CVE-2023-2786 in Server
Summary
by MITRE • 06/16/2023
Mattermost fails to properly check the permissions when executing commands allowing a member with no permissions to post a message in a channel to actually post it by executing channel commands.
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Analysis
by VulDB Data Team • 07/14/2023
The vulnerability identified as CVE-2023-2786 represents a critical access control flaw within the Mattermost collaborative platform that undermines the fundamental security model of channel-based communications. This issue stems from improper permission validation during command execution processes, creating a scenario where users lacking appropriate authorization can manipulate system behaviors through specific command sequences. The flaw exists in the platform's command processing logic where the system fails to adequately verify user permissions before executing channel-related operations, thereby allowing unauthorized access to channel functionalities that should be restricted to authorized participants only.
The technical implementation of this vulnerability exploits the gap between the permission checking mechanisms and command execution pathways within Mattermost's architecture. When a user attempts to execute channel commands, the system should validate whether the requesting user possesses the necessary privileges to perform such operations. However, the flawed implementation allows a user with minimal permissions to bypass these checks by leveraging specific command patterns that ultimately result in message posting capabilities. This creates a privilege escalation scenario where unauthorized users can effectively gain access to channel posting functionalities that are typically restricted to moderators or administrators. The vulnerability manifests through the command execution flow where permission validation occurs after command parsing but before actual execution, leaving a window where unauthorized users can manipulate the system behavior.
The operational impact of CVE-2023-2786 extends beyond simple unauthorized message posting, as it fundamentally compromises the integrity of channel access controls within Mattermost environments. Organizations relying on Mattermost for secure communications may experience unauthorized access to sensitive channels, potential data leakage through message posting capabilities, and disruption of established communication protocols. The vulnerability affects any Mattermost deployment where channel-based access controls are implemented, particularly impacting environments with strict compliance requirements or those handling confidential information. Security teams may face challenges in monitoring and detecting unauthorized activities, as the compromised users can operate within the system without triggering standard access control alerts. This vulnerability also undermines the trust model that organizations build around their collaboration platforms, potentially leading to reputational damage and regulatory compliance issues.
Mitigation strategies for CVE-2023-2786 should prioritize immediate patch deployment from Mattermost to address the core permission validation flaw. Organizations should implement additional monitoring measures to detect anomalous command execution patterns and establish more robust audit trails for channel-related operations. Network segmentation and access control policies should be reviewed to minimize the impact of potential exploitation, while regular security assessments should verify the proper implementation of access controls. The vulnerability aligns with CWE-284 which addresses improper access control, and may map to ATT&CK techniques involving privilege escalation and command execution. Security teams should also consider implementing temporary workarounds such as restricting channel command execution permissions or disabling specific command functionalities until the official patch is applied. Regular security training for administrators on identifying and responding to access control vulnerabilities should be implemented as part of a comprehensive security posture improvement initiative.