How to remediate – Unpassworded ‘jill’ Account

1. Introduction

The vulnerability is an unpassworded ‘jill’ account on a remote host. This means anyone gaining access to the system can use this account without needing a password, potentially allowing them to take control of the system. Systems running user accounts are usually affected. A successful exploit could compromise confidentiality, integrity and availability of data on the affected system.

2. Technical Explanation

The ‘jill’ account has no password set, meaning authentication is bypassed for that specific user. An attacker can log in directly as ‘jill’ without providing credentials if they have network access to the host. This vulnerability is tracked as CVE-1999-0502. A simple example would be an attacker gaining shell access via SSH and logging in as ‘jill’ with a blank password.

• Root cause: The account ‘jill’ was created without a password being assigned, or the password has been removed.
• Exploit mechanism: An attacker attempts to log in to the system using the username ‘jill’ and leaves the password field blank. If successful, they gain access with the privileges associated with that account.
• Scope: Affected platforms are any operating systems supporting user accounts, including Linux, Windows, macOS and others.

3. Detection and Assessment

You can confirm if a system is vulnerable by checking for an account named ‘jill’ without a password set. A quick check involves listing all users on the system. More thorough assessment requires examining user account details.

• Quick checks: On Linux, use the command getent passwd jill. If the output shows ‘jill’ with an empty password field (represented by ‘x’), the account is vulnerable.
• Scanning: Nessus vulnerability ID 10286 may detect this issue as an example only.
• Logs and evidence: Check system authentication logs for successful logins from user ‘jill’ without a password provided. Log locations vary by operating system, but typically include /var/log/auth.log or Windows Event Logs under Security.

getent passwd jill

4. Solution / Remediation Steps

Fix the issue by setting a password for the ‘jill’ account, or disabling it if no longer needed. These steps are small and can be easily reversed.

4.1 Preparation

• No services need to be stopped for this remediation.

4.2 Implementation

1. Step 1: Set a strong password for the ‘jill’ account using the appropriate command for your operating system. On Linux, use passwd jill and follow the prompts to enter a new password.
2. Step 2: Verify that the password has been set correctly by attempting to log in as ‘jill’ with the new password.

4.3 Config or Code Example

Before

jill:x:1001:1001::/home/jill:/bin/bash

After

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

4.4 Security Practices Relevant to This Vulnerability

Practices that directly address this vulnerability type include least privilege and secure defaults. Least privilege limits the impact if an account is compromised. Secure defaults ensure accounts are created with strong passwords or disabled by default.

• Practice 1: Implement a policy of least privilege, ensuring users only have access to resources they need.
• Practice 2: Enforce secure defaults for new user accounts, requiring password complexity and preventing blank passwords.

4.5 Automation (Optional)

#!/bin/bash
# Script to set passwords for unpassworded accounts
for user in $(getent passwd | awk -F: '$7 == "" {print $1}'); do
  echo "Setting password for user: $user"
  passwd "$user" <<< 'new_secure_password' # Replace with a secure password generation method.
done

5. Verification / Validation

Confirm the fix by attempting to log in as 'jill' with the new password and verifying successful authentication. Re-run the earlier detection check to confirm no unpassworded accounts remain. Perform a basic service smoke test.

• Post-fix check: Run getent passwd jill again. The output should show a hashed password field instead of 'x'.
• Re-test: Re-run the command from step 3, and confirm no accounts are listed with an empty password field.
• Smoke test: Log in to the system as another user and verify key services (e.g., file sharing, printing) still function correctly.
• Monitoring: Monitor authentication logs for failed login attempts for 'jill', which could indicate a brute-force attack or misconfiguration.

getent passwd jill

6. Preventive Measures and Monitoring

Update security baselines to include password policies and account lockout settings. Implement checks in CI/CD pipelines to prevent the creation of accounts without passwords. Establish a regular patch or configuration review cycle.

• Baselines: Update your system baseline to require strong passwords for all user accounts, as defined by CIS control 1.3.
• Asset and patch process: Implement a monthly review of user account configurations to identify and remediate any unpassworded accounts.

7. Risks, Side Effects, and Roll Back

Setting an incorrect password could lock the 'jill' account. Disabling the account may impact applications or services that rely on it. To roll back, re-enable the account if disabled, or restore from a system snapshot.

• Risk or side effect 1: Setting an invalid password can cause account lockout. Mitigation is to use a known valid password during testing.
• Roll back: If the account cannot be used after setting a password, revert to disabling it using usermod -L jill (Linux) or through Active Directory Users and Computers (Windows). Alternatively, restore from the system snapshot taken prior to making changes.

8. References and Resources

• 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: Refer to your operating system's documentation on user account management and password policies.