How to remediate – Unpassworded ‘jack’ Account

1. Introduction

The vulnerability is an unpassworded ‘jack’ account on a remote host. This means someone could access the system using this account without needing a password, potentially gaining control. Systems running any operating system with user accounts are affected. A successful attack could compromise confidentiality, integrity and availability of data on the system.

2. Technical Explanation

The ‘jack’ account has no password set, allowing anyone with network access to log in without authentication. An attacker can exploit this by directly attempting to connect to the host using the ‘jack’ username without providing a password. CVE-1999-0502 describes this general issue of accounts lacking passwords. For example, an attacker on the same network could use SSH or RDP to log in as ‘jack’.

• Root cause: The account was created or left configured without a password.
• Exploit mechanism: An attacker attempts login using the username ‘jack’ with no password provided.
• Scope: All systems where an account named ‘jack’ exists and has not been assigned a password.

3. Detection and Assessment

You can confirm if a system is vulnerable by checking for accounts without passwords. A quick check involves listing all users and looking for those with blank password fields. More thorough assessment requires examining account details specifically.

• Quick checks: Use the command `getent passwd jack` to see if the user exists, then examine `/etc/shadow` (Linux) or use PowerShell’s `Get-LocalUser | Where-Object {$_.PasswordLastSet -eq $null}` (Windows).
• Scanning: Nessus plugin ID 10386 may identify this issue. This is an example only.
• Logs and evidence: Audit logs might show failed login attempts with the ‘jack’ account, though absence of logs doesn’t guarantee security.

getent passwd jack

4. Solution / Remediation Steps

Fix this issue by setting a strong password for the ‘jack’ account or disabling it if not needed. Follow these steps carefully to avoid disrupting service.

4.1 Preparation

• Ensure you have an alternative administrator account available. Roll back by restoring the snapshot or reverting password change.
• Changes should be made during a maintenance window with appropriate approval from IT management.

4.2 Implementation

1. Step 1: Set a strong, unique password for the ‘jack’ account using `passwd jack` (Linux) or `Set-LocalUser -Name “jack” -Password (Convertto-SecureString “” -AsPlainText)` (Windows).
2. Step 2: Verify the password change by attempting to log in as ‘jack’ with the new password.
3. Step 3: If the account is not required, disable it using `usermod -L jack` (Linux) or `Disable-LocalUser -Name “jack”` (Windows).

4.3 Config or Code Example

Before

jack:x:1000:1000::/home/jack:/bin/bash

After

jack:$6$rounds=5000$salt$hashed_password:1000:1000::/home/jack:/bin/bash

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this issue. Least privilege reduces the impact of a compromised account. Regular password audits identify weak or missing passwords. Safe defaults should require strong passwords on new accounts.

• Practice 1: Implement least privilege, limiting access rights for all accounts to only what is necessary.
• Practice 2: Conduct regular password audits to identify and remediate accounts with weak or missing passwords.

4.5 Automation (Optional)

A script can automate password setting across multiple systems. Be cautious when automating password changes, especially in production environments.

#!/bin/bash
for host in $(cat /tmp/hostlist); do
  ssh $host "passwd jack"
done

5. Verification / Validation

Confirm the fix by attempting to log in with the new password and verifying that the old login method no longer works. A service smoke test confirms core functionality remains intact.

• Post-fix check: Attempt to SSH or RDP as ‘jack’ using the newly set password – successful login confirms the change.
• Re-test: Run `getent passwd jack` again and verify that a password hash is present in `/etc/shadow`.
• Smoke test: Test basic functionality of any services used by the ‘jack’ account to ensure they are still working correctly.
• Monitoring: Monitor audit logs for failed login attempts as ‘jack’ which could indicate ongoing attacks.

getent passwd jack

6. Preventive Measures and Monitoring

Update security baselines to enforce strong passwords on all accounts. Implement checks in CI/CD pipelines to prevent the creation of accounts without passwords. A regular patch cycle ensures systems are up-to-date with security fixes.

• Baselines: Update your system baseline or group policy to require a password for all user accounts.
• Pipelines: Add checks in CI/CD pipelines to scan for and reject account creation without passwords.
• Asset and patch process: Implement a regular review cycle of account configurations to identify and remediate any vulnerabilities.

7. Risks, Side Effects, and Roll Back

Changing the password could disrupt services if ‘jack’ is used by automated processes. Incorrectly setting the password can lock out users. Roll back by restoring the system snapshot or reverting the password change.

• Risk or side effect 1: Changing the password may break applications relying on unattended access with ‘jack’. Mitigate by testing changes in a non-production environment first.
• Roll back: Restore the system snapshot taken prior to making any changes, or revert the password change using the original configuration.

8. References and Resources

• Vendor advisory or bulletin: No specific vendor advisory available for this general issue.
• 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.