How to remediate – Unprotected ‘admin’ Account

1. Introduction

The ‘admin’ account vulnerability refers to an administrative account on a remote host that has no password set. This is a serious security issue because it allows anyone to gain full control of the system without authentication. Systems commonly affected are servers, network devices and virtual machines running various operating systems. A successful exploit could lead to complete loss of confidentiality, integrity, and availability of data and services.

2. Technical Explanation

The root cause is typically a default configuration or an administrator failing to set a password during system setup. An attacker can directly log in as the ‘admin’ user without needing credentials. CVE-1999-0502 describes this vulnerability. For example, an attacker could attempt to connect via SSH or RDP and simply enter ‘admin’ as the username with no password. Affected systems include those running older versions of Windows NT and similar operating systems where default accounts were often shipped without enforced password protection.

• Root cause: Missing password on the ‘admin’ account due to a default configuration or administrative oversight.
• Exploit mechanism: An attacker attempts login using the username ‘admin’ with an empty password.
• Scope: Older versions of Windows NT and similar operating systems are known to be affected.

3. Detection and Assessment

You can confirm this vulnerability by attempting a login as ‘admin’ without providing a password. A thorough method involves auditing all accounts on the system for those with blank passwords.

• Quick checks: Attempt to log in using the username ‘admin’ with no password via SSH or RDP.
• Scanning: Nessus plugin ID 10429 may identify this issue, but results should be verified manually.
• Logs and evidence: Check system event logs for successful logins from the ‘admin’ account without a source IP address or unusual login times.

net user admin | find "Password:"

4. Solution / Remediation Steps

To fix this issue, set a strong password for the ‘admin’ account or disable it entirely. Only apply these steps to systems where the ‘admin’ account is legitimately required.

4.1 Preparation

• Ensure you have an alternative administrative account available. A roll back plan involves restoring from backup or re-enabling the account with a temporary password.
• Change windows should be scheduled during off peak hours and approved by the IT security team.

4.2 Implementation

1. Step 1: Set a strong, unique password for the ‘admin’ account using the command line or GUI tools.
2. Step 2: Verify that the password change was successful by attempting to log in with the new credentials.
3. Step 3: If the ‘admin’ account is not required, disable it to eliminate the risk of unauthorized access.

4.3 Config or Code Example

Before

net user admin /domain

After

net user admin * /domain

4.4 Security Practices Relevant to This Vulnerability

Practices that directly address this vulnerability include least privilege and secure defaults. Least privilege limits the impact if an account is compromised, while secure defaults prevent weak configurations from being shipped with systems.

• Practice 1: Implement least privilege by granting only necessary permissions to administrative accounts.
• Practice 2: Enforce strong password policies and require administrators to change default passwords immediately upon system setup.

4.5 Automation (Optional)

A PowerShell script can be used to check for blank passwords on all local accounts. Use caution when running scripts that modify account settings.

Get-LocalUser | Where-Object {$_.PasswordNull -eq $true} | ForEach-Object {Write-Host "Account $($_.Name) has a null password."}

5. Verification / Validation

• Post-fix check: Attempt to log in as ‘admin’ without a password; it should fail.
• Re-test: Run the command from section 3 and confirm no accounts report a null password.
• Smoke test: Verify that other administrative accounts can still log in successfully.
• Monitoring: Monitor system event logs for failed login attempts using the ‘admin’ account, which could indicate ongoing attacks.

net user admin | find "Password:"

6. Preventive Measures and Monitoring

Update security baselines to include a requirement for strong passwords on all administrative accounts. Implement checks in CI/CD pipelines to prevent systems from being deployed with default or blank passwords.

• Baselines: Update your system hardening baseline to require setting a password for the ‘admin’ account during initial setup.
• Pipelines: Add automated security scans to deployment pipelines that flag accounts with weak or missing passwords.

7. Risks, Side Effects, and Roll Back

Setting a strong password may cause compatibility issues with older applications that rely on the ‘admin’ account without authentication. Disabling the ‘admin’ account could disrupt services if it is required for legitimate operations. To roll back, restore from backup or re-enable the account.

• Risk or side effect 2: Service disruption if ‘admin’ is required for legitimate operations. Mitigation: Ensure an alternative administrative account exists.
• Roll back: Restore the system from backup, or re-enable the ‘admin’ account with a temporary password.

8. References and Resources

• Vendor advisory or bulletin: CERT Advisory CA-1999-05
• NVD or CVE entry: CVE-1999-0502
• Product or platform documentation relevant to the fix: Microsoft documentation on account management.