Source: cve@mitre.org
The Windows Internet Naming Service (WINS) in Windows NT Server 4.0 SP 6a, NT Terminal Server 4.0 SP 6, Windows 2000 Server SP3 and SP4, and Windows Server 2003 does not properly validate the computer name value in a WINS packet, which allows remote attackers to execute arbitrary code or cause a denial of service (server crash), which results in an "unchecked buffer" and possibly triggers a buffer overflow, aka the "Name Validation Vulnerability."
Critical vulnerability in Windows Internet Naming Service (WINS) allows remote attackers to execute arbitrary code or cause a denial of service. This flaw, stemming from improper validation of computer names in WINS packets, can lead to a server crash or remote code execution, posing a significant risk to affected systems.
Step 1: Packet Crafting: An attacker crafts a malicious WINS packet. This packet contains a specially crafted computer name field.
Step 2: Name Length Manipulation: The attacker sets the computer name field to a length that exceeds the allocated buffer size within the WINS service.
Step 3: Packet Transmission: The attacker sends the malicious WINS packet to the vulnerable WINS server.
Step 4: Packet Reception & Processing: The WINS server receives the packet and attempts to process it.
Step 5: Buffer Overflow Trigger: Due to the lack of proper input validation, the WINS service copies the oversized computer name into a fixed-size buffer without checking the length. This overwrites adjacent memory locations, leading to a buffer overflow.
Step 6: Exploitation (RCE or DoS): Depending on the overwritten memory, the attacker can achieve either remote code execution (RCE) by overwriting code pointers or cause a denial-of-service (DoS) by corrupting critical data structures, leading to a server crash.
The vulnerability lies in the WINS service's failure to properly validate the length and content of the computer name field within incoming WINS packets. Specifically, the service doesn't adequately check the size of the provided name before copying it into a fixed-size buffer. This leads to an unchecked buffer condition, which can be exploited to trigger a buffer overflow. By crafting a malicious WINS packet with an overly long computer name, an attacker can overwrite adjacent memory regions, potentially overwriting critical data structures or injecting malicious code. The root cause is a lack of input validation and bounds checking on the computer name field during packet processing within the WINS service's internal logic. This allows for the overwrite of memory, leading to either a crash (denial of service) or the execution of arbitrary code.
This vulnerability could be leveraged by various threat actors targeting legacy systems. While no specific APTs are directly linked, any actor with the capability to identify and exploit vulnerabilities could utilize this. The age of the vulnerability makes it less attractive for widespread use, but it could be used in targeted attacks. This vulnerability is not listed on the CISA KEV.
Network traffic analysis: Examine network traffic for WINS packets with unusually long computer name fields.
IDS/IPS signatures: Implement signatures to detect malicious WINS packets based on known exploit patterns.
Log analysis: Review WINS server logs for errors, crashes, or unusual activity related to name registration or resolution.
Memory forensics: Analyze memory dumps of the WINS server for signs of buffer overflows or corrupted data structures after a suspected attack.
Patching: Apply the security patches provided by Microsoft for the affected operating systems. This is the primary and most effective remediation step.
Network Segmentation: Isolate WINS servers from the public internet and limit network access to only trusted clients.
Disable WINS (if possible): If WINS is not required, disable the service to eliminate the attack surface. Consider using DNS instead.
Regular Security Audits: Conduct regular security audits and vulnerability scans to identify and address potential weaknesses.
Implement Host-Based Intrusion Detection: Deploy host-based intrusion detection systems (HIDS) to monitor for suspicious activity on WINS servers.
Update Antivirus/Endpoint Detection and Response (EDR) solutions: Ensure that antivirus and EDR solutions are up-to-date to detect and prevent exploitation attempts.