CVE-2003-1073 in Solaris
Summary
by MITRE
A race condition in the at command for Solaris 2.6 through 9 allows local users to delete arbitrary files via the -r argument with .. (dot dot) sequences in the job name, then modifying the directory structure after at checks permissions to delete the file and before the deletion actually takes place.
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Analysis
by VulDB Data Team • 01/22/2025
The vulnerability described in CVE-2003-1073 represents a critical race condition flaw in the at command implementation across Solaris versions 2.6 through 9. This race condition occurs during the file deletion process when the at command processes job names containing .. (dot dot) sequences through the -r argument. The fundamental issue lies in the timing window between permission checks and actual file deletion operations, creating an exploitable gap that malicious users can manipulate for unauthorized file removal.
The technical execution of this vulnerability involves a sophisticated attack pattern that leverages the inherent timing discrepancy in the at command's file handling mechanism. When a user specifies a job name containing .. sequences through the -r argument, the system first validates permissions and then proceeds with the deletion process. However, this validation occurs before the actual file operations commence, leaving a window where an attacker can modify the directory structure between the permission check and the actual deletion. The race condition specifically exploits the fact that the at command does not maintain consistent file state checks throughout the deletion sequence, allowing for arbitrary file removal through manipulation of the filesystem hierarchy.
From an operational impact perspective, this vulnerability poses significant security risks to Solaris systems, particularly in environments where multiple users share system resources. The local privilege escalation potential allows attackers to delete files that they would normally not have permission to access, effectively bypassing normal file system security controls. This vulnerability can be particularly dangerous when combined with other attack vectors, as it enables attackers to remove critical system files, logs, or configuration data that could compromise system integrity and availability. The exploitability is enhanced by the fact that it requires minimal privileges and can be executed by any local user, making it a particularly concerning weakness in the operating system's security model.
The vulnerability aligns with CWE-367, which specifically addresses time-of-check to time-of-use (TOCTOU) race conditions, where the state of a resource changes between the time it is checked and when it is used. This classification highlights the fundamental flaw in the system's design where it performs a permission check and then proceeds with operations without revalidating the resource state. Additionally, the attack pattern relates to techniques described in the MITRE ATT&CK framework under privilege escalation and defense evasion tactics, where attackers exploit system implementation weaknesses to gain unauthorized access to resources. Organizations running affected Solaris versions should implement immediate mitigations including patching the at command, restricting local user access to at functionality, and monitoring for suspicious at job creation patterns that might indicate exploitation attempts.
The root cause of this vulnerability demonstrates poor input validation and insufficient resource state management within the at command implementation. The system fails to maintain atomic operations between permission validation and file deletion, creating an exploitable window where attackers can manipulate the underlying filesystem structure. This flaw represents a classic example of how seemingly simple command line utilities can contain complex security vulnerabilities when proper synchronization mechanisms are not implemented. The vulnerability's persistence across multiple Solaris versions indicates a systemic issue in the operating system's approach to handling file operations and privilege management, requiring comprehensive system-level remediation rather than isolated patching.