CVE-2018-21258 in Mattermost Server
Summary
by MITRE
An issue was discovered in Mattermost Server before 5.1. It allows attackers to cause a denial of service via the invite_people slash command.
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Analysis
by VulDB Data Team • 10/25/2020
The vulnerability identified as CVE-2018-21258 represents a denial of service flaw within the Mattermost Server platform prior to version 5.1. This security issue specifically affects the invite_people slash command functionality, which is a core component of the Mattermost communication platform designed for team collaboration and user management. The vulnerability arises from insufficient input validation and sanitization within the slash command processing mechanism, creating an exploitable condition that can be leveraged by malicious actors to disrupt normal service operations.
The technical nature of this vulnerability stems from improper handling of user inputs within the invite_people slash command implementation. When an attacker submits a crafted payload through this command, the system fails to adequately validate or sanitize the input parameters, potentially leading to resource exhaustion or execution flow disruption. This type of flaw falls under the CWE-400 category of Uncontrolled Resource Consumption, where the system's resources become depleted due to malformed input processing. The vulnerability's impact is particularly concerning because slash commands are integral to Mattermost's user interaction model, making this attack vector easily accessible to potential threat actors.
From an operational perspective, this denial of service vulnerability can severely impact organizations relying on Mattermost for their team communication needs. Attackers can exploit this weakness to repeatedly send malicious payloads through the invite_people command, causing the server to consume excessive CPU cycles, memory resources, or other system components. The disruption affects legitimate users who may lose access to critical communication channels, potentially impacting business continuity and operational efficiency. The vulnerability is particularly dangerous in enterprise environments where Mattermost serves as a primary communication platform for distributed teams, as it can effectively shut down collaboration services for extended periods.
Mitigation strategies for CVE-2018-21258 should focus on immediate patching of the Mattermost Server to version 5.1 or later, which contains the necessary fixes for the input validation issues. Organizations should also implement network-level controls to monitor and restrict slash command usage patterns, particularly those involving user invitation functionality. The implementation of rate limiting mechanisms and input sanitization measures can provide additional defense-in-depth layers. From an ATT&CK framework perspective, this vulnerability aligns with the T1499.004 technique related to Network Denial of Service, and organizations should consider implementing monitoring solutions that can detect anomalous slash command usage patterns. Security teams should also conduct regular vulnerability assessments to identify similar input validation weaknesses in other command processing mechanisms within their communication platforms, as this type of flaw can potentially exist in other parts of the system architecture.