1. Introduction
The Cisco SD-WAN Solution vManage Cross-Site Request Forgery (CSRF) vulnerability (CVE-2019-16002) allows an unauthenticated, remote attacker to perform actions with the privilege level of a logged-in user. This matters because it could allow attackers to change system configurations or access sensitive data. Systems running affected versions of Cisco SD-WAN Solution vManage are at risk. A successful exploit could compromise confidentiality, integrity, and availability depending on the privileges of the exploited user.
2. Technical Explanation
The vulnerability is due to missing CSRF protections in the web UI of Cisco SD-WAN Solution vManage. An attacker can exploit this by persuading a user to follow a malicious link. This allows them to perform actions on behalf of that user without their knowledge. The vulnerability affects versions of vManage as referenced in cisco-sa-20191120-vman-csrf.
- Root cause: Insufficient CSRF protections for the web UI, allowing arbitrary requests from unauthenticated sources.
- Exploit mechanism: An attacker crafts a malicious HTML page containing a request to vManage with the user’s session cookie. When the victim visits the page while logged in, the request is executed as if initiated by the user.
- Scope: Cisco SD-WAN Solution vManage. Affected versions are detailed in cisco-sa-20191120-vman-csrf.
3. Detection and Assessment
- Quick checks: Check the vManage web UI for the software version under ‘Administration > Software Versions’.
- Scanning: Nessus may report this issue based on self-reported version numbers. Other scanners might have signatures related to CSRF vulnerabilities in Cisco products, but testing is not guaranteed.
- Logs and evidence: Review vManage logs for suspicious requests originating from unexpected sources or patterns indicative of cross-site request forgery attempts. Specific log files are not publicly documented.
4. Solution / Remediation Steps
Apply the security patch as described in the Cisco advisory.
4.1 Preparation
- No services need to be stopped, but plan for a maintenance window as the system may require a restart. Roll back by restoring the backup or reverting the snapshot.
- Changes should be approved according to your organization’s change management process.
4.2 Implementation
- Step 1: Download the appropriate patch from Cisco Software Downloads (requires valid support contract).
- Step 2: Install the patch following the instructions in cisco-sa-20191120-vman-csrf. This typically involves uploading the patch through the vManage web UI or using a command-line interface.
4.3 Config or Code Example
Before
After
4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this type of vulnerability.
- Practice 1: Least privilege – Limit user privileges to only what is necessary, reducing the impact if an account is compromised.
- Practice 2: Input validation – Implement strict input validation on all web-based forms and requests to prevent malicious data from being processed.
4.5 Automation (Optional)
Automation of patch deployment depends on your environment and tools.
5. Verification / Validation
Confirm that the patch has been applied successfully and the vulnerability is no longer present.
- Post-fix check: Verify the software version in the vManage web UI (Administration > Software Versions) to confirm the updated version is installed.
- Smoke test: Verify that core vManage functionality, such as device monitoring and configuration management, continues to operate normally.
- Monitoring: Monitor vManage logs for any suspicious activity related to cross-site requests.
6. Preventive Measures and Monitoring
Implement security baselines and monitoring practices.
- Baselines: Update your security baseline to include the latest Cisco security recommendations for SD-WAN Solution vManage.
- Pipelines: Integrate vulnerability scanning into your CI/CD pipeline to identify potential CSRF vulnerabilities during development.
- Asset and patch process: Establish a regular patch review cycle for all critical systems, including Cisco devices, to ensure timely application of security updates.
7. Risks, Side Effects, and Roll Back
Applying the patch may cause temporary service disruption.
- Risk or side effect 1: Patch installation could temporarily interrupt vManage services. Plan for a maintenance window.
8. References and Resources
- Vendor advisory or bulletin: http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20191120-vman-csrf
- NVD or CVE entry: CVE-2019-16002
- Product or platform documentation relevant to the fix: https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvo19118