1. Introduction
2. Technical Explanation
The vulnerability occurs because the ‘help’ account is created with an empty password during system setup or remains unchanged from a default configuration. An attacker can directly log in to the system using this account if it’s accessible over the network. CVE-1999-0502 describes this issue. A simple example would be an attacker attempting to SSH into a server and successfully authenticating with username ‘help’ and no password.
- Root cause: The ‘help’ account is created without requiring a password, or the default password has not been changed.
- Exploit mechanism: An attacker attempts to log in using the ‘help’ account with an empty password. If successful, they gain access to the system. For example, using SSH:
ssh help@. - Scope: This affects systems where the ‘help’ account is enabled by default and not secured. Specific versions are not always documented but older systems are more likely to be affected.
3. Detection and Assessment
- Quick checks: Attempt to login via SSH or RDP using username ‘help’ and no password.
- Scanning: Nessus plugin ID 10384 may identify this vulnerability as an example.
- Logs and evidence: Check system authentication logs for successful logins from the ‘help’ account without a password. The exact log file location varies by operating system (e.g., /var/log/auth.log on Linux).
ssh help@4. Solution / Remediation Steps
Fix the issue by setting a strong password for the ‘help’ account or disabling it completely. These steps are small, testable and safe to roll back.
4.1 Preparation
- Ensure you have an alternative administrative account available in case of issues. A rollback plan is to restore from backup or re-enable the account with a default password and then disable it again.
- A change window may be needed depending on service criticality, requiring approval from the IT manager.
4.2 Implementation
- Step 1: Set a strong password for the ‘help’ account using the system’s user management tools. For example, in Linux:
passwd help. - Step 2: Alternatively, disable the ‘help’ account if it is not required:
userdel -r help(Linux).
4.3 Config or Code Example
Before
/etc/shadow:help::0:0:99999:7:::After
/etc/shadow:help:$6$rounds=5000$salt$hashed_password:18345:0:99999:7:::4.4 Security Practices Relevant to This Vulnerability
Practices that directly address this vulnerability type include least privilege and safe defaults. Least privilege reduces the impact if an account is compromised, while safe defaults prevent weak configurations from being used in production.
- Practice 1: Implement least privilege by granting accounts only the permissions they need to perform their tasks.
- Practice 2: Enforce strong password policies and require regular password changes.
4.5 Automation (Optional)
#!/bin/bash
# Script to disable the 'help' account on Linux systems
for host in ; do
ssh root@$host "userdel -r help"
echo "Disabled 'help' account on $host"
done
5. Verification / Validation
- Post-fix check: Attempt to SSH into the server using username ‘help’ and no password. Expected output should be “Permission denied”.
- Re-test: Re-run the quick check from section 3 to confirm login is now prevented without a valid password.
- Smoke test: Verify other administrative accounts can still log in as expected.
- Monitoring: Check system authentication logs for failed login attempts using the ‘help’ account, indicating successful mitigation.
ssh help@6. Preventive Measures and Monitoring
Update security baselines to include strong password requirements and regular account audits. Implement checks in CI/CD pipelines to prevent default accounts from being deployed with empty passwords.
- Baselines: Update your system hardening baseline (for example, CIS benchmarks) to require a strong password for all accounts, including ‘help’.
- Pipelines: Add static analysis tools to your CI/CD pipeline that scan for default credentials and weak configurations.
- Asset and patch process: Review system configurations regularly as part of an asset management or vulnerability scanning program.
7. Risks, Side Effects, and Roll Back
Disabling the ‘help’ account may impact applications relying on it. Setting a password incorrectly could lock out access. Roll back by restoring from backup or re-enabling the account with a default password if needed.
- Risk or side effect 2: Incorrectly setting the password could lock out access to the system. Ensure you have an alternative administrative account available.
- Roll back: Restore from backup if necessary. Alternatively, re-enable the ‘help’ account with a default password using
useradd help(Linux).
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 user management documentation for instructions on setting and changing passwords.