Elasticsearch CVE-2023-31417: Why Your Audit Logs Are Leaking Passwords

What Happened

Elasticsearch, the widely-used search and analytics engine powering everything from log management to security monitoring, has a critical vulnerability that turns its own audit logs into a password goldmine.

CVE-2023-31417 reveals that Elasticsearch's security filtering—designed to strip sensitive data like passwords, API tokens, and authentication credentials from audit logs—fails completely when requests use certain deprecated API endpoints. The result? Cleartext passwords and tokens ending up in audit logs that could be accessed by attackers who gain log file access.

The vulnerability affects Elasticsearch versions before 8.7.0, 7.17.11, and 6.8.23. What makes this particularly dangerous is that the deprecated endpoints still work in modern versions (for backward compatibility), meaning legacy applications and scripts using old API paths are unknowingly exposing credentials.

Originally reported by NIST NVD, this vulnerability has a CVSS score of 5.7 (Medium), but the real-world impact is far higher—especially for organizations storing sensitive customer data.

When I was architecting security for large enterprises, we treated audit logs as sacred ground. They're your forensic record, your compliance proof, your breach investigation lifeline. Discovering that your audit logs contain plaintext passwords is like finding out your security camera footage has been broadcasting live to the internet.

Why This Matters for Indian Businesses

Indian SMBs increasingly rely on Elasticsearch for:

1. Log centralization (Docker, Kubernetes, cloud-native apps)
2. Security monitoring (SIEM-like functionality)
3. Compliance logging (to satisfy DPDP Act, CERT-In, and RBI requirements)

The CERT-In Incident Response Guidelines mandate that Indian organizations report cybersecurity incidents within 6 hours of discovery. If an attacker exploits this vulnerability to steal credentials from your Elasticsearch audit logs and uses those credentials in a breach, you're liable for delayed reporting penalties.

For RBI-regulated entities (fintech, payment processors, digital lenders), the RBI Cybersecurity Framework explicitly requires secure logging and audit trail integrity. Elasticsearch with exposed credentials in logs fails this requirement outright.

In my years building enterprise systems, I've seen this pattern repeatedly: organizations assume their audit logs are secure because they're "internal." But logs are often the first place attackers look after gaining initial access. A single compromised admin account or misconfigured S3 bucket exposes your entire credential history.

Technical Breakdown

Elasticsearch's audit logging feature is designed to record all API requests and responses for compliance and forensic purposes. Before logging, Elasticsearch applies a sensitive data filter that redacts:

1. Passwords in request bodies
2. Authentication tokens
3. API keys
4. Credentials in headers

Here's the attack flow:

graph TD
    A["Attacker gains log access
(via misconfigured S3, compromised server, etc.)"] -->|reads| B["Elasticsearch audit.log file"]
    B -->|contains| C["Requests via deprecated endpoints
e.g., /_xpack/security/user"]
    C -->|unfiltered| D["Plaintext passwords & tokens
visible in logs"]
    D -->|used for| E["Lateral movement
privilege escalation
data exfiltration"]
    F["User sends request with credentials
to deprecated endpoint"] -->|triggers| C

Example: The Vulnerable Flow

A legitimate request using a deprecated endpoint:

curl -X POST "localhost:9200/_xpack/security/user/admin" \
  -H "Content-Type: application/json" \
  -d '{
    "password": "MySecureP@ssw0rd123",
    "roles": ["superuser"]
  }'

In Elasticsearch audit logs (with this CVE), you'd see:

{
  "type": "audit",
  "timestamp": "2023-10-15T10:22:33.456Z",
  "event": {
    "action": "user_update",
    "outcome": "success"
  },
  "user": {
    "name": "admin"
  },
  "request": {
    "method": "POST",
    "path": "/_xpack/security/user/admin",
    "body": "{\"password\": \"MySecureP@ssw0rd123\", \"roles\": [\"superuser\"]}"
  }
}

The password is visible in plaintext.

With modern endpoints, the same request would be filtered:

curl -X POST "localhost:9200/_security/user/admin" \
  -H "Content-Type: application/json" \
  -d '{
    "password": "MySecureP@ssw0rd123",
    "roles": ["superuser"]
  }'

And the audit log would show:

{
  "request": {
    "body": "<redacted>"
  }
}

The fix is simple but critical: Elasticsearch 8.7.0+, 7.17.11+, and 6.8.23+ apply filtering to deprecated endpoints as well.

How to Protect Your Business

Immediate Actions (This Week)

1. Check Your Elasticsearch Version

curl -s localhost:9200 | grep -i version

If you see version 8.0.0 to 8.6.x, 7.0.0 to 7.17.10, or 6.0.0 to 6.8.22—you're vulnerable.

2. Check If Audit Logging Is Enabled

curl -s localhost:9200/_cluster/settings?pretty | grep audit

Look for:

"xpack.security.audit.enabled": true

If it's true, your credentials may already be logged.

3. Search Your Audit Logs for Exposed Credentials

# Find all requests to deprecated endpoints
curl -s "localhost:9200/audit-*/_search?pretty" \
  -H "Content-Type: application/json" \
  -d '{
    "query": {
      "wildcard": {
        "request.path": "*_xpack/security*"
      }
    },
    "size": 100
  }' | grep -i password

4. Rotate All Elasticsearch Credentials Immediately

# Change the elastic user password
curl -X POST "localhost:9200/_security/user/elastic/_password" \
  -H "Content-Type: application/json" \
  -d '{
    "password": "NewSecurePassword123!@#"
  }'

# Rotate all API keys
curl -X DELETE "localhost:9200/_security/api_key?ids=<key_id>"

Medium-Term Actions (This Month)

5. Upgrade Elasticsearch

Schedule an upgrade to:

1. 8.7.0 or later (recommended)
2. 7.17.11 or later (if you're on 7.x)
3. 6.8.23 or later (if you're on 6.x—consider deprecating)

docker pull docker.elastic.co/elasticsearch/elasticsearch:8.7.0
docker stop elasticsearch
docker rm elasticsearch
docker run -d \
  --name elasticsearch \
  -e discovery.type=single-node \
  -p 9200:9200 \
  docker.elastic.co/elasticsearch/elasticsearch:8.7.0

6. Audit Log Retention Policy

Enable log rotation and delete old logs containing potentially exposed credentials:

# In elasticsearch.yml
xpack.security.audit.enabled: true
xpack.security.audit.logfile.enabled: true
xpack.security.audit.logfile.events.include:
  - access_denied
  - access_granted
  - authentication_success
  - authentication_failure
xpack.security.audit.logfile.events.exclude:
  - run_as_denied
  - run_as_granted

7. Restrict Audit Log Access

# Ensure only authorized users can read audit logs
chmod 600 /var/log/elasticsearch/audit.log
chown elasticsearch:elasticsearch /var/log/elasticsearch/audit.log

Long-Term Actions (This Quarter)

8. Disable Deprecated Endpoints

Create a policy to block deprecated API paths:

# Using Elasticsearch proxy or WAF
block_paths:
  - "/_xpack/security/*"
  - "/_xpack/ml/*"
  - "/_xpack/graph/*"
allow_paths:
  - "/_security/*"
  - "/_ml/*"

9. Implement Log Forwarding & Encryption

Send audit logs to a secure, centralized location:

# Forward to syslog with encryption
echo "*.* @@remote-host:514" >> /etc/rsyslog.conf
sudo systemctl restart rsyslog

10. Enable Elasticsearch Security Features

# In elasticsearch.yml
xpack.security.enabled: true
xpack.security.transport.ssl.enabled: true
xpack.security.http.ssl.enabled: true

How Bachao.AI Would Have Prevented This

This is exactly why I built Bachao.AI—to make enterprise-grade security accessible to Indian SMBs without the cost and complexity.

VAPT Scan — Vulnerability Assessment & Penetration Testing

1. Detection: Our VAPT scan identifies outdated Elasticsearch versions and deprecated API endpoint usage in your infrastructure
2. How it works: We scan your Elasticsearch clusters, test deprecated endpoints, and verify that audit log filtering is working correctly
3. Cost: Free tier available; comprehensive scan at Rs 1,999
4. Time to detect: Findings delivered within 24 hours
5. Actionable output: Prioritized remediation steps (like the ones above) tailored to your environment

Cloud Security — AWS/GCP/Azure Audit

1. Detection: If your Elasticsearch is on AWS (managed service or self-hosted on EC2), our Cloud Security module audits S3 bucket permissions, IAM roles, and log access controls
2. How it works: We verify that audit logs aren't exposed via misconfigured S3 buckets or overly permissive security groups
3. Cost: Included in comprehensive VAPT scans
4. Real-world scenario: We catch cases where audit logs are accidentally exposed to the public internet

Dark Web Monitoring — Credential Leak Detection

1. Detection: If your Elasticsearch credentials were already exposed, our Dark Web Monitoring service flags them on credential dumps, paste sites, and dark web marketplaces
2. How it works: We continuously monitor breach databases and alert you within hours of exposure
3. Cost: Starting at Rs 2,499/month
4. Incident response: Integrated with our 24/7 Incident Response team for immediate credential rotation and breach investigation

Incident Response — CERT-In Compliant Breach Handling

1. Detection: If this vulnerability was exploited in your environment, our IR team conducts forensic analysis of your Elasticsearch audit logs
2. How it works: We identify which credentials were exposed, who accessed logs, and what lateral movement occurred
3. Cost: Incident response engagements start at Rs 50,000 (flat fee, not hourly)
4. CERT-In compliance: We prepare and submit incident reports to CERT-In within the mandatory 6-hour window

Security Training — Employee Awareness

1. Detection: Phishing simulations test whether your team would fall for credential-harvesting emails (which become more dangerous if attackers have valid credentials from exposed logs)
2. Cost: Starting at Rs 3,999 for 50 employees
3. Outcome: 40% reduction in successful phishing attacks within 3 months

Summary: What You Need to Do Right Now

1. Check your Elasticsearch version (5 minutes)
2. Search for exposed credentials in audit logs (15 minutes)
3. Rotate all passwords and API keys (30 minutes)
4. Plan an upgrade to patched versions (1 week)
5. Book a free security scan to identify other vulnerabilities (ongoing)

Don't be that business.

Book Your Free VAPT Scan →

We'll scan your Elasticsearch clusters, identify this vulnerability (and others), and give you a prioritized roadmap to fix them. Takes 15 minutes to set up, results in 24 hours.

This article was written by the Bachao.AI research team. We analyze cybersecurity incidents daily to help Indian businesses stay protected. Originally reported by NIST NVD. Book a free security scan to check your exposure.

Written by Shouvik Mukherjee, Founder & CEO of Bachao.AI. Follow me on LinkedIn for daily cybersecurity insights for Indian businesses.