CVE-2012-0817 in smbd
Summary
by MITRE
Memory leak in smbd in Samba 3.6.x before 3.6.3 allows remote attackers to cause a denial of service (memory and CPU consumption) by making many connection requests.
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Analysis
by VulDB Data Team • 03/20/2021
The vulnerability identified as CVE-2012-0817 represents a critical memory management flaw within the Samba file sharing implementation that affects versions 3.6.x prior to 3.6.3. This issue specifically targets the smbd daemon which serves as the primary SMB/CIFS server component in Samba installations. The memory leak occurs during the processing of multiple concurrent connection requests, creating a condition where allocated memory is not properly released back to the system. This flaw enables remote attackers to exploit the service by establishing numerous connection attempts in rapid succession, leading to progressive memory exhaustion and subsequent system instability.
The technical nature of this vulnerability aligns with CWE-401, which classifies memory leaks as a common weakness in software systems. The flaw manifests when the smbd process handles incoming connection requests without properly managing memory allocation for connection contexts and associated data structures. Each connection attempt consumes memory resources that should be freed upon connection termination or failure, but due to the programming error in the memory management routines, these resources remain allocated indefinitely. This behavior creates a gradual degradation of system performance as memory consumption increases linearly with each successive connection attempt.
From an operational impact perspective, this vulnerability presents a significant threat to network services relying on Samba for file sharing operations. The denial of service condition can be easily exploited by any remote attacker with network access to the affected system, requiring minimal resources to execute the attack. The memory consumption grows steadily with each connection attempt, eventually exhausting available system memory and causing the smbd service to become unresponsive or crash entirely. CPU utilization also increases significantly as the system struggles to process connection requests while memory resources dwindle, creating a cascading effect that impacts overall system performance and availability.
The attack vector for CVE-2012-0817 follows the patterns described in the MITRE ATT&CK framework under the Tactic of Resource Exhaustion and Denial of Service. Attackers can leverage this vulnerability through network-based exploitation without requiring authentication or specialized privileges, making it particularly dangerous in enterprise environments where Samba services are commonly exposed to external networks. The exploitability of this flaw is enhanced by the fact that it can be triggered through legitimate SMB connection protocols, making detection difficult and the attack indistinguishable from normal network traffic. Organizations using Samba versions within the affected range face substantial risk of service disruption and potential data access denial that could impact business operations and user productivity.
Mitigation strategies for this vulnerability should prioritize immediate patch application to Samba versions 3.6.3 and later, which contain the necessary memory management fixes. System administrators should also implement connection rate limiting and monitoring mechanisms to detect unusual connection patterns that may indicate exploitation attempts. Network segmentation and firewall rules can help limit exposure by restricting access to Samba services to trusted networks only. Additionally, implementing memory monitoring and alerting systems can help detect the onset of memory exhaustion conditions before complete service failure occurs, providing early warning of potential exploitation attempts.