Source: cve@mitre.org
Windows NT 4.0 and Windows 2000 hosts allow remote attackers to cause a denial of service (unavailable connections) by sending multiple SMB SMBnegprots requests but not reading the response that is sent back.
Windows NT 4.0 and Windows 2000 servers are vulnerable to a denial-of-service (DoS) attack. Attackers can remotely exhaust server resources by sending a flood of malformed SMB requests, leading to service unavailability and potential business disruption.
Step 1: Request Flood: The attacker sends a large number of SMBnegprot requests to the target server over port 139 or 445 (SMB ports). These requests initiate the SMB connection process.
The vulnerability stems from a flaw in how the SMB service handles connection establishment. Specifically, the server allocates resources (e.g., connection slots, memory) for each incoming SMBnegprot request, but doesn't properly track or reclaim these resources if the client doesn't complete the connection handshake by reading the response. By sending a large number of these requests without reading the responses, an attacker can exhaust the server's available resources, leading to a DoS condition. The root cause is a lack of proper resource management and connection tracking, leading to resource exhaustion. This is not a buffer overflow or memory corruption vulnerability, but rather a resource exhaustion issue.
While no specific APTs are directly associated with this specific CVE due to its age, the attack vector (DoS via resource exhaustion) is a common tactic. The vulnerability is not listed in the CISA KEV catalog due to its age and the fact that the affected OSes are out of support.
Network traffic analysis: Monitor for a high volume of SMBnegprot requests from a single source IP address, especially if the responses are not being acknowledged.
Log analysis: Examine SMB server logs for a large number of connection attempts that are not followed by subsequent SMB operations.
Performance monitoring: Observe server resource utilization (CPU, memory, network bandwidth). A sudden spike in resource usage could indicate an ongoing attack.
Intrusion Detection Systems (IDS): Implement IDS rules to detect anomalous SMB traffic patterns, such as a flood of SMBnegprot requests.
Upgrade: The primary remediation is to migrate from Windows NT 4.0 and Windows 2000 to a supported operating system. These operating systems are no longer supported and receive no security updates.
Network Segmentation: Isolate legacy systems from the rest of the network to limit the attack surface.
Firewall Rules: Implement firewall rules to restrict SMB traffic to only trusted sources.
Intrusion Prevention Systems (IPS): Deploy an IPS to detect and block malicious SMB traffic patterns.
Monitor Network Traffic: Continuously monitor network traffic for suspicious activity, including a high volume of SMBnegprot requests.