CVE-2019-7690 in MobaXterm Personal Edition
Summary
by MITRE
In MobaTek MobaXterm Personal Edition v11.1 Build 3860, the SSH private key and its password can be retrieved from process memory for the lifetime of the process, even after the user disconnects from the remote SSH server. This affects Passwordless Authentication that has a Password Protected SSH Private Key.
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Analysis
by VulDB Data Team • 09/17/2023
The vulnerability identified as CVE-2019-7690 represents a critical memory exposure issue within MobaTek MobaXterm Personal Edition version 11.1 Build 3860. This flaw manifests in the improper handling of SSH private key material and associated passwords within the application's memory space, creating persistent security risks that extend beyond normal user session boundaries. The vulnerability specifically impacts users who employ password-protected SSH private keys for authentication purposes, where the private key remains accessible in memory even after disconnection from remote servers.
The technical implementation of this vulnerability stems from inadequate memory management practices within the MobaXterm application. When users establish SSH connections using password-protected private keys, the application loads both the private key and its corresponding password into memory for the duration of the process lifecycle. This design flaw violates fundamental security principles regarding credential handling and memory sanitization. The private key material and password remain accessible in the process memory space regardless of whether the user has disconnected from the remote server, creating a persistent exposure window that can be exploited by malicious actors with appropriate privileges.
From an operational impact perspective, this vulnerability creates significant risks for organizations and individual users who rely on SSH-based authentication for remote system access. The persistent exposure of private keys in memory means that attackers who gain access to the system or can execute code within the application context can potentially extract sensitive authentication material. This vulnerability directly impacts the security posture of users who depend on passwordless authentication mechanisms, as the private key remains accessible even after session termination. The implications extend beyond simple credential theft to potential privilege escalation and unauthorized access to multiple systems that rely on the compromised key for authentication.
The vulnerability maps to CWE-200 (Information Exposure) and CWE-312 (Cleartext Storage of Sensitive Information) within the Common Weakness Enumeration framework, highlighting the exposure of sensitive data in memory and the insecure storage of authentication credentials. From an ATT&CK framework perspective, this vulnerability enables techniques such as credential dumping and privilege escalation through the access to stored credentials in memory. The threat actor can leverage this weakness to maintain persistent access to systems, as the compromised private key can be used for authentication without requiring additional user interaction or re-authentication.
Mitigation strategies for this vulnerability should include immediate application updates to versions that address the memory handling issues, implementation of memory sanitization practices, and consideration of alternative authentication mechanisms. Users should avoid using password-protected private keys in environments where memory exposure risks are significant, and organizations should implement monitoring for unauthorized process memory access. The recommended approach involves updating to patched versions of MobaXterm, implementing additional security controls such as key rotation policies, and ensuring that sensitive authentication material is properly cleared from memory upon session termination. Organizations should also consider implementing process monitoring and memory analysis tools to detect potential exploitation attempts targeting this vulnerability.