How to remediate – ActiveFax Server Detection

1. Introduction

ActiveFax Server Detection indicates a fax server is running on this host. This matters because fax servers can be targets for attackers seeking sensitive data or using them to send malicious faxes. Systems typically affected are Windows servers running ActiveFax software. A compromised fax server could lead to confidentiality, integrity and availability loss through unauthorized access, data breaches, or denial of service.

2. Technical Explanation

ActiveFax Server is a fax processing application for Windows. The presence of the server indicates that the host is capable of sending and receiving faxes. While not directly exploitable in itself, it presents an attack surface. There are no known CVEs associated with simply *detecting* ActiveFax; however, vulnerabilities may exist within the software itself. An attacker could attempt to exploit weaknesses in the fax server application to gain unauthorized access or control of the system. Affected platforms include Windows servers running ActiveFax Server.

• Root cause: The presence of the ActiveFax service indicates a potential vulnerability point.
• Exploit mechanism: An attacker could attempt to exploit known vulnerabilities in the ActiveFax software, such as buffer overflows or injection flaws, to gain control of the server.
• Scope: Windows servers running ActiveFax Server are affected.

3. Detection and Assessment

To confirm whether a system is vulnerable, first check for the presence of the ActiveFax service. Then review installed software versions.

• Quick checks: Use PowerShell to list installed services and identify ActiveFax Server.
• Scanning: Nessus plugin ID 139840 can detect ActiveFax Server. This is an example only.
• Logs and evidence: Check the Windows Event Logs for events related to ActiveFax, specifically in the Application log.

Get-Service | Where-Object {$_.DisplayName -like "*ActiveFax*"}

4. Solution / Remediation Steps

The following steps outline how to remediate the detection of ActiveFax Server. These steps assume that removing the service is acceptable; if it’s required, see section 7 for risks.

4.1 Preparation

• Dependencies: Ensure no critical applications rely on ActiveFax functionality. A roll back plan involves restoring from backup.
• Change window: Coordinate with stakeholders and obtain approval for service removal, if required.

4.2 Implementation

1. Step 1: Open the Services app (services.msc).
2. Step 2: Locate the “ActiveFax Server” service.
3. Step 3: Right-click on the service and select “Properties”.
4. Step 4: Set the Startup type to “Disabled”.
5. Step 5: Click “Apply”, then “OK”.

4.3 Config or Code Example

Before

Startup type: Automatic (Delayed Start)

After

Startup type: Disabled

4.4 Security Practices Relevant to This Vulnerability

Practices that directly address this vulnerability include least privilege and regular security assessments.

• Practice 1: Least privilege helps limit the impact if ActiveFax is exploited by ensuring it only has necessary permissions.
• Practice 2: Regular security assessments identify potential vulnerabilities like outdated software or misconfigurations.

4.5 Automation (Optional)

# PowerShell script to disable ActiveFax service
Get-Service | Where-Object {$_.DisplayName -like "*ActiveFax*"} | Set-Service -StartupType Disabled

5. Verification / Validation

Confirm the fix by checking that the ActiveFax service is disabled and no longer running. Then, re-run the initial detection method to verify it’s gone.

• Post-fix check: Run `Get-Service | Where-Object {$_.DisplayName -like “*ActiveFax*”}`. Expected output should be empty.
• Re-test: Re-run the earlier detection (PowerShell command) to confirm ActiveFax is no longer listed.
• Smoke test: Verify any applications that previously relied on fax functionality are still working as expected, or have been appropriately decommissioned.
• Monitoring: Monitor Windows Event Logs for unexpected events related to fax services.

Get-Service | Where-Object {$_.DisplayName -like "*ActiveFax*"}

6. Preventive Measures and Monitoring

Preventive measures include updating security baselines and incorporating vulnerability scanning into CI/CD pipelines.

• Baselines: Update a security baseline to disallow the installation of unnecessary fax server software.
• Pipelines: Add checks in CI or deployment to scan for known vulnerabilities in installed software, including ActiveFax.
• Asset and patch process: Implement a regular review cycle for installed software to identify and remove unused applications like ActiveFax.

7. Risks, Side Effects, and Roll Back

Removing ActiveFax may impact any applications or processes that rely on its functionality. The roll back steps involve restoring the service configuration.

• Risk or side effect 1: Disabling ActiveFax could break fax-dependent workflows.
• Risk or side effect 2: Unexpected application behavior if other services relied on ActiveFax components.
• Roll back:
  1. Step 1: Open the Services app (services.msc).
  2. Step 2: Locate the “ActiveFax Server” service.
  3. Step 3: Right-click on the service and select “Properties”.
  4. Step 4: Set the Startup type to “Automatic” or its original setting.
  5. Step 5: Click “Apply”, then “OK”.

8. References and Resources

• Vendor advisory or bulletin: http://www.actfax.com/