How to remediate – Unpassworded ‘tutor’ Account

1. Introduction

The ‘tutor’ account vulnerability involves an account on a remote host that has no password set. This means anyone with access to the system could potentially log in as this user without authentication. It primarily affects systems running services where local accounts are used for administration or specific application functions, and can impact confidentiality, integrity, and availability if exploited. A successful attack could allow an attacker to gain further privileges on the affected system.

2. Technical Explanation

The root cause of this vulnerability is a missing password configuration for the ‘tutor’ account. An attacker can exploit this by attempting to log in as the ‘tutor’ user without providing any credentials. This is often possible due to default configurations or administrative oversight. The CVE associated with this issue is CVE-1999-0502.

• Root cause: A password has not been set for the local account ‘tutor’.
• Exploit mechanism: An attacker attempts a login as user ‘tutor’ without supplying a password. If successful, they gain access with the privileges assigned to that account. For example, an attacker could use SSH or RDP if enabled and configured to allow local logins.
• Scope: Affected platforms are those running operating systems allowing local accounts without mandatory password policies. This includes various Linux distributions and Windows versions.

3. Detection and Assessment

You can confirm the vulnerability by checking for the existence of an account with no password set. A quick check involves listing user accounts and their properties, while a thorough method requires examining account details specifically.

• Quick checks: On Linux systems, use the command getent passwd tutor. If the output shows a line without a password hash (represented by an ‘x’ or similar), the account has no password set.
• Scanning: Nessus vulnerability ID 10253 may detect this issue. This is provided as an example only, and results should be verified manually.
• Logs and evidence: Security logs may show failed login attempts with empty passwords for the ‘tutor’ account, but are unlikely to log successful logins without a password.

getent passwd tutor

4. Solution / Remediation Steps

To fix this issue, set a strong password for the ‘tutor’ account or disable it if it is not required.

4.1 Preparation

• No services need to be stopped directly, but consider potential impact on applications using this account. A roll back plan involves reverting any password changes or re-enabling the account if disabled.
• Changes should be scheduled during a maintenance window with appropriate approval from IT management.

4.2 Implementation

1. Step 1: Set a strong, unique password for the ‘tutor’ account using the system’s user management tools. On Linux, use the command passwd tutor and follow the prompts to enter a new password.
2. Step 2: Verify the password has been set correctly by attempting to log in as ‘tutor’ with the new password.
3. Step 3: If the account is not required, disable it using the system’s user management tools. On Linux, use the command usermod -L tutor.

4.3 Config or Code Example

Before

tutor:x:1001:1001::/home/tutor:/bin/bash

After

tutor:$6$rounds=5000$salt$hashedpassword:1001:1001::/home/tutor:/bin/bash

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this issue. Least privilege reduces the impact if an account is compromised, and regular password audits ensure accounts are properly secured.

• Practice 1: Implement least privilege principles by granting only necessary permissions to each account.
• Practice 2: Conduct regular password audits to identify and remediate weak or missing passwords.

4.5 Automation (Optional)

#!/bin/bash
# Script to set passwords for specific accounts
accounts=("tutor")
for account in "${accounts[@]}"; do
  if getent passwd "$account" | grep -q 'x:'; then
    echo "Setting password for $account..."
    passwd "$account" << EOF
newpassword
newpassword
EOF
  else
    echo "Account $account does not exist."
  fi
done

5. Verification / Validation

Confirm the fix by verifying that a strong password has been set for the 'tutor' account and that login attempts without a password fail.

• Post-fix check: Run getent passwd tutor again. The output should now show a password hash (e.g., $6$rounds=5000$salt$hashedpassword) instead of 'x'.
• Re-test: Attempt to log in as 'tutor' without providing a password. The login attempt should fail.
• Smoke test: Verify any applications or services using the 'tutor' account function correctly with the new password.
• Monitoring: Monitor security logs for failed login attempts with empty passwords for the 'tutor' account, which should no longer occur.

getent passwd tutor

6. Preventive Measures and Monitoring

Update your system’s security baseline to enforce strong password policies and regularly review user accounts. Consider adding checks in your CI/CD pipeline to prevent the creation of accounts without passwords.

• Baselines: Update a security baseline or policy (for example, CIS control 1.2) to require all local accounts to have strong passwords set.
• Pipelines: Add checks in CI or deployment pipelines to scan for accounts with missing passwords and fail builds if found.
• Asset and patch process: Implement a regular review cycle of user accounts and their permissions, at least quarterly.

7. Risks, Side Effects, and Roll Back

Changing the 'tutor' account password could disrupt applications or services relying on it. Disabling the account may impact functionality if it is actively used. If issues arise, revert the changes by resetting the password to blank or re-enabling the account.

• Roll back: If password changes cause issues, reset the password to blank using passwd -d tutor (Linux). If an account was disabled, re-enable it with usermod -U tutor (Linux).

8. References and Resources

• Vendor advisory or bulletin: No specific vendor advisory available for CVE-1999-0502.
• NVD or CVE entry: CVE