CVE-2017-1000382 in VIM
Summary
by MITRE
VIM version 8.0.1187 (and other versions most likely) ignores umask when creating a swap file ("[ORIGINAL_FILENAME].swp") resulting in files that may be world readable or otherwise accessible in ways not intended by the user running the vi binary.
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Analysis
by VulDB Data Team • 12/02/2019
The vulnerability identified as CVE-2017-1000382 affects the vi/vim text editor across multiple versions including 8.0.1187 where the software fails to properly respect the umask setting when creating swap files. This flaw represents a significant security concern as it allows unauthorized access to sensitive data that users might be editing through the vim editor. The swap file created by vim typically bears the name "[ORIGINAL_FILENAME].swp" and serves as a temporary backup mechanism during editing sessions. When vim ignores the umask setting, it creates these swap files with overly permissive access permissions that may inadvertently expose confidential information to other users on the same system.
This vulnerability directly relates to CWE-276, which describes improper file permissions, and falls under the broader category of inadequate access control mechanisms. The operational impact of this flaw extends beyond simple information disclosure as it can lead to data leakage in multi-user environments where different users share the same system resources. When vim creates swap files without properly applying the umask, these files may be created with world-readable permissions, allowing any user on the system to potentially access the contents of the swap file. This creates a scenario where sensitive information such as passwords, personal data, or proprietary documents could be exposed through the swap file mechanism.
The security implications are particularly severe in shared hosting environments, enterprise systems, or any multi-user scenario where users may not trust each other or where compliance requirements mandate strict data isolation. Attackers could exploit this vulnerability by monitoring system directories for swap files and then examining their contents to extract sensitive information. The vulnerability also aligns with ATT&CK technique T1005, which covers data from local system, as it enables unauthorized access to data stored in temporary files. Additionally, this issue can be leveraged in conjunction with other techniques to escalate privileges or gather intelligence about system users.
The recommended mitigations include updating to vim versions that properly respect umask settings, typically versions released after the vulnerability was patched. System administrators should also implement monitoring for swap files and ensure that proper file permissions are enforced through system-level controls. Regular security audits should verify that swap files are not created with excessive permissions, and organizations should consider implementing automated scanning tools to detect and alert on improperly secured temporary files. The vulnerability demonstrates the critical importance of proper privilege management and access control enforcement in system utilities, particularly those that handle sensitive user data in temporary storage mechanisms.