1. Introduction
The ArubaOS-Switch DoS vulnerability (ARUBA-PSA-2021-002) affects certain HPE and Aruba L2/L3 switches. It allows a remote attacker with administrator privileges to crash or reboot the switch management interface, causing a local denial of service. This could disrupt network connectivity for devices connected to the affected switch. The vulnerability impacts availability.
2. Technical Explanation
This vulnerability is caused by a data processing error in the switch’s management interface when handling unexpected data types in user-supplied information. An attacker with administrator access can exploit this flaw to trigger a crash or reboot of the switch’s management interface, potentially leading to a full switch DoS. The CVE associated with this issue is CVE-2021-25141.
- Root cause: Improper handling of unexpected data types in user supplied information to the switch’s management interface.
- Exploit mechanism: An attacker must supply malicious input to the switch’s management interface with administrator privileges. This could be achieved through a crafted configuration or command.
- Scope: HPE and Aruba L2/L3 switches running vulnerable firmware versions.
3. Detection and Assessment
You can check if your systems are vulnerable by verifying the installed firmware version. Nessus relies on self-reported version numbers for detection.
- Quick checks: Use the switch’s command-line interface (CLI) to show the current firmware version. For example, use a command like
show version. - Scanning: Nessus can be used with the plugin ID related to ARUBA-PSA-2021-002 as an example.
- Logs and evidence: Check switch logs for crashes or reboots around the time of suspicious activity, though this is not a reliable indicator on its own.
show version4. Solution / Remediation Steps
Apply the firmware update provided by HPE/Aruba to address this vulnerability.
4.1 Preparation
- Stopping services is not required for this update, but plan for potential downtime during the reboot. A roll back plan involves restoring from the backup configuration.
- A change window may be needed depending on business impact. Approval from network administrators is recommended.
4.2 Implementation
- Step 1: Download the latest firmware version for your switch model from the HPE/Aruba support website.
- Step 2: Upload the firmware file to the switch using a secure method (e.g., SCP, TFTP).
- Step 3: Install the new firmware using the switch’s CLI command for firmware upgrades. For example, use a command like
upgrade image. - Step 4: Reboot the switch to activate the new firmware.
4.3 Config or Code Example
Before
show version (check current vulnerable firmware)After
show version (check updated firmware version after upgrade)4.4 Security Practices Relevant to This Vulnerability
Practices that can help prevent this issue include least privilege access and a regular patch cadence.
- Practice 1: Least privilege access limits the potential impact if an attacker gains access to the switch.
- Practice 2: A regular patch cadence ensures timely application of security updates, reducing the window of opportunity for exploitation.
4.5 Automation (Optional)
Automation is not generally available for this specific firmware upgrade process and should be approached with caution.
5. Verification / Validation
Confirm that the new firmware version has been installed successfully and that the vulnerability is no longer present.
- Post-fix check: Run
show versionagain to verify the updated firmware version. - Smoke test: Verify basic network connectivity by pinging devices through the switch.
- Monitoring: Monitor switch logs for any unexpected crashes or reboots, though this is not a direct indicator of vulnerability status.
show version (verify updated firmware)6. Preventive Measures and Monitoring
Update your security baselines to include the latest recommended firmware versions for HPE/Aruba switches. Implement regular patch management processes.
- Baselines: Update your switch configuration baseline to reflect the minimum acceptable firmware version.
- Asset and patch process: Implement a regular schedule for reviewing and applying security patches to all network devices.
7. Risks, Side Effects, and Roll Back
- Risk or side effect 1: Firmware upgrade may temporarily interrupt network connectivity during the reboot process.
- Risk or side effect 2: In rare cases, a firmware upgrade could introduce new bugs or compatibility issues.
8. References and Resources
Refer to official HPE/Aruba documentation for more information.
- Vendor advisory or bulletin: https://www.arubanetworks.com/assets/alert/ARUBA-PSA-2021-002.txt
- NVD or CVE entry: CVE-2021-25141