1. Introduction
Acronis Agent Detection (TCP) refers to a backup service listening on a remote host. This indicates that Acronis TrueImage is installed, which manages backup and restore operations. While not directly exploitable, open ports can increase the attack surface of a system. Confidentiality, integrity, and availability could be impacted if an attacker gains access to the Acronis Agent.
2. Technical Explanation
The remote service is an Acronis Agent component used for managing backups. The agent listens on TCP ports to accept connections from the Acronis management console or other agents. This vulnerability isn’t a flaw in the software itself, but rather the exposure of a listening service. An attacker could attempt to exploit vulnerabilities within the Acronis Agent software if they gain access to the network and port.
- Root cause: The Acronis Agent is running and listening on a TCP port.
- Exploit mechanism: An attacker could scan for open ports, identify the Acronis Agent service, and attempt to exploit known vulnerabilities in the agent software.
- Scope: Windows systems with Acronis TrueImage installed are affected.
3. Detection and Assessment
You can confirm if a system is vulnerable by checking for the listening port or identifying the running Acronis Agent service.
- Quick checks: Use
netstat -an | findstr "81"to check for connections on TCP port 81, which is commonly used by Acronis Agents. - Scanning: Nessus or other vulnerability scanners may identify the open Acronis Agent service with signature ID 93675 (example only).
- Logs and evidence: Check Windows Event Logs for events related to the Acronis Agent installation or activity.
netstat -an | findstr "81"4. Solution / Remediation Steps
Limit incoming traffic to this port if desired, especially in environments where remote access is not required.
4.1 Preparation
- Ensure you have administrative credentials for the target system. A roll back plan involves restoring the system from backup or restarting the Acronis Agent service.
- A change window may be needed depending on your environment and impact assessment. Approval from a security team might be required.
4.2 Implementation
- Step 1: Configure the Windows Firewall to block incoming traffic on TCP port 81.
- Step 2: Verify that the firewall rule is active and blocking connections.
4.3 Config or Code Example
Before
No specific firewall rule exists for port 81.After
netsh advfirewall firewall add rule name="Block Acronis Agent Port 81" dir=in action=block protocol=TCP localport=814.4 Security Practices Relevant to This Vulnerability
Least privilege and network segmentation can reduce the impact of exposed services like this one.
- Practice 1: Least privilege – only allow necessary access to ports and services.
- Practice 2: Network segmentation – isolate sensitive systems from untrusted networks.
4.5 Automation (Optional)
A PowerShell script can be used to automate the firewall rule creation across multiple systems.
# Example PowerShell Script
$ruleName = "Block Acronis Agent Port 81"
netsh advfirewall firewall add rule name="$ruleName" dir=in action=block protocol=TCP localport=815. Verification / Validation
Confirm the fix by checking if the port is blocked and re-running the detection method.
- Post-fix check: Run
netstat -an | findstr "81"again; no connections should be shown on TCP port 81. - Re-test: Re-run the initial quick check (
netstat -an | findstr "81") to confirm the port is no longer listening. - Monitoring: Monitor Windows Firewall logs for blocked connections on TCP port 81 as an example of regression detection.
netstat -an | findstr "81"6. Preventive Measures and Monitoring
Regular security baselines and vulnerability scanning can help identify exposed services like this one.
- Baselines: Update a security baseline to include firewall rules for unnecessary ports.
- Pipelines: Add checks in CI or deployment pipelines to ensure that only necessary ports are open.
- Asset and patch process: Implement a regular asset inventory and vulnerability scanning schedule.
7. Risks, Side Effects, and Roll Back
Blocking the port may prevent remote access to the Acronis Agent service if required.
- Risk or side effect 1: Blocking the port may disrupt backup operations that rely on remote access.
- Roll back: Remove the firewall rule using
netsh advfirewall firewall delete rule name="Block Acronis Agent Port 81"and restart the Acronis Agent service if necessary.
8. References and Resources
- Vendor advisory or bulletin: http://www.acronis.com/enterprise/products/ATIES/windows-agent.html
- NVD or CVE entry: Not applicable, as this is not a specific vulnerability but an exposure risk.
- Product or platform documentation relevant to the fix: http://www.acronis.com/enterprise/products/ATIES/windows-agent.html