CVE-2017-7489 in Moodle
Summary
by MITRE
In Moodle 2.x and 3.x, remote authenticated users can take ownership of arbitrary blogs by editing an external blog link.
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Analysis
by VulDB Data Team • 12/06/2022
The vulnerability identified as CVE-2017-7489 affects Moodle versions 2.x and 3.x, representing a critical security flaw that allows authenticated remote attackers to manipulate blog ownership permissions. This issue stems from insufficient input validation and access control mechanisms within the blogging functionality of the learning management system. The flaw specifically targets the external blog link editing feature, where malicious users can exploit the system's trust model to assume control over blogs they should not have access to. The vulnerability is classified under CWE-284 which addresses improper access control, and aligns with ATT&CK technique T1078 for valid accounts and T1068 for exploit private vulnerabilities. The security implications extend beyond simple privilege escalation as this allows attackers to modify content, potentially injecting malicious links or defacing public-facing educational resources.
The technical execution of this vulnerability involves leveraging the legitimate blog editing functionality to manipulate the ownership attributes of external blog entries. When authenticated users access the blog editing interface, the system fails to properly validate whether the current user has legitimate authorization to modify the target blog's ownership properties. This validation gap enables attackers to modify the blog owner field in external blog links, effectively transferring ownership to their own accounts without proper authentication. The flaw exists because the application does not maintain proper access control checks when processing blog ownership changes, particularly for external blog entries that are linked to the system. The vulnerability requires only authenticated access to the platform, making it particularly dangerous as it can be exploited by any user with valid credentials.
The operational impact of CVE-2017-7489 extends significantly beyond simple content manipulation, potentially compromising the integrity and trustworthiness of educational platforms. Organizations utilizing Moodle for academic content management face risks of unauthorized content modification, which could include malicious link injection, defacement of public blog sections, or the propagation of harmful information through educational networks. The vulnerability undermines the trust model of the learning management system, as it allows attackers to impersonate legitimate users and assume responsibility for educational content. This can lead to serious consequences including academic dishonesty accusations, compromised educational integrity, and potential legal implications for institutions. The attack vector is particularly concerning because it operates within the legitimate user workflow, making detection difficult and potentially allowing attackers to remain undetected for extended periods. Security monitoring systems may not flag this activity as anomalous since it occurs within normal user operations.
Mitigation strategies for CVE-2017-7489 should focus on implementing robust access control measures and input validation within the blogging subsystem. Organizations should immediately apply the official patches released by Moodle to address the vulnerability, as these updates contain necessary code modifications to properly validate blog ownership changes. System administrators should also consider implementing additional monitoring for blog ownership modifications, particularly for external blog entries, to detect unauthorized changes. The remediation process should include disabling unnecessary blog features for users who do not require them, implementing role-based access controls that restrict blog modification privileges, and conducting regular security audits of the blogging functionality. Organizations should also consider implementing network segmentation to limit access to blog-related features and establish automated alerting for suspicious blog ownership changes. The vulnerability serves as a reminder of the importance of proper access control implementation and the need for continuous security testing of educational platforms, particularly those handling sensitive academic content and user-generated materials.