CVE-2023-2791 in Server
Summary
by MITRE • 06/16/2023
When creating a playbook run via the /dialog API, Mattermost fails to validate all parameters, allowing an authenticated attacker to edit an arbitrary channel post.
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Analysis
by VulDB Data Team • 06/16/2023
The vulnerability identified as CVE-2023-2791 resides within the Mattermost collaboration platform's /dialog API endpoint, representing a critical authorization and input validation flaw that enables authenticated attackers to manipulate channel posts beyond their intended scope. This weakness specifically manifests during the creation of playbook runs through the dialog interface, where the system fails to properly validate all incoming parameters, creating an exploitable vector for privilege escalation and data manipulation.
The technical flaw stems from insufficient parameter validation within the playbook execution workflow, allowing attackers who have authenticated access to the platform to craft malicious requests that bypass normal access controls. When an attacker submits a request to the /dialog API endpoint to initiate a playbook run, the system processes certain parameters while neglecting to validate others, particularly those related to channel identification and post modification permissions. This incomplete validation creates a path where an attacker can specify arbitrary channel identifiers and post modification operations, effectively granting them the ability to edit content in channels they should not normally have access to.
The operational impact of this vulnerability extends beyond simple data manipulation, as it represents a fundamental breakdown in the platform's access control mechanisms and could enable attackers to compromise the integrity of communication channels. An authenticated attacker could potentially modify critical messages, inject malicious content, alter discussion threads, or even remove important information from channels, undermining the trust and reliability of the collaboration platform. The vulnerability affects the core messaging functionality of Mattermost, potentially exposing sensitive organizational communications to unauthorized modification.
This flaw aligns with CWE-20, which describes "Improper Input Validation" as a common vulnerability pattern where input validation is insufficient or missing entirely. The issue also relates to CWE-798, "Use of Hard-coded Credentials," and CWE-862, "Missing Authorization," as it demonstrates inadequate authorization checks during API operations. From an ATT&CK framework perspective, this vulnerability maps to T1078.004, "Valid Accounts: Cloud Accounts," and T1566.001, "Phishing: Spearphishing Attachment," as attackers could leverage legitimate authenticated sessions to exploit this weakness. The vulnerability could also contribute to T1496, "Resource Hijacking," if attackers use modified posts to redirect users to malicious content or if the platform's reputation is damaged through unauthorized modifications.
Organizations should implement immediate mitigations including thorough input validation across all API endpoints, particularly those handling playbook and workflow operations, and enforcement of strict authorization checks for all channel modification operations. The platform should be updated to version 7.9.1 or later, which includes patches addressing this specific vulnerability. Additionally, administrators should review and tighten access controls for playbook execution features, implement monitoring for unusual API activity patterns, and ensure that all authenticated users have appropriate least-privilege access to channels and posts. Regular security audits of API endpoints and parameter validation mechanisms should be conducted to prevent similar vulnerabilities from emerging in other parts of the system, with particular attention to workflows involving cross-channel operations and collaborative features that may expose similar validation gaps.