CVE-2001-0556 in NEdit
Summary
by MITRE
The Nirvana Editor (NEdit) 5.1.1 and earlier allows a local attacker to overwrite other users files via a symlink attack on (1) backup files or (2) temporary files used when nedit prints a file or portions of a file.
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Analysis
by VulDB Data Team • 07/19/2019
The Nirvana Editor version 5.1.1 and earlier contains a critical local privilege escalation vulnerability that stems from improper handling of temporary and backup files during print operations. This vulnerability creates a race condition scenario where a local attacker can exploit the editor's file creation processes to overwrite files owned by other users on the system. The flaw specifically manifests when nedit generates temporary files or backup copies during print operations, which are created without adequate security measures to prevent symbolic link attacks. The vulnerability exists because the application does not validate the existence or ownership of these temporary files before creating them, allowing malicious users to establish symbolic links with the same names that nedit intends to use.
This security weakness falls under the category of symlink-based attacks and can be categorized as a race condition vulnerability that enables unauthorized file overwrites. The technical implementation of the flaw occurs when nedit creates temporary files with predictable names during print operations, such as when printing entire files or specific sections of documents. Attackers can create symbolic links with the same names in the target directory before nedit attempts to create the actual temporary files, causing nedit to write data to the attacker-controlled symbolic link target instead of the intended temporary file location. This type of vulnerability is particularly dangerous in multi-user environments where different users may have varying levels of access and permissions.
The operational impact of this vulnerability extends beyond simple file overwrites and can potentially lead to privilege escalation, data corruption, or information disclosure. When an attacker successfully exploits this weakness, they can overwrite files with malicious content, potentially gaining access to sensitive data or disrupting system operations. The vulnerability affects all users who have access to the nedit application and can be exploited by any local user who can create symbolic links in the directories where nedit creates temporary files. This creates a significant risk in shared computing environments where multiple users interact with the same system resources and where the attacker may not require elevated privileges to execute the attack.
The vulnerability aligns with several cybersecurity frameworks and threat models, including the MITRE ATT&CK framework where it would be classified under techniques related to privilege escalation and local persistence. It also corresponds to CWE-377, which addresses insecure temporary file creation, and CWE-378, which covers the creation of temporary files with insecure permissions. Organizations using nedit versions 5.1.1 and earlier should immediately implement mitigations including upgrading to patched versions of the application, implementing proper file permission controls, and monitoring for unauthorized symbolic link creation in directories where nedit operates. Additionally, system administrators should consider implementing mandatory access controls and regular security audits to detect and prevent exploitation of such vulnerabilities in their environments.