CVE-2014-0244 in Samba
Summary
by MITRE
The sys_recvfrom function in nmbd in Samba 3.6.x before 3.6.24, 4.0.x before 4.0.19, and 4.1.x before 4.1.9 allows remote attackers to cause a denial of service (infinite loop and CPU consumption) via a malformed UDP packet.
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Analysis
by VulDB Data Team • 08/01/2021
The vulnerability identified as CVE-2014-0244 represents a critical denial of service flaw affecting the Samba file sharing implementation. This issue specifically targets the nmbd daemon which handles NetBIOS name service operations within Samba environments. The vulnerability manifests in Samba versions 3.6.x prior to 3.6.24, 4.0.x prior to 4.0.19, and 4.1.x prior to 4.1.9, creating a persistent security risk for organizations relying on these older Samba implementations. The flaw exists within the sys_recvfrom function which processes incoming UDP packets, making it particularly dangerous as it can be exploited through standard network traffic without requiring authentication or elevated privileges.
The technical nature of this vulnerability stems from inadequate input validation within the UDP packet processing mechanism. When nmbd receives a malformed UDP packet, the sys_recvfrom function fails to properly handle the malformed data structure, leading to an infinite loop condition in the packet processing code. This infinite loop consumes excessive CPU resources, effectively causing a denial of service condition that can render the affected Samba service unavailable to legitimate users. The vulnerability operates at the network protocol level, exploiting weaknesses in how the system handles malformed network traffic, which aligns with CWE-129 Input Validation and CWE-691 Insufficient Control Flow Management. The flaw demonstrates a classic control flow management issue where improper error handling leads to resource exhaustion rather than graceful degradation.
The operational impact of CVE-2014-0244 extends beyond simple service disruption, creating potential business continuity risks for organizations that depend on Samba services for file sharing and network resource access. When exploited, the vulnerability can cause sustained high CPU utilization, potentially leading to system instability, performance degradation, and complete service unavailability. Network administrators may experience difficulty in identifying the source of the issue since the attack appears as normal network traffic, making detection and mitigation more challenging. The vulnerability affects systems running older Samba versions that are still in production use, particularly in enterprise environments where software updates may be delayed due to compatibility concerns or change management processes. This creates a persistent risk vector that can be exploited by attackers to disrupt critical network services.
Organizations should prioritize immediate patching of affected Samba installations to address this vulnerability. The recommended mitigation involves upgrading to Samba versions 3.6.24, 4.0.19, or 4.1.9 respectively, which contain the necessary code fixes to properly validate incoming UDP packets and prevent the infinite loop condition. Network segmentation and firewall rules can provide temporary protection by limiting UDP traffic to necessary ports, though this approach does not eliminate the underlying vulnerability. Monitoring systems should be enhanced to detect unusual CPU consumption patterns in nmbd processes, which could indicate exploitation attempts. Additionally, implementing intrusion detection systems with signature-based detection for malformed UDP packets can help identify potential exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date software implementations and demonstrates how seemingly minor input validation flaws can lead to significant operational disruptions. This issue aligns with ATT&CK technique T1499.004 for network denial of service and emphasizes the need for robust network protocol handling within service implementations.