CVE-2023-30464
📋 TL;DR
This vulnerability in CoreDNS allows attackers to perform DNS cache poisoning attacks using a birthday attack technique. Attackers can inject fake DNS responses, potentially redirecting users to malicious websites. Any organization running vulnerable CoreDNS versions is affected.
💻 Affected Systems
- CoreDNS
📦 What is this software?
Coredns by Coredns.io
⚠️ Risk & Real-World Impact
Worst Case
Complete DNS cache poisoning leading to widespread traffic redirection to attacker-controlled infrastructure, enabling credential theft, malware distribution, or service disruption.
Likely Case
Targeted DNS cache poisoning affecting specific domains, potentially redirecting users to phishing sites or intercepting sensitive communications.
If Mitigated
Limited impact with proper network segmentation, DNS security extensions, and monitoring in place.
🎯 Exploit Status
Exploitation requires network access to the DNS server and understanding of birthday attack techniques against DNS.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.10.2 and later
Vendor Advisory: https://github.com/coredns/coredns/security/advisories/GHSA-5wvr-9jvp-8fpg
Restart Required: Yes
Instructions:
1. Update CoreDNS to version 1.10.2 or later. 2. Stop CoreDNS service. 3. Replace binary with patched version. 4. Restart CoreDNS service. 5. Verify functionality.
🔧 Temporary Workarounds
Enable DNS Security Extensions
allImplement DNSSEC to validate DNS responses and prevent cache poisoning
# Configure DNSSEC in CoreDNS configuration file
# Add 'dnssec' plugin to zones requiring validation
Reduce Cache TTL
allLower DNS cache time-to-live values to reduce window for poisoning attacks
# In Corefile, set lower TTL values for cache plugin
cache {
ttl 300
}
🧯 If You Can't Patch
- Implement network segmentation to restrict access to DNS servers
- Deploy intrusion detection systems to monitor for DNS poisoning attempts
🔍 How to Verify
Check if Vulnerable:
Check CoreDNS version with 'coredns -version' command. If version is 1.10.1 or earlier, system is vulnerable.Check Version:
coredns -versionVerify Fix Applied:
After patching, run 'coredns -version' to confirm version is 1.10.2 or later.📡 Detection & Monitoring
Log Indicators:
- Unusual DNS query patterns
- Multiple failed DNS responses from same source
- DNS responses with mismatched transaction IDs
Network Indicators:
- Unexpected DNS response traffic
- DNS queries with spoofed source IPs
- High volume of DNS queries to same domain
SIEM Query:
source="dns.log" | stats count by query, response_code | where count > threshold