1. Introduction
The Nortel Networks Router Unpassworded Account (User Level) vulnerability allows unauthenticated access to a remote Telnet service. This means anyone on the network can potentially gain control of your router without needing a username or password. It affects routers from Nortel Networks, previously Bay Networks. Successful exploitation could compromise confidentiality, integrity and availability by allowing an attacker to reconfigure the router, block legitimate traffic, and disrupt network operations.
2. Technical Explanation
The vulnerability occurs because the default ‘User’ account on the Telnet service has no password set. An attacker can connect to the Telnet port (typically 23) and gain access with an empty username and password. This allows full administrative control of the router. There is currently no publicly assigned CVE for this specific issue, but it’s a common misconfiguration. For example, an attacker could use a basic Telnet client to connect to the router without providing credentials. Affected systems include Nortel Networks routers running firmware where the default ‘User’ account remains active with no password.
- Root cause: The remote Telnet service allows login using the ‘User’ account without requiring a password.
- Exploit mechanism: An attacker connects to the router via Telnet and attempts to log in with an empty username and password, gaining access. Example payload: simply connecting to the router’s IP address on port 23 without credentials.
- Scope: Nortel Networks (formerly Bay Networks) routers are affected. Specific versions depend on firmware configurations.
3. Detection and Assessment
You can confirm this vulnerability by attempting a Telnet connection to the router with no username or password. A more thorough assessment involves reviewing the router’s configuration for accounts without passwords.
- Quick checks: Use `show system information` via CLI (if accessible) to check the firmware version and if Telnet is enabled.
- Scanning: Nessus plugin ID 10874 can detect this issue, but results should be manually verified.
- Logs and evidence: Check router logs for successful logins from unknown sources using the ‘User’ account. Log locations vary by model; consult your device documentation.
telnet <router_ip> 234. Solution / Remediation Steps
Set a strong password for the ‘User’ account on the router to prevent unauthorized access. Follow these steps carefully to avoid disrupting network connectivity.
4.1 Preparation
- Stopping services is not usually required for this change, but plan a maintenance window in case of unexpected issues. A roll back plan involves restoring the backed-up configuration.
- Changes should be approved by a senior network administrator.
4.2 Implementation
- Step 1: Connect to the router via console or Telnet (if possible).
- Step 2: Enter configuration mode using the appropriate command (e.g., `configure`).
- Step 3: Navigate to the ‘User’ account settings. The exact commands vary by model, but typically involve a command like `user User`.
- Step 4: Set a strong password for the ‘User’ account using the `password <new_password>` command.
- Step 5: Save the configuration using the appropriate command (e.g., `write memory`).
4.3 Config or Code Example
Before
user User
password ""
After
user User
password <strong_password>
4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this type of issue. Least privilege reduces the impact if an account is compromised. Safe defaults ensure accounts start with strong passwords or are disabled by default. Regular patch cadence ensures known vulnerabilities are addressed quickly.
- Practice 1: Implement least privilege to limit access rights for all user accounts, reducing potential damage from a compromise.
- Practice 2: Enforce safe defaults by requiring strong passwords for all new accounts or disabling default accounts that aren’t needed.
4.5 Automation (Optional)
Automation is not generally recommended for this specific issue due to the risk of locking yourself out. However, configuration management tools can be used to enforce password policies across multiple devices.
# Example Ansible task - use with caution!
- name: Set user password (example only)
command: "configure terminal; user User; password <strong_password>; write memory"
when: ansible_netapp_user == 'User' and ansible_netapp_password == ''
5. Verification / Validation
- Post-fix check: Attempt to Telnet to the router using an empty username and password; access should be denied.
- Re-test: Repeat the initial Telnet connection attempt from Section 3; it should now fail.
- Smoke test: Verify you can still ping the router and access any critical services it provides.
- Monitoring: Monitor router logs for failed login attempts using the ‘User’ account, which could indicate ongoing attacks.
telnet <router_ip> 23
Trying <router_ip> ...
Connected to <router_ip>.
Login: (Access denied message should appear)
6. Preventive Measures and Monitoring
Update your security baseline or policy to include requirements for strong passwords on all network devices. Implement checks in CI/CD pipelines to prevent configurations with default accounts or weak passwords from being deployed. Establish a sensible patch or configuration review cycle that fits the risk profile of your network. For example, regular vulnerability scans and penetration tests can identify misconfigurations like this one.
- Baselines: Update security baselines to include strong password requirements for all router accounts.
- Pipelines: Add checks in CI/CD pipelines to scan configurations for default passwords or weak credentials.
- Asset and patch process: Implement a regular configuration review cycle (e.g., quarterly) to identify and remediate misconfigurations.
7. Risks, Side Effects, and Roll Back
- Risk or side effect 1: Incorrect password entry can lead to loss of access; double check your input.
- Risk or side effect 2: Configuration errors could disrupt network connectivity; have a roll back plan ready.
- Roll back:
- Step 1: Restore the router’s configuration from the backup created in Section 4.1.