CVE-2016-7570 in Drupal
Summary
by MITRE
Drupal 8.x before 8.1.10 does not properly check for "Administer comments" permission, which allows remote authenticated users to set the visibility of comments for arbitrary nodes by leveraging rights to edit those nodes.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability identified as CVE-2016-7570 affects Drupal 8.x versions prior to 8.1.10 and represents a significant access control flaw that undermines the security model of the content management platform. This issue stems from insufficient permission validation within the comment management system, creating a scenario where authenticated users can manipulate comment visibility settings on nodes they do not have explicit administrative rights to manage. The flaw exists at the core level of Drupal's permission architecture, specifically in how the system validates user privileges when processing comment visibility modifications.
The technical implementation of this vulnerability exploits a gap in the Drupal 8 permission checking mechanism where the system fails to properly verify whether a user possesses the "Administer comments" permission before allowing them to modify comment visibility settings. While users may have legitimate rights to edit specific nodes, they should not be permitted to alter comment visibility for those nodes without proper administrative authorization. This oversight creates a privilege escalation pathway where users can manipulate comment visibility for any node they can edit, effectively bypassing the intended access controls that separate content editing from comment management administration.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it allows attackers to manipulate the visibility of comments on content they do not own or administrate. This capability can be leveraged for various malicious activities including hiding sensitive information, creating false narratives, or disrupting the intended discussion flow on content. The vulnerability particularly affects websites that rely heavily on user-generated content and comment systems, as it enables unauthorized modification of comment visibility settings that could be used to suppress legitimate feedback or manipulate public discourse. Attackers can exploit this flaw to set comments to hidden visibility for nodes they can edit, potentially hiding negative feedback or sensitive information that should remain visible to site visitors.
This vulnerability aligns with CWE-285, which addresses improper authorization in software systems, and represents a classic case of insufficient access control validation. The flaw demonstrates how permission boundaries can be improperly enforced in complex content management systems where multiple roles and capabilities must be carefully managed. From an attack perspective, this vulnerability maps to several ATT&CK techniques including privilege escalation and defense evasion, as attackers can manipulate comment visibility to hide their activities or suppress legitimate user feedback. The vulnerability also intersects with credential access patterns since it allows users to effectively bypass permission checks that should normally require administrative privileges.
Organizations affected by this vulnerability should prioritize immediate patching to Drupal 8.1.10 or later versions, which contain the necessary permission validation fixes. Additionally, system administrators should conduct thorough audits of user roles and permissions to ensure that only trusted users have access to comment management functions. Security monitoring should be enhanced to detect unusual comment visibility changes, particularly when these modifications occur in conjunction with node editing activities. The vulnerability underscores the importance of comprehensive permission testing in CMS platforms and highlights the need for regular security assessments of access control mechanisms. Organizations should also consider implementing additional monitoring controls that can detect unauthorized changes to comment visibility settings, as these modifications may indicate attempted privilege escalation or malicious activity within the system.