Listen to this Post
Introduction:
The Domain Name System (DNS) is the phonebook of the internet, but without DNSSEC (DNS Security Extensions), it remains vulnerable to cache poisoning and spoofing attacks. Capita’s recent failure to secure the child zones of the Civil Service Pension Scheme (CSPS) – despite securing the parent top-level domain (TLD) – demonstrates a critical misunderstanding: DNSSEC requires a chain of trust from root to final record. By neglecting the “children” zones, Capita left 1.7 million civil servants exposed to redirection to fraudulent login pages, credential theft, and mass cyber fraud – a gross negligence with notice.
Learning Objectives:
- Understand the difference between DNSSEC-secured parent zones and insecure child zones, and why the latter breaks the chain of trust.
- Learn how to audit DNS zones for insecure RRsets (Resource Record sets) using command-line tools on Linux and Windows.
- Implement a step-by-step DNSSEC signing process for a child zone, including key generation, zone signing, and parent‑child delegation.
You Should Know:
- Parent vs. Child Zones: Why “Secure Parent” Means Nothing Without Child Signing
A DNSSEC-secured parent zone publishes DS (Delegation Signer) records that point to the child’s DNSKEY. However, if the child zone itself does not sign its own RRsets (A, AAAA, MX, etc.), any resolver validating the chain will treat the child data as insecure – or worse, an attacker can spoof responses without triggering validation errors.
Step‑by‑step guide to verify DNSSEC chain:
- On Linux – Use `dig` to check parent DS records and child signatures.
Query parent zone for DS records (example: csps.gov.uk) dig +dnssec csps.gov.uk DS @a.iana-servers.net Query child zone for signed RRsets dig +dnssec csps.gov.uk A @ns1.csps.gov.uk Use delv (DNSEC-aware resolver) to validate chain delv @8.8.8.8 csps.gov.uk A +rtrace
- On Windows – Use `nslookup` with DNSSEC options (PowerShell).
nslookup -type=DS csps.gov.uk 8.8.8.8 nslookup -type=DNSKEY csps.gov.uk ns1.csps.gov.uk
- Interpretation: If the child zone returns `SERVFAIL` or missing `ad` (authenticated data) flag, signatures are absent or broken. Capita’s assessment showed 49 insecure RRsets vs. only 4 secure ones – a near-total failure.
2. Auditing Insecure RRsets: Identifying Exposure to Spoofing
Without child‑zone signatures, an attacker on the network can forge DNS responses, redirecting pension portal logins to a phishing site. Auditing requires enumerating all RRsets in a zone and verifying their `RRSIG` records.
Step‑by‑step audit using `dig` and `dnssec-verify` (Linux):
Perform zone transfer (if allowed) or iterative query
dig axfr csps.gov.uk @ns1.csps.gov.uk > zone.export
Verify each RRset's signatures
dnssec-verify -z zone.export
Count signed vs. unsigned records
grep -c "^. RRSIG" zone.export
grep -c "^. IN A" zone.export | xargs -I {} echo "Total A records: {}"
For Windows, use `Resolve-DnsName` with `-DnssecOK`:
Resolve-DnsName csps.gov.uk -Type A -DnssecOK -Server 8.8.8.8 | Select-Object Name, Type, IPAddress, DNSSECStatus
What to look for: A `DNSSECStatus` of `Insecure` or `Unverified` means the child zone is not signed – exactly the condition Capita allowed to persist for five months after executive warning.
3. Hardening Child Zones: Full DNSSEC Signing Walkthrough
To close the vulnerability, zone administrators must generate ZSKs (Zone Signing Keys) and KSKs (Key Signing Keys), sign the zone, and publish DS records upstream. Below is a production‑ready workflow using `dnssec‑keygen` and `dnssec‑signzone` (Bind9 tools).
Step‑by‑step DNSSEC signing:
Generate KSK (2048-bit RSA) and ZSK (1024-bit) cd /var/named/keys dnssec-keygen -a RSASHA256 -b 2048 -n ZONE csps.gov.uk dnssec-keygen -a RSASHA256 -b 1024 -n ZONE -f KSK csps.gov.uk Sign the zone file dnssec-signzone -A -3 $(date +%Y%m%d%H%M%S) -o csps.gov.uk -k Ksk.key db.csps.gov.uk Zsk.key Output: db.csps.gov.uk.signed – contains RRSIG and NSEC/NSEC3 records
Deploy to primary DNS server and configure named.conf to serve the signed zone:
zone "csps.gov.uk" {
type master;
file "/var/named/db.csps.gov.uk.signed";
key-directory "/var/named/keys";
auto-dnssec maintain;
inline-signing yes;
};
Finally, submit the DS record hash to the parent registrar (e.g., gov.uk TLD). Without this step, the parent remains secure while the child stays exposed – exactly Capita’s fatal oversight.
4. Mitigating DNS Spoofing Without DNSSEC (Emergency Workarounds)
For organizations unable to immediately sign zones, apply network‑level controls to reduce spoofing risk. These are not replacements but stop‑gaps.
Linux (Unbound resolver with validation):
Install unbound, enable DNSSEC validation on the resolver itself sudo apt install unbound -y echo "server: val-override-date: yes val-log-level: 2 val-permissive-mode: no" >> /etc/unbound/unbound.conf sudo systemctl restart unbound
Windows (DNS over HTTPS/TLS):
Force DNS over HTTPS for all queries via PowerShell
Set-DnsClientServerAddress -InterfaceAlias "Ethernet" -ServerAddresses ("1.1.1.1", "9.9.9.9")
Set-DnsClientDohServerAddress -ServerAddress "1.1.1.1" -DohTemplate "https://cloudflare-dns.com/dns-query"
Cloud hardening (AWS Route53 with DNSSEC) – Enable DNSSEC signing for hosted zones and establish chain of trust via Key Signing Key (KSK) in AWS Certificate Manager.
5. Continuous Monitoring with Threat Intelligence Feeds
Capita ignored threat intelligence reports shared on 6 December 2025. Automate detection of insecure child zones across your assets.
Script to monitor DNSSEC status daily:
!/bin/bash
DOMAINS=("csps.gov.uk" "capita-pensions.co.uk")
for domain in "${DOMAINS[@]}"; do
if dig +dnssec $domain A +short | head -1 | grep -q ".$"; then
echo "ALERT: $domain failed DNSSEC validation" | mail -s "DNSSEC Failure" [email protected]
fi
done
Integrate with SIEM (Splunk/ELK) – Parse `named.log` for “no valid RRSIG” or “insecure response” entries. Set up real‑time alerts when a child zone’s `ad` flag is absent for more than 24 hours.
What Undercode Say:
- Key Takeaway 1: Securing the parent TLD without signing child zones creates a dangerous illusion of safety – attackers target the weak link. Capita’s 49 insecure RRsets vs. 4 secure ones is not a technical oversight; it’s willful negligence after explicit warnings.
- Key Takeaway 2: DNSSEC must be applied recursively from root to leaf. Any break – including missing DS records at the parent or unsigned RRsets in the child – nullifies the entire chain, enabling mass credential theft, session hijacking, and fraud for over 1.7 million victims.
Prediction:
Within 18 months, regulators (ICO, GDPR authorities) will mandate full‑chain DNSSEC validation for any public sector IT provider, with fines escalating per insecure child zone. Moreover, cyber insurance underwriters will refuse coverage to firms that cannot prove automated daily DNSSEC auditing – turning Capita’s current £15 million fine into a fraction of future industry-wide penalties. Expect class‑action lawsuits from affected pensioners, forcing DNS security to become a board‑level compliance requirement alongside TLS and endpoint protection.
▶️ Related Video (82% Match):
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: Andy Jenkinson – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
