CVE-2003-0501 in Linux
Summary
by MITRE
The /proc filesystem in Linux allows local users to obtain sensitive information by opening various entries in /proc/self before executing a setuid program, which causes the program to fail to change the ownership and permissions of those entries.
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Analysis
by VulDB Data Team • 11/03/2024
The vulnerability described in CVE-2003-0501 represents a significant information disclosure issue within the Linux kernel's handling of the /proc filesystem. This flaw specifically affects the way the kernel manages file permissions and ownership when setuid programs are executed, creating a window of opportunity for local attackers to access sensitive system information that should normally be restricted to privileged users.
The technical mechanism behind this vulnerability involves the /proc filesystem's behavior during process execution. When a setuid program is executed, the kernel typically resets the ownership and permissions of various /proc entries to prevent unauthorized access to sensitive process information. However, in this case, if an attacker opens specific entries in /proc/self before executing a setuid program, those entries retain their original permissions and ownership settings. This creates a race condition where the attacker can access information about the process that would normally be protected by proper privilege separation.
This vulnerability directly relates to CWE-200, which addresses "Information Exposure," and aligns with ATT&CK technique T1082, "System Information Discovery," as it enables attackers to gather system information through improper access controls. The flaw essentially allows local users to bypass normal privilege boundaries that should prevent access to process-specific information such as memory mappings, file descriptors, and other sensitive process data that is typically only accessible to the process owner or root.
The operational impact of this vulnerability extends beyond simple information disclosure, as the leaked information can provide attackers with valuable insights for further exploitation. Process information obtained through this vulnerability may include memory addresses, file descriptor numbers, and other data that could be used to craft more sophisticated attacks such as buffer overflows or privilege escalation attempts. The vulnerability is particularly concerning because it requires no special privileges to exploit, making it accessible to any local user on the system.
Mitigation strategies for this vulnerability should focus on proper kernel patching and system hardening. The primary fix involves ensuring that the kernel properly resets file permissions and ownership of /proc entries when setuid programs are executed. System administrators should apply the appropriate kernel security patches and regularly update their systems to address this class of vulnerabilities. Additionally, implementing proper process isolation and monitoring for unusual access patterns to /proc filesystem entries can help detect potential exploitation attempts. Security frameworks such as SELinux or AppArmor can also provide additional protection layers by enforcing mandatory access controls that complement the kernel's inherent protections. Organizations should also consider implementing least privilege principles and regularly auditing system configurations to minimize the attack surface and reduce the potential impact of such information disclosure vulnerabilities.