Malware

EMudhra Intermediate CA Certificates Compromised

3 min read

Executive Summary

Eight intermediate certificate authority (CA) private keys belonging to Indian CA eMudhra Limited were compromised due to a critical cryptographic defect during the certificate generation process. The private keys in this incident were generated with insufficient randomness, allowing potential attackers to derive the private keys from the public certificates.

The weakness in cryptography allows third parties to:

Derive the private keys
Sign unauthorized public TLS certificates
Execute meddler-in-the-middle (MitM) traffic interception, impersonation or session hijacking against targeted domains

Major browser and operating system (OS) vendors have moved to revoke or untrust these intermediate CAs.

eMudhra has revoked the eight certificates.

Palo Alto Networks is designed to assist customers with managing certificate lifecycles through its Palo Alto Networks Next-Gen Trust Security solution. This solution is designed to provide customers with the capabilities needed to react to situations like the eMudhra incident.

Palo Alto Networks also recommends the following activities, which we describe in more detail in the Interim Guidance section:

Audit public and internal public key infrastructure (PKI) assets
Inspect code repositories and build pipelines
Audit internal systems and custom trust stores
Immediate certificate reissuance
Force emergency trust store updates
Enforce strict revocation checking
Query network egress and proxy logs
Audit network telemetry for MitM activity
Review authentication and identity logs
Implement Certificate Transparency (CT) monitoring
Enforce Certificate Authority Authorization (CAA) records
Harden automated certificate lifecycle management (ACME/CLM)

Organizations can access tailored adversary intelligence, direct analyst consultations, and specialized exposure tracking through Unit 42 Threat Intel Services and its Deep and Dark Web Service.

The Unit 42 Incident Response team can also be engaged to help with a compromise or to provide a proactive assessment to lower your risk.

Interim Guidance

Palo Alto Networks recommends the following actions to address this issue:

Discovery and internal exposure assessment
- Audit public and internal PKI assets: Inventory all public-facing services, web applications, API endpoints, VPN gateways and internal infrastructure. Identify any active TLS/SSL certificates chaining up to eMudhra intermediate CAs.
- Inspect code repositories and build pipelines: Audit software projects, containers and deployment scripts to ensure intermediate eMudhra certificates or hard-coded trust anchors were not bundled into applications, API clients or custom runtime environments.
- Audit internal systems and custom trust stores: Search for eMudhra roots or intermediates stored within custom enterprise trust stores (e.g., Linux /etc/ssl/certs, Java keystores, Python certifi bundles, Docker base images and mobile application bundles).

Technical containment and certificate revocation
- Immediate certificate reissuance: If any system uses a certificate issued under the compromised eMudhra intermediate CAs, immediately revoke and re-issue the certificate through an alternative, fully trusted CA.
- Force emergency trust store updates: Deploy updated root and intermediate certificate trust stores via mobile device management (MDM) across all endpoints, servers and container images to explicitly distrust or revoke the affected eMudhra intermediates.
- Enforce strict revocation checking: Configure enterprise web proxies, API gateways, outbound egress controls and security appliances to strictly enforce certificate revocation list (CRL) and Online Certificate Status Protocol (OCSP) checking, blocking any connection presenting revoked chains.

Active threat hunting and log analysis
- Query network egress and proxy logs: Search network, proxy and DNS logs for anomalous traffic attempting connections to unknown external IPs using eMudhra-signed certificates.
- Audit network telemetry for MitM activity: Look for unexplained spikes in SSL/TLS handshake failures, certificate validation errors or untrusted issuer warnings. These spikes could indicate active MitM tampering or proxy insertion attempts.
- Review authentication and identity logs: Inspect authentication logs for sensitive services (SSO, VPN, cloud portals) accessed around the time frame of the compromise to ensure valid user sessions were not intercepted or replayed via rogue certificates.

Long-term governance and supply chain hardening
- Implement CT monitoring: Monitor public CT logs (using tools like crt.sh or automated CT log monitors) for any unauthorized certificates issued for your company's registered domains.
- Enforce CAA records: Implement or update DNS CAA records for all organizational domains to explicitly restrict which CAs are authorized to issue certificates on your behalf.
- Harden ACME/CLM: Transition to automated CLM platforms using short-lived certificates to minimize the impact window of potential future CA key compromises.

Palo Alto Networks Product Protections for eMudhra TLS Certificate Compromise

Palo Alto Networks customers can leverage a variety of product protections and updates to identify and defend against this threat.

Organizations can access tailored adversary intelligence, direct analyst consultations, and specialized exposure tracking through Unit 42 Threat Intel Services and its Deep and Dark Web Service.

If you think you might have been compromised or have an urgent matter, get in touch with the Unit 42 Incident Response team or call:

North America: Toll Free: +1 (866) 486-4842 (866.4.UNIT42)
UK: +44.20.3743.3660
Europe and Middle East: +31.20.299.3130
Asia: +65.6983.8730
Japan: +81.50.1790.0200
Australia: +61.2.4062.7950
India: 000 800 050 45107
South Korea: +82.080.467.8774

Next-Gen Trust Security

Palo Alto Networks Next-Gen Trust Security (NGTS) is designed to unify certificate lifecycle management and modern PKI within the network control plane to eliminate the risks of manual, siloed operations. By integrating discovery and automation into Strata Cloud Manager, NGTS provides the cryptographic agility needed to manage compressing 47-day lifecycles and respond to emergency events with automated reissuance and synchronized enforcement to ensure business continuity. The Next-Gen Trust Security solution is designed to provide customers with the capabilities needed to react to situations like the eMudhra incident.