CVE-2011-2916 in qtnx
Summary
by MITRE
qtnx 0.9 stores non-custom SSH keys in a world-readable configuration file. If a user has a world-readable or world-executable home directory, another local system user could obtain the private key used to connect to remote NX sessions.
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Analysis
by VulDB Data Team • 02/20/2024
The vulnerability described in CVE-2011-2916 affects qtnx version 0.9, a graphical client for connecting to NoMachine NX sessions. This issue represents a classic privilege escalation and information disclosure vulnerability that arises from improper file permission management within the application's configuration handling mechanisms. The flaw specifically manifests when the application stores SSH private keys in configuration files that are accessible to all system users, creating a significant security risk for multi-user environments.
The technical root cause of this vulnerability lies in the application's failure to properly secure sensitive authentication materials. When qtnx 0.9 generates or stores SSH keys for NX session connections, it places these credentials in configuration files with world-readable permissions. This design flaw directly violates fundamental security principles regarding the protection of private cryptographic keys and authentication materials. The vulnerability is particularly dangerous because it leverages the inherent trust model of Unix-like systems where file permissions are the primary mechanism for access control. The issue becomes exploitable when a user's home directory or a parent directory has world-readable or world-executable permissions, allowing any local user to access the configuration file containing the private SSH key.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable unauthorized remote access to NX sessions. An attacker with local system access could extract the private SSH key and use it to authenticate to remote NX servers, effectively bypassing the normal authentication mechanisms. This scenario creates a privilege escalation pathway where a low-privilege local user can gain access to systems that would normally require proper authentication credentials. The vulnerability affects any system where qtnx 0.9 is installed and used, particularly in shared hosting environments or multi-user systems where users may not trust each other. The risk is amplified in environments where users have access to each other's home directories or where directory permissions are not properly enforced.
From a cybersecurity perspective, this vulnerability aligns with CWE-732: Incorrect Permission Assignment for Critical Resource, which specifically addresses cases where critical system resources receive incorrect access permissions. The flaw also relates to ATT&CK technique T1552.001: Unsecured Credentials, which covers methods for accessing credentials stored in files. The vulnerability demonstrates the importance of least privilege principles in application design and highlights the need for proper input validation and secure configuration management. Mitigation strategies should include immediate permission fixes to restrict access to configuration files containing authentication materials, proper implementation of secure file handling practices, and regular security audits of application configurations. System administrators should ensure that qtnx 0.9 is either updated to a version that properly handles file permissions or that appropriate access controls are implemented to prevent unauthorized access to sensitive configuration files. The vulnerability underscores the critical need for developers to follow secure coding practices and for organizations to implement proper security controls around credential storage and access management.