CVE-2023-2831 in Server
Summary
by MITRE • 06/16/2023
Mattermost fails to unescape Markdown strings in a memory-efficient way, allowing an attacker to cause a Denial of Service by sending a message containing a large number of escaped characters.
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Analysis
by VulDB Data Team • 07/14/2023
The vulnerability identified as CVE-2023-2831 represents a critical denial of service flaw within the Mattermost collaboration platform that stems from improper handling of markdown string escaping mechanisms. This issue specifically affects how the system processes and renders markdown content, creating a scenario where malicious actors can exploit the memory management inefficiencies inherent in the platform's text processing pipeline. The flaw manifests when users send messages containing excessive numbers of escaped characters, which the system fails to properly unescape in a memory-efficient manner.
The technical root cause of this vulnerability lies in the markdown parsing implementation where the system does not adequately manage memory allocation during the unescaping process of markdown strings. When processing messages with large quantities of escaped characters such as backslashes, asterisks, or other markdown delimiters, the platform's memory consumption grows exponentially rather than linearly. This inefficient memory handling creates a condition where an attacker can craft specially formatted messages that consume excessive system resources, ultimately leading to service disruption. The vulnerability is classified under CWE-400 as a resource exhaustion issue, specifically manifesting as a denial of service condition through improper resource management during text processing operations.
The operational impact of this vulnerability extends beyond simple service disruption to potentially affect the entire Mattermost deployment's stability and availability. When exploited, the vulnerability allows attackers to consume significant memory resources, potentially causing the application server to become unresponsive or crash entirely. This can result in complete service unavailability for legitimate users, affecting team collaboration and communication within organizations that rely on Mattermost for their messaging infrastructure. The attack vector is particularly concerning because it requires minimal privileges and can be executed through normal message sending functionality, making it difficult to detect and prevent through traditional access control measures.
Mitigation strategies for CVE-2023-2831 should focus on implementing proper input validation and memory management within the markdown parsing pipeline. Organizations should deploy immediate patches or updates provided by Mattermost that address the specific memory handling inefficiencies in the markdown unescaping process. Additionally, implementing rate limiting on message processing and setting reasonable limits on the number of escaped characters permitted in individual messages can serve as effective defensive measures. Network-level monitoring should be enhanced to detect unusual memory consumption patterns that may indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004 for resource exhaustion and T1566.001 for social engineering through messaging platforms, emphasizing the need for both technical and operational security controls to address the threat effectively.