CVE-2007-0393 in Solaris
Summary
by MITRE
Sun Solaris 9 does not properly verify the status of file descriptors before setuid execution, which allows local users to gain privileges by closing file descriptor 0, 1, or 2 and then invoking a setuid program, a variant of CVE-2002-0572.
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Analysis
by VulDB Data Team • 08/17/2018
The vulnerability described in CVE-2007-0393 represents a critical privilege escalation flaw in Sun Solaris 9 operating systems that stems from improper file descriptor validation during setuid execution. This issue is particularly significant because it allows local attackers to elevate their privileges through a relatively simple manipulation of standard input/output streams. The flaw specifically targets the kernel's handling of file descriptors when executing setuid programs, creating a pathway for unauthorized privilege escalation that directly violates fundamental security principles of Unix-like systems.
The technical root cause of this vulnerability lies in the improper verification of file descriptor states before executing setuid operations. When a setuid program is invoked, the system should ensure that all file descriptors are properly initialized and validated to prevent potential manipulation. However, Solaris 9 fails to adequately check the status of file descriptors 0, 1, and 2, which correspond to standard input, output, and error streams respectively. This oversight creates a window of opportunity where a malicious user can close these critical file descriptors and subsequently invoke setuid programs that will then execute with elevated privileges, as the system fails to properly validate the security context before proceeding with privilege escalation.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it represents a fundamental breakdown in the security model of the operating system. Attackers can exploit this weakness to execute arbitrary code with elevated privileges, potentially compromising the entire system. The vulnerability operates at the kernel level and affects all setuid programs on the system, making it particularly dangerous as it can be leveraged to gain access to sensitive system resources, modify critical files, or establish persistent backdoors. This flaw aligns with CWE-276, which addresses improper privilege management, and demonstrates how inadequate file descriptor handling can lead to serious security breaches in operating system kernels.
This vulnerability also relates to the broader category of privilege escalation techniques documented in the ATT&CK framework under privilege escalation tactics. The specific method of closing standard file descriptors before invoking setuid programs represents a well-known exploitation pattern that has been documented in various security research publications. The attack vector is particularly concerning because it requires minimal privileges to execute and can be automated, making it a preferred technique for attackers seeking to establish persistent access to compromised systems. The vulnerability's relationship to CVE-2002-0572 indicates that this is part of a broader class of issues affecting Unix-like systems where improper file descriptor validation leads to privilege escalation opportunities, and the fact that it was present in Solaris 9 demonstrates the longevity of such fundamental security flaws in enterprise operating systems.
The mitigation strategies for CVE-2007-0393 focus on both immediate system hardening and long-term architectural improvements. System administrators should ensure that all Solaris 9 systems are patched with the appropriate security updates from Sun Microsystems, which would address the underlying file descriptor validation issue. Additionally, implementing proper access controls, monitoring for suspicious file descriptor manipulation, and conducting regular security audits can help detect and prevent exploitation attempts. The vulnerability highlights the importance of proper input validation and security context verification in kernel-level operations, and serves as a reminder that even fundamental system components require rigorous security testing and validation to prevent such critical flaws from persisting in production environments. Organizations should also consider implementing additional security measures such as mandatory access controls and privilege separation mechanisms to reduce the potential impact of similar vulnerabilities in the future.