CVE-2003-0877 in Mac OS X
Summary
by MITRE
Mac OS X before 10.3 with core files enabled allows local users to overwrite arbitrary files and read core files via a symlink attack on core files that are created with predictable names in the /cores directory.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 05/04/2019
This vulnerability exists in Mac OS X versions prior to 10.3 where core file generation is enabled by default. The flaw stems from the predictable naming convention used for core files created in the /cores directory, which creates a significant security risk for local users who can exploit this weakness through symbolic link manipulation. The vulnerability is classified under CWE-59 as improper link resolution without maximum scalar limit, specifically targeting the core dump file system. Attackers can leverage this issue by creating symbolic links in the /cores directory that point to sensitive system files, allowing them to overwrite critical files or read core dumps that would normally be restricted. The predictable naming scheme means that attackers can accurately guess the core file names before they are created, enabling them to establish malicious symlinks that will be followed when the core file is generated. This type of attack is particularly dangerous because it can be executed by any local user who has access to the system, potentially leading to privilege escalation or data corruption. The vulnerability demonstrates a classic race condition problem where the timing between symlink creation and core file generation can be exploited to redirect file operations to unintended targets.
The operational impact of this vulnerability extends beyond simple file overwrites as it can be used to compromise system integrity and confidentiality. Local attackers can use this technique to read core files that may contain sensitive information such as memory dumps of running processes, potentially exposing passwords, encryption keys, or other confidential data. The attack vector specifically targets the /cores directory which is typically world-writable in default Mac OS X installations, making it an easy target for exploitation. This vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1566.001 for credential access through exploitation of system vulnerabilities. The issue is particularly concerning in multi-user environments where less privileged users might attempt to exploit this weakness to gain elevated privileges or access restricted resources. The predictable naming convention used by the core file system creates a window of opportunity for attackers to manipulate the file system before the core dump is actually written to disk, effectively allowing for arbitrary file modification or reading.
Mitigation strategies for this vulnerability should focus on both immediate system hardening and long-term security improvements. System administrators should disable core file generation if it is not required for debugging purposes, which can be accomplished through the use of ulimit commands or system configuration changes. The /cores directory permissions should be reviewed and restricted to prevent unauthorized symlink creation, ensuring that only authorized users or processes can modify the directory contents. Additionally, implementing proper file system monitoring and access controls can help detect and prevent symlink attacks before they are successfully executed. The recommended approach involves changing the core file naming scheme to be less predictable, using timestamps or random identifiers instead of simple predictable patterns. Security patches for Mac OS X 10.3 and later versions address this vulnerability by implementing proper symlink handling and randomizing core file names to prevent predictable attack vectors. Organizations should also consider implementing automated monitoring systems that can detect suspicious symlink creation patterns in the /cores directory, as this type of attack is often a precursor to more sophisticated exploitation attempts. Regular security audits should verify that core file generation is properly configured and that no unnecessary access permissions exist on the core dump directories.