CVE-2019-20852 in Mattermost Mobile App
Summary
by MITRE
An issue was discovered in Mattermost Mobile Apps before 1.26.0. Local logging is not blocked for sensitive information (e.g., server addresses or message content).
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Analysis
by VulDB Data Team • 10/25/2020
The vulnerability identified as CVE-2019-20852 represents a significant security flaw in the Mattermost mobile applications affecting versions prior to 1.26.0. This issue stems from inadequate handling of sensitive data within the application's logging mechanisms, creating potential exposure pathways for confidential information. The flaw manifests in the application's failure to properly sanitize or block sensitive data from being recorded in local log files, which can be accessed by unauthorized parties or malicious actors with system-level privileges. The vulnerability specifically impacts mobile environments where local storage and logging capabilities are utilized for debugging and operational purposes, creating a persistent risk vector that extends beyond the application's immediate operational boundaries.
The technical implementation of this vulnerability involves the application's logging subsystem not properly filtering or masking sensitive information during the logging process. When mobile applications generate diagnostic logs, they typically capture various operational data points including user interactions, system events, and network communications. In the case of Mattermost, the logging mechanism fails to recognize and exclude sensitive data elements such as server addresses, message content, authentication tokens, or other confidential information that should remain protected. This represents a deviation from established security practices and proper data handling protocols, where sensitive information should be either redacted, encrypted, or completely excluded from non-essential logging streams. The flaw aligns with CWE-532, which describes the insertion of sensitive information into log files, and demonstrates poor information flow control within the application's security architecture.
The operational impact of this vulnerability extends beyond simple data exposure, creating multiple attack vectors that could be exploited by threat actors. Local log files on mobile devices often contain rich operational data that can be leveraged for further attacks, including reconnaissance activities, credential harvesting, or privilege escalation attempts. Attackers with physical access to compromised devices or those who have gained system-level privileges can access these log files and extract sensitive information that could be used to compromise additional systems or accounts. The vulnerability particularly affects enterprise environments where Mattermost is used for secure communications, as the exposure of server addresses and message content could lead to targeted attacks against the underlying infrastructure. This represents a significant concern for organizations following security frameworks such as NIST SP 800-53, which emphasizes the importance of protecting sensitive data in all system components, including logging mechanisms.
Mitigation strategies for this vulnerability require immediate application updates to version 1.26.0 or later, which includes proper logging sanitization mechanisms. Organizations should implement comprehensive log management policies that include regular log file audits, access controls, and monitoring for unauthorized access attempts. The implementation of secure coding practices should ensure that all logging operations follow proper data handling protocols, including the use of log filtering mechanisms that automatically identify and exclude sensitive information. Security teams should also consider deploying mobile device management solutions that can restrict or monitor logging capabilities on enterprise devices. From an ATT&CK framework perspective, this vulnerability relates to techniques such as T1070.004 (Indicator Removal on Host) and T1003.001 (OS Credential Dumping), as compromised devices with access to sensitive logs could provide attackers with additional attack surface and information for further compromise. The vulnerability underscores the critical importance of maintaining up-to-date security practices and proper information flow control in mobile application development, particularly when handling sensitive communications data.