CVE-1999-0730 in Linux
Summary
by MITRE
The zsoelim program in the Debian man-db package allows local users to overwrite files via a symlink attack.
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Analysis
by VulDB Data Team • 09/25/2024
The vulnerability identified as CVE-1999-0730 resides within the zsoelim program component of the Debian man-db package, representing a classic symlink attack scenario that has significant implications for local privilege escalation and file system integrity. This flaw specifically affects systems where the zsoelim utility is executed with elevated privileges or in contexts where user-controlled temporary files may be created and subsequently overwritten through symbolic link manipulation.
The technical implementation of this vulnerability stems from inadequate handling of temporary files within the zsoelim program. When the program processes compressed manual pages, it creates temporary files that are susceptible to symlink attacks. Local attackers can exploit this by creating symbolic links in the temporary directory that point to sensitive system files, causing the zsoelim utility to overwrite these target files with arbitrary content when it performs its normal operations. This represents a direct violation of proper file system access controls and demonstrates a lack of proper input validation and temporary file management practices.
The operational impact of this vulnerability extends beyond simple file overwrites, as it can potentially enable local users to modify critical system files, including configuration files, binaries, or other sensitive resources that the zsoelim program might have write permissions to access. Attackers could leverage this to escalate privileges, corrupt system integrity, or establish persistent access points within the affected systems. The vulnerability is particularly concerning because it operates at the local user level without requiring network access or complex exploitation techniques, making it readily available for exploitation in compromised environments.
Security practitioners should recognize this issue as a variant of the broader category of temporary file handling vulnerabilities that are commonly classified under CWE-377 and CWE-378, which address insecure temporary file creation and weak temporary file permissions respectively. The attack pattern aligns with several techniques documented in the MITRE ATT&CK framework under the T1059.007 sub-technique for "Command and Scripting Interpreter: PowerShell" and more broadly under T1068 for "Exploitation for Privilege Escalation" when considering the potential for privilege escalation through file system manipulation. The vulnerability also demonstrates characteristics of T1548.001 for "Abuse Elevation Control Mechanism: Setuid and Setgid" when the zsoelim program is executed with elevated privileges.
Mitigation strategies should focus on implementing proper temporary file handling practices, including the use of secure temporary file creation methods such as mkstemp or similar functions that ensure atomic creation of temporary files with appropriate permissions. System administrators should also consider implementing proper file system permissions and access controls, ensuring that the zsoelim program does not execute with unnecessary elevated privileges. Additionally, the Debian man-db package should be updated to versions that properly address this symlink attack vulnerability through either code fixes that prevent the creation of vulnerable temporary files or through proper validation of symbolic links before file operations. Regular security audits and privilege reviews should be conducted to identify and remediate similar vulnerabilities in other system components, particularly those handling temporary files or user input in potentially privileged contexts.