CVE-2023-28452
📋 TL;DR
CVE-2023-28452 is a DNS resolver vulnerability in CoreDNS that allows attackers to cause denial of service by sending forged DNS responses that cause the resolver to ignore legitimate responses. This affects all CoreDNS deployments using the default configuration for DNS resolution. The vulnerability allows attackers to disrupt DNS resolution without needing to guess transaction IDs.
💻 Affected Systems
- CoreDNS
📦 What is this software?
Coredns by Coredns.io
⚠️ Risk & Real-World Impact
Worst Case
Complete DNS resolution failure for affected CoreDNS instances, disrupting all dependent services that rely on DNS lookups through the vulnerable resolver.
Likely Case
Intermittent DNS resolution failures causing service disruptions, timeouts, and degraded application performance for systems relying on the vulnerable CoreDNS instance.
If Mitigated
Minimal impact if patched or workarounds implemented; some performance degradation possible under attack but DNS resolution continues.
🎯 Exploit Status
Exploit requires network access to the CoreDNS resolver and ability to send forged DNS responses. No authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: CoreDNS 1.10.2 and later
Vendor Advisory: https://coredns.io/
Restart Required: Yes
Instructions:
1. Download CoreDNS 1.10.2 or later from https://coredns.io/ 2. Replace existing CoreDNS binary with patched version 3. Restart CoreDNS service 4. Verify version with 'coredns -version'
🔧 Temporary Workarounds
Disable Recursive Resolution
allConfigure CoreDNS to forward all queries to upstream resolvers instead of performing recursive resolution
Modify Corefile to use forward plugin instead of default resolver
Network Segmentation
linuxRestrict network access to CoreDNS resolver ports (typically UDP/TCP 53) to trusted sources only
iptables -A INPUT -p udp --dport 53 -s trusted_network -j ACCEPT
iptables -A INPUT -p udp --dport 53 -j DROP
🧯 If You Can't Patch
- Implement network ACLs to restrict DNS traffic to trusted sources only
- Deploy redundant DNS resolvers and load balance between them to mitigate single point of failure
🔍 How to Verify
Check if Vulnerable:
Check CoreDNS version with 'coredns -version' or examine running process. If version is 1.10.1 or earlier, system is vulnerable.Check Version:
coredns -versionVerify Fix Applied:
Verify CoreDNS version is 1.10.2 or later with 'coredns -version'. Test DNS resolution functionality after patch.📡 Detection & Monitoring
Log Indicators:
- Increased DNS query timeouts
- Spike in DNS resolution failures
- Unusual source IPs sending DNS responses
Network Indicators:
- Unusual DNS response patterns
- DNS queries from legitimate clients receiving no response
- DNS traffic from unexpected sources
SIEM Query:
source="coredns" AND ("timeout" OR "failed" OR "no response")