CVE-2026-28725

Executive Summary

CVE-2026-28725 is a sensitive information disclosure vulnerability affecting Acronis Cyber Protect 17 on both Linux and Windows platforms. The flaw arises from improper configuration of a headless browser component used within the product, potentially allowing an attacker to access sensitive data. The vulnerability has a CVSS score of 5.5 (Medium) and currently has no known public proof-of-concept or exploit code. The vendor has released a fix in build 41186.

CVSS Breakdown & Threat Level

• CVSS Score: 5.5 (Medium)
• Attack Vector: Local (AV:L)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

The medium severity rating reflects the local attack vector and low confidentiality impact. An attacker with local access to the system could exploit the misconfigured headless browser to leak sensitive information, but no remote exploitation is possible.

Deep Dive & Mechanics

The vulnerability is rooted in the improper configuration of a headless browser (likely Chromium-based) used by Acronis Cyber Protect for rendering or automation tasks. A headless browser, when misconfigured, can expose internal data, session tokens, or file system paths through its debugging or communication interfaces. In this case, the browser’s configuration allowed unintended access to sensitive information, such as credentials, configuration files, or internal API endpoints.

The affected component is part of the Acronis Cyber Protect 17 suite, which integrates backup, anti-malware, and endpoint management features. The headless browser is used for tasks like rendering reports or interacting with web-based management consoles. The misconfiguration likely involves exposing the browser’s remote debugging port (e.g., port 9222) or enabling verbose logging that leaks data to local users.

Vulnerable vs. Patched Code

No specific code diff is available, but the patch (build 41186) addresses the headless browser configuration. The vulnerable version likely had:

• Remote debugging enabled without authentication.
• Insecure command-line flags (e.g., --remote-debugging-port=0 or --enable-logging with sensitive data).
• Lack of sandboxing or process isolation.

The patched version restricts debugging access, disables verbose logging, and ensures the browser runs with minimal privileges.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Local access to a system running Acronis Cyber Protect 17 (build < 41186).
• Ability to execute commands or scripts on the target.

Exploitation Steps:

1. Identify the headless browser process (e.g., chrome or chromium).
2. Check for exposed debugging ports:

   netstat -tulpn | grep 9222
   

3. If a debugging port is open, connect to it using a WebSocket client:

   wscat -c ws://127.0.0.1:9222/devtools/browser/<id>
   

4. Use the DevTools Protocol to extract sensitive data:

   // Example: List all open tabs and their URLs
   {"id":1,"method":"Target.getTargets"}
   

5. Alternatively, check for log files containing sensitive information:

   cat /var/log/acronis/browser.log | grep -i "password\|token\|secret"
   

Blue Team

Detection Steps:

1. Monitor for unexpected headless browser processes:

   ps aux | grep -i "headless\|--remote-debugging"
   

2. Check for open debugging ports:

   netstat -tulpn | grep 9222
   

3. Review browser logs for sensitive data leakage:

   grep -r "password\|token\|secret" /var/log/acronis/
   

4. Verify the Acronis Cyber Protect build version:

   acronis-cyber-protect --version
   

Indicators of Compromise (IOCs)

• Process: chrome --headless --remote-debugging-port=9222
• Network: Local connections to 127.0.0.1:9222
• File: Browser log files containing sensitive strings (e.g., password, token)
• Registry (Windows): HKLM\SOFTWARE\Acronis\CyberProtect\Browser\DebugPort

Detection Engineering

YARA Rule

rule CVE_2026_28725_Acronis_Headless_Browser {
    meta:
        description = "Detects Acronis Cyber Protect headless browser misconfiguration"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-28725"
    strings:
        $s1 = "--remote-debugging-port" ascii wide nocase
        $s2 = "--headless" ascii wide nocase
        $s3 = "Acronis Cyber Protect" ascii wide nocase
    condition:
        all of them
}

Sigma Rule

title: Acronis Cyber Protect Headless Browser Misconfiguration
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects headless browser processes with debugging enabled on Acronis Cyber Protect
author: Valters IT
date: 2026-01-01
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-28725
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\chrome.exe'
        CommandLine|contains|all:
            - '--headless'
            - '--remote-debugging-port'
    condition: selection
falsepositives:
    - Legitimate debugging sessions
level: medium

Suricata Rule

alert tcp $HOME_NET any -> $HOME_NET 9222 (msg:"CVE-2026-28725 Acronis Headless Browser Debug Port"; flow:to_server; content:"WebSocket"; nocase; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade Acronis Cyber Protect 17 to build 41186 or later.
2. If upgrade is not possible, restrict local access to the system.
3. Disable the headless browser feature if not required.

Long-Term Measures:

• Implement application whitelisting to prevent unauthorized processes.
• Monitor for exposed debugging ports using network security tools.
• Conduct regular vulnerability scans for Acronis products.

Workarounds:

• Use firewall rules to block local connections to port 9222.
• Set environment variables to disable debugging:

  export CHROME_HEADLESS=--no-sandbox --disable-logging
  

Valters IT
Securing Digital Frontiers