How to remediate – Unpassworded ‘r00t’ account

1. Introduction

The vulnerability is an unpassworded ‘r00t’ account on a remote host. This means anyone can log in as the most powerful user without needing a password. This matters to businesses because it allows attackers to take complete control of affected systems, potentially stealing data or disrupting services. Systems commonly affected are Linux and Unix servers. A successful exploit could compromise confidentiality, integrity, and availability.

2. Technical Explanation

The ‘r00t’ account has no password set, allowing direct access without authentication. An attacker can connect to the system remotely and execute commands with full privileges. The precondition is network connectivity to the affected host. This vulnerability is tracked as CVE-1999-0502.

• Root cause: The ‘r00t’ account lacks a password, violating security best practices.
• Exploit mechanism: An attacker connects via SSH or another remote access method and attempts to log in as ‘r00t’. If no password is required, they gain immediate access. For example, using `ssh r00t@`.
• Scope: Primarily affects Linux and Unix systems where the ‘r00t’ account exists with a missing password.

3. Detection and Assessment

You can check for this vulnerability by attempting to log in as ‘r00t’ without a password, or by reviewing system configuration files.

• Quick checks: Attempt to SSH into the target machine as root with no password provided.
• Scanning: Nessus plugin ID 10853 can identify unpassworded accounts. This is an example only.
• Logs and evidence: Check `/var/log/auth.log` or similar authentication logs for successful logins as ‘r00t’ without a password.

ssh r00t@

4. Solution / Remediation Steps

To fix this issue, set a strong password for the ‘r00t’ account or disable it entirely.

4.1 Preparation

• Ensure you have an alternative administrative account with sudo privileges. Roll back by restoring the snapshot if needed.
• Changes should be scheduled during a maintenance window and approved by the IT security team.

4.2 Implementation

1. Step 1: Set a strong password for the ‘r00t’ account using the `passwd` command.
2. Step 2: Verify the password change was successful by attempting to log in as ‘r00t’ with the new password.

4.3 Config or Code Example

Before

# /etc/shadow (root entry has no password hash)
root:!*::0:99999:99999:::/root:/bin/bash

After

# /etc/shadow (root entry now has a password hash)
root:$6$rounds=5000$salt$hashed_password::0:99999:99999:::/root:/bin/bash

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this issue.

• Practice 1: Least privilege – avoid using the ‘r00t’ account for day-to-day tasks, reducing impact if compromised.
• Practice 2: Strong password policies – enforce complex passwords and regular changes to all accounts.

4.5 Automation (Optional)

The following script can be used to set a default password on root account. Use with caution.

#!/bin/bash
# Set a strong password for the root account
NEW_PASSWORD="YourStrongPassword"
echo "root:$6$rounds=5000$salt$hashed_password" | chpasswd

5. Verification / Validation

Confirm the fix by attempting to log in as ‘r00t’ with a password, and verifying that login without a password fails.

• Post-fix check: Attempt to SSH into the target machine as root with no password provided; it should be rejected.
• Re-test: Run the `ssh r00t@` command from section 3, which should now fail.
• Smoke test: Verify that you can log in as a standard user and perform basic system administration tasks using sudo.
• Monitoring: Monitor `/var/log/auth.log` for failed login attempts as ‘r00t’ without a password.

ssh r00t@ (should fail)

6. Preventive Measures and Monitoring

Update security baselines to include strong password requirements, and implement regular system audits.

• Baselines: Update your Linux hardening baseline or CIS benchmark to enforce passwords on all accounts, including ‘r00t’.
• Pipelines: Integrate static code analysis (SCA) into your CI/CD pipeline to detect insecure configurations.
• Asset and patch process: Review system configurations regularly as part of a vulnerability management program.

7. Risks, Side Effects, and Roll Back

Setting a password may break existing scripts or automated processes that rely on unpassworded ‘r00t’ access.

• Risk or side effect 2: Lockout if the new password is forgotten – document the password securely and have a recovery process in place.
• Roll back: Restore the system snapshot taken in section 4.1.

8. References and Resources

Links to resources about this vulnerability.

• Vendor advisory or bulletin: No specific vendor advisory available for CVE-1999-0502.
• NVD or CVE entry: CVE-1999-0502
• Product or platform documentation relevant to the fix: Consult your Linux distribution’s documentation on user account management and password security.