CVE-2011-4191 in NetWare
Summary
by MITRE
Stack-based buffer overflow in the xdrDecodeString function in XNFS.NLM in Novell NetWare 6.5 SP8 allows remote attackers to execute arbitrary code or cause a denial of service (abend or NFS outage) via long packets.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/21/2024
The vulnerability identified as CVE-2011-4191 represents a critical stack-based buffer overflow flaw within the Network File System implementation of Novell NetWare 6.5 Service Pack 8. This issue specifically affects the xdrDecodeString function located within the XNFS.NLM module, which serves as the core component responsible for decoding network data representations in the NFS protocol stack. The flaw arises from insufficient input validation and bounds checking when processing incoming network packets, creating an exploitable condition that can be leveraged by remote attackers to gain unauthorized system access or disrupt service availability.
The technical implementation of this vulnerability stems from improper handling of string data structures during network packet processing. When the xdrDecodeString function receives malformed or excessively long string data, it fails to validate the length constraints before copying data into fixed-size stack buffers. This classic buffer overflow condition allows attackers to overwrite adjacent stack memory locations, potentially corrupting program execution flow and enabling arbitrary code execution. The vulnerability operates at the network protocol level, making it particularly dangerous as it can be exploited remotely without requiring local system access or authentication credentials. The flaw specifically targets the Network File System implementation where the XNFS.NLM module handles network communication for file sharing operations.
The operational impact of this vulnerability extends beyond simple code execution to encompass both availability and integrity threats. Remote attackers can leverage this weakness to cause system abends or complete NFS service outages, effectively disrupting business operations and file sharing capabilities across the network. The potential for arbitrary code execution provides attackers with persistent access to affected systems, enabling them to escalate privileges, establish backdoors, or perform data exfiltration activities. Given that NetWare 6.5 SP8 was widely deployed in enterprise environments for file serving and network management, the exploitation of this vulnerability could result in significant operational disruption and security breaches affecting multiple organizational assets simultaneously.
Mitigation strategies for CVE-2011-4191 should focus on immediate patching of affected Novell NetWare systems with the vendor-provided security updates. Organizations must also implement network segmentation and access controls to limit exposure of vulnerable NFS services to untrusted networks. Network monitoring solutions should be configured to detect anomalous packet sizes and malformed network traffic patterns that may indicate exploitation attempts. Additionally, system administrators should consider disabling unnecessary NFS services and implementing intrusion detection systems to monitor for suspicious network activity. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow and represents a significant concern under the ATT&CK framework category of Execution and Persistence, specifically targeting remote code execution capabilities through network-based attacks. Organizations should also conduct thorough vulnerability assessments to identify other potentially affected systems and ensure comprehensive network security posture maintenance.