CVE-2023-4408
📋 TL;DR
CVE-2023-4408 is a denial-of-service vulnerability in BIND's DNS message parsing code where crafted queries cause excessive CPU consumption due to algorithmic complexity issues. This affects both authoritative DNS servers and recursive resolvers running vulnerable BIND versions. Attackers can degrade DNS service performance or cause complete unavailability.
💻 Affected Systems
- ISC BIND
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Ontap by Netapp
Ontap by Netapp
⚠️ Risk & Real-World Impact
Worst Case
Complete DNS service outage due to 100% CPU exhaustion, disrupting all DNS resolution for dependent systems and services.
Likely Case
Degraded DNS performance causing increased query latency, timeouts, and intermittent service disruptions.
If Mitigated
Minimal impact with proper rate limiting, query filtering, and monitoring in place to detect and block attack traffic.
🎯 Exploit Status
Exploitation requires sending crafted DNS queries to vulnerable servers, which is straightforward for attackers with network access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 9.16.46, 9.18.22, 9.19.20, 9.11.37-S2, 9.16.45-S2, 9.18.21-S2
Vendor Advisory: https://kb.isc.org/docs/cve-2023-4408
Restart Required: Yes
Instructions:
1. Check current BIND version with 'named -v'. 2. Download patched version from ISC or your distribution's repository. 3. Stop BIND service. 4. Install updated package. 5. Restart BIND service. 6. Verify version is patched.
🔧 Temporary Workarounds
Rate Limiting
allImplement query rate limiting to reduce impact of attack traffic
# In named.conf: rate-limit { responses-per-second 10; };
Response Policy Zones (RPZ)
allUse RPZ to block queries from suspicious sources
# In named.conf: response-policy { zone "rpz"; };
🧯 If You Can't Patch
- Implement aggressive rate limiting and query filtering
- Deploy network-level protections (firewalls, IPS) to detect and block attack patterns
🔍 How to Verify
Check if Vulnerable:
Run 'named -v' and check if version falls within affected rangesCheck Version:
named -vVerify Fix Applied:
Confirm version is 9.16.46+, 9.18.22+, 9.19.20+, or corresponding -S2 versions📡 Detection & Monitoring
Log Indicators:
- Unusual CPU spikes in system logs
- Increased query processing time in BIND logs
- Query timeouts and failures
Network Indicators:
- Unusual DNS query patterns
- High volume of malformed queries
- Spike in DNS traffic from single sources
SIEM Query:
source="bind" AND (cpu_usage>90 OR query_time>5000)🔗 References
- http://www.openwall.com/lists/oss-security/2024/02/13/1
- https://kb.isc.org/docs/cve-2023-4408
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/HVRDSJVZKMCXKKPP6PNR62T7RWZ3YSDZ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PNNHZSZPG2E7NBMBNYPGHCFI4V4XRWNQ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RGS7JN6FZXUSTC2XKQHH27574XOULYYJ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZDZFMEKQTZ4L7RY46FCENWFB5MDT263R/
- https://security.netapp.com/advisory/ntap-20240426-0001/
- http://www.openwall.com/lists/oss-security/2024/02/13/1
- https://kb.isc.org/docs/cve-2023-4408
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/HVRDSJVZKMCXKKPP6PNR62T7RWZ3YSDZ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PNNHZSZPG2E7NBMBNYPGHCFI4V4XRWNQ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RGS7JN6FZXUSTC2XKQHH27574XOULYYJ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZDZFMEKQTZ4L7RY46FCENWFB5MDT263R/
- https://security.netapp.com/advisory/ntap-20240426-0001/
