CVE-2001-0141 in Mgetty
Summary
by MITRE
mgetty 1.1.22 allows local users to overwrite arbitrary files via a symlink attack in some configurations.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 07/19/2019
The vulnerability identified as CVE-2001-0141 affects mgetty version 1.1.22, a widely used getty implementation for handling modem connections and terminal logins in Unix-like systems. This flaw represents a classic symlink attack vector that exploits insecure temporary file handling mechanisms within the software's operation. The vulnerability specifically manifests when mgetty processes incoming connections and creates temporary files during its execution lifecycle, creating opportunities for local attackers to manipulate file system permissions and overwrite arbitrary files on the system.
The technical implementation of this vulnerability stems from mgetty's failure to properly validate or secure temporary file creation processes. When the software operates in certain configurations, it creates temporary files in predictable locations without adequate security measures to prevent symbolic link manipulation. Attackers can exploit this by creating malicious symbolic links in directories where mgetty expects to create temporary files, effectively causing the software to write data to locations controlled by the attacker rather than intended target files. This type of attack falls under the broader category of time-of-check to time-of-use vulnerabilities, where the security check occurs at a different moment than the actual file operation.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities, as it can potentially enable privilege escalation attacks when mgetty runs with elevated permissions. Since mgetty typically handles modem connections and may be configured to run with root privileges for certain operations, successful exploitation could allow attackers to overwrite critical system files, configuration files, or even binaries that are executed by the system. The attack requires local access to the system but can be particularly dangerous in multi-user environments where attackers might gain access through various means such as compromised accounts or other vulnerabilities. This vulnerability demonstrates the importance of proper file system security practices and the dangers of insecure temporary file handling in system utilities.
Mitigation strategies for CVE-2001-0141 primarily focus on updating to patched versions of mgetty where the temporary file handling has been corrected to prevent symbolic link attacks. System administrators should ensure that all instances of mgetty are updated to versions that properly implement secure temporary file creation mechanisms, typically involving the use of secure file creation functions that prevent overwriting existing files or using unique temporary file names that cannot be predicted or manipulated by attackers. The vulnerability aligns with CWE-377 which addresses insecure temporary files and CWE-378 which covers creation of temporary files with insecure permissions. From an attack mitigation perspective, implementing proper file system permissions, using chroot jails for getty processes, and regularly auditing system configurations can significantly reduce the risk of exploitation. Additionally, monitoring for suspicious file creation patterns and implementing proper access controls for directories where temporary files might be created can provide additional layers of defense against this type of attack.