CVE-2019-20848 in Mattermost Mobile App
Summary
by MITRE
An issue was discovered in Mattermost Mobile Apps before 1.26.0. The Quick Reply feature mishandles crafted replies.
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Analysis
by VulDB Data Team • 10/25/2020
The vulnerability identified as CVE-2019-20848 represents a critical security flaw within the Mattermost mobile application ecosystem affecting versions prior to 1.26.0. This issue specifically targets the Quick Reply functionality that users employ to rapidly respond to messages within the collaborative communication platform. The flaw manifests in how the application processes and handles crafted replies, creating potential attack vectors that could be exploited by malicious actors to compromise user sessions or execute unauthorized actions. Mattermost, as a popular enterprise communication platform, serves organizations requiring secure messaging capabilities, making vulnerabilities in its mobile clients particularly concerning for enterprise security posture.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the Quick Reply feature's code execution path. When users engage the quick reply functionality, the application processes the input text through a series of parsing and rendering operations that fail to properly handle maliciously crafted payloads. This improper handling creates opportunities for code injection or command execution within the mobile application context. The vulnerability aligns with CWE-20, which specifically addresses "Improper Input Validation," and potentially relates to CWE-79, "Cross-site Scripting," when considering the mobile application's rendering behavior. Attackers could exploit this weakness by crafting specially formatted replies containing malicious scripts or commands that bypass the application's security controls during the parsing phase.
The operational impact of CVE-2019-20848 extends beyond simple data compromise, as it could enable attackers to gain unauthorized access to user accounts, execute arbitrary code within the mobile application environment, or potentially escalate privileges within the Mattermost ecosystem. Mobile applications are particularly vulnerable to such attacks due to their direct interaction with device resources and the limited sandboxing capabilities compared to web-based interfaces. The vulnerability could be leveraged to perform actions such as accessing sensitive conversations, modifying user permissions, or even establishing persistent backdoors within the mobile application. From an attacker's perspective, this flaw represents a valuable entry point into enterprise communication networks where Mattermost is deployed, potentially allowing lateral movement and information exfiltration. The ATT&CK framework categorizes this type of vulnerability under T1059, "Command and Scripting Interpreter," and potentially T1071, "Application Layer Protocol," as the exploitation involves executing commands through the application's interface.
Organizations utilizing Mattermost mobile applications must prioritize immediate remediation of this vulnerability through the deployment of version 1.26.0 or later, which includes proper input validation and sanitization controls for the Quick Reply feature. Security teams should implement network monitoring to detect potential exploitation attempts and conduct comprehensive vulnerability assessments of their Mattermost deployments to identify any other instances of similar flaws. The mitigation strategy should also include user education regarding the dangers of interacting with untrusted replies and implementing additional security controls such as network segmentation and application whitelisting where appropriate. Organizations should also consider implementing mobile device management solutions to enforce security policies and ensure timely patch deployment across all mobile endpoints. The vulnerability underscores the importance of thorough input validation in mobile application development and highlights the need for continuous security testing throughout the software development lifecycle to prevent similar issues from emerging in future releases.