors. Additionally, implementing proper access controls and monitoring for failed login attempts can help detect potential exploitation attempts and provide early warning of active attacks against the system.