CVE-2007-0452 in Samba
Summary
by MITRE
smbd in Samba 3.0.6 through 3.0.23d allows remote authenticated users to cause a denial of service (memory and CPU exhaustion) by renaming a file in a way that prevents a request from being removed from the deferred open queue, which triggers an infinite loop.
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Analysis
by VulDB Data Team • 03/15/2021
The vulnerability described in CVE-2007-0452 affects the smbd daemon component within Samba versions 3.0.6 through 3.0.23d, representing a significant denial of service weakness that can be exploited by authenticated remote attackers. This flaw specifically targets the file renaming functionality within the Samba file sharing service, creating a condition where legitimate file operations can be manipulated to trigger system resource exhaustion. The vulnerability operates through a sophisticated mechanism involving the deferred open queue management system, which is a core component of Samba's file handling architecture designed to manage file access requests that cannot be immediately processed.
The technical implementation of this vulnerability stems from improper handling of file rename operations that affect the deferred open queue structure. When an authenticated user performs a specific sequence of file renaming operations, the system fails to properly remove the affected file request from the deferred open queue, causing the queue to become stuck in an infinite loop. This condition occurs because the rename operation creates a circular dependency within the internal queue management system, where the system continuously attempts to process the same request without ever completing the operation. The flaw resides in the lack of proper queue state validation and cleanup mechanisms during file rename operations, which violates standard software engineering practices for resource management and queue handling.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise system availability and performance across networked environments. Remote authenticated users can exploit this weakness to consume excessive system resources through memory allocation and cpu processing cycles, effectively creating a denial of service condition that can impact legitimate users and services relying on the affected Samba server. The infinite loop mechanism causes continuous resource consumption without proper termination conditions, leading to progressive system degradation and potential complete service unavailability. This vulnerability particularly affects enterprise environments where Samba servers serve as critical file sharing infrastructure, as it can be exploited by attackers who have gained legitimate authentication credentials to the system.
Security practitioners should recognize this vulnerability as a classic example of resource exhaustion attack patterns that align with attack techniques documented in the attack tree framework, specifically relating to service disruption and availability compromise. The vulnerability also corresponds to CWE-400, which categorizes "Uncontrolled Resource Consumption" as a fundamental weakness in software design that leads to denial of service conditions. Organizations should implement immediate mitigation strategies including patching affected Samba versions to 3.0.24 or later, where the fix addresses the queue management logic and proper cleanup of deferred open requests. Additionally, network segmentation and access controls should be enforced to limit authentication privileges to only necessary users, reducing the attack surface for potential exploitation. Monitoring systems should be configured to detect unusual resource consumption patterns and abnormal file operation sequences that may indicate exploitation attempts. The remediation process should also include implementing proper queue timeout mechanisms and validation checks to prevent similar issues in future software releases.