CVE-2018-5259 in DiscuzX
Summary
by MITRE
Discuz! DiscuzX X3.4 allows remote authenticated users to bypass intended attachment-deletion restrictions via a modified aid parameter.
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Analysis
by VulDB Data Team • 12/20/2019
The vulnerability identified as CVE-2018-5259 affects Discuz! DiscuzX version X3.4, a widely used forum software platform that powers numerous online communities and discussion forums. This security flaw represents a critical access control bypass issue that undermines the intended security mechanisms protecting attachment files within the forum environment. The vulnerability specifically targets the authorization controls that govern who can delete attachments, creating a pathway for authenticated attackers to circumvent these protections through manipulation of a single parameter.
The technical exploitation of this vulnerability occurs through manipulation of the aid parameter within the attachment deletion functionality. When users attempt to delete attachments, the system typically validates their permissions based on the attachment identifier and the user's authorization level. However, in this case, authenticated users can modify the aid parameter to reference attachments they should not be able to delete, effectively bypassing the intended access controls. This flaw falls under the category of improper access control as defined by CWE-285, which specifically addresses scenarios where systems fail to properly enforce authorization checks for operations that should be restricted to authorized users.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can enable attackers to manipulate forum content and potentially compromise the integrity of the entire platform. An attacker with valid user credentials can exploit this weakness to delete attachments that belong to other users, potentially removing evidence of discussions, compromising sensitive information, or disrupting the forum's functionality. This type of vulnerability can also facilitate data integrity attacks where malicious actors systematically remove attachments to disrupt community discussions or remove evidence of inappropriate content that might otherwise be flagged by administrators.
The security implications of this vulnerability align with ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate system access. Attackers leveraging this vulnerability can maintain persistence within the forum environment while performing unauthorized actions that would otherwise be restricted. The vulnerability also demonstrates characteristics of privilege escalation through parameter manipulation, where a simple modification of input parameters allows attackers to gain unauthorized access to resources that should be protected by access control mechanisms.
Organizations using Discuz! DiscuzX X3.4 should implement immediate mitigations including patching the software to the latest available version that addresses this access control flaw. Additionally, administrators should review and strengthen their access control policies, ensuring that proper authorization checks are in place for all attachment-related operations. The vulnerability highlights the importance of input validation and parameter sanitization within web applications, particularly for authenticated operations that involve resource manipulation. Security monitoring should be enhanced to detect unusual attachment deletion patterns that might indicate exploitation attempts. Organizations should also consider implementing additional access control layers through web application firewalls or other security controls that can help detect and prevent parameter manipulation attempts targeting this specific vulnerability.