CVE-2003-0440 in MIME Library
Summary
by MITRE
The (1) semi MIME library 1.14.5 and earlier, and (2) wemi 1.14.0 and possibly other versions, allows local users to overwrite arbitrary files via a symlink attack on temporary files.
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Analysis
by VulDB Data Team • 06/29/2021
The vulnerability described in CVE-2003-0440 represents a critical security flaw in email processing libraries that affects both the semi MIME library version 1.14.5 and earlier, as well as the wemi library version 1.14.0 and potentially other related versions. This issue stems from improper handling of temporary files during email processing operations, creating a dangerous race condition that can be exploited by local attackers to overwrite arbitrary files on the system. The vulnerability operates through a symlink attack mechanism where an attacker can manipulate the temporary file creation process to redirect file operations to locations of their choosing.
The technical implementation of this flaw involves the libraries creating temporary files without proper security checks or atomic operations. When these libraries process email messages, they generate temporary files to store intermediate data during MIME parsing operations. The vulnerability occurs because the libraries do not validate whether the temporary file path already exists as a symbolic link, nor do they implement proper file creation atomicity measures. This allows a local attacker to pre-create symbolic links with the same names that the library will attempt to create, effectively redirecting the library's file operations to arbitrary locations on the filesystem.
From an operational impact perspective, this vulnerability enables local privilege escalation and arbitrary file overwrite attacks that can have severe consequences for system integrity and confidentiality. An attacker with local access can potentially overwrite critical system files, configuration files, or even files belonging to other users, depending on the privileges of the process running the vulnerable library. The attack requires local system access but does not need network connectivity, making it particularly dangerous in environments where local access is not properly restricted. The vulnerability can be exploited to corrupt system files, install malicious code, or escalate privileges to higher-level accounts.
The attack vector for this vulnerability aligns with common exploitation patterns documented in the MITRE ATT&CK framework under the technique of privilege escalation through file system manipulation. This weakness maps directly to CWE-377: Insecure Temporary File and CWE-378: Creation of Temporary File With Insecure Permissions, both of which are categorized under insecure system configuration and improper file handling. The vulnerability demonstrates poor secure coding practices where temporary file creation does not follow security best practices such as using secure temporary file creation functions, implementing proper file permissions, or ensuring atomic file operations. Organizations should implement immediate mitigations including upgrading to patched versions of the affected libraries, implementing proper file system permissions, and conducting security audits to identify other instances of similar vulnerabilities in their software stack.