How to remediate – Adobe Flash Media Server Version Detection

1. Introduction

Adobe Flash Media Server Version Detection refers to the reporting of version information in HTTP headers by Adobe Flash Media Server, a server used for delivering applications to Flash Player. This can allow attackers to identify systems running vulnerable versions of the software and target them with exploits. Affected systems typically include web servers hosting Flash-based content or streaming media services. A successful exploit could lead to information disclosure, denial of service, or remote code execution.

2. Technical Explanation

The vulnerability occurs because Adobe Flash Media Server unnecessarily exposes its version number in HTTP headers during normal operation. An attacker can passively scan for this information to identify potential targets. While a specific CVE isn’t directly associated with *reporting* the version, it highlights the risk of running unsupported or vulnerable versions. Exploitation typically involves identifying the server and then attempting known exploits against that version of Flash Media Server.

• Root cause: Unnecessary exposure of software version in HTTP headers.
• Exploit mechanism: An attacker uses tools like `curl` or a web browser’s developer tools to inspect HTTP responses for the server header containing the version number. This information is then used to target known vulnerabilities. For example, an attacker could identify a server running an older version of Flash Media Server and attempt to exploit a remote code execution vulnerability associated with that version.
• Scope: Adobe Flash Media Server versions are affected.

3. Detection and Assessment

You can confirm if a system is vulnerable by checking the HTTP headers returned when accessing a web server hosting content served by Flash Media Server. A thorough method involves using a network scanner to identify systems running Flash Media Server and then inspecting their HTTP responses.

• Quick checks: Use `curl -I ` or inspect the response headers in your browser’s developer tools (Network tab). Look for the “Server” header containing “Adobe Flash Media Server”.
• Scanning: Nessus plugin ID 16398 can identify Adobe Flash Media Server and report its version. OpenVAS also has relevant scan queries. These are examples only, as scanner coverage varies.
• Logs and evidence: Web server access logs may show requests to resources served by Flash Media Server. Look for patterns indicating the server’s presence.

curl -I https://example.com/flashapp

4. Solution / Remediation Steps

The primary solution is to disable unnecessary HTTP header reporting or, ideally, decommission Adobe Flash Media Server if it’s no longer required. If the server must remain active, ensure it’s running the latest supported version and apply all available security patches.

4.1 Preparation

• Ensure you have access credentials for the web server and Flash Media Server administration console. A roll back plan involves restoring the original web server configuration.
• A change window may be required, depending on your organization’s policies. Approval from a system administrator is recommended.

4.2 Implementation

1. Step 1: Access the Adobe Flash Media Server administration console.
2. Step 2: Locate the settings related to HTTP header reporting (this varies by version and configuration).
3. Step 3: Disable or remove the server version information from the headers, if possible.
4. Step 4: Restart the Adobe Flash Media Server service for changes to take effect.

4.3 Config or Code Example

Before

Server: Adobe Flash Media Server 5.0.1

After

Server: Apache/2.4.41 (Ubuntu)  # Example - header modified to show web server only. Actual result depends on configuration.

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help mitigate this vulnerability type. Least privilege limits the impact of successful exploits. Input validation prevents attackers from injecting malicious data. Safe defaults reduce the attack surface by minimizing unnecessary features and information disclosure. Regular patch cadence ensures systems are running the latest security updates.

• Practice 1: Least privilege to limit potential damage if exploited.
• Practice 2: Patching to address known vulnerabilities in Adobe Flash Media Server.

4.5 Automation (Optional)

Automation is difficult without specific configuration details for each installation of Adobe Flash Media Server. However, you could use a script to periodically scan web servers for the presence of the “Adobe Flash Media Server” header and alert administrators if it’s detected.

# Example PowerShell Script (requires appropriate permissions)
$urls = @("https://example.com/flashapp", "https://anotherdomain.com/stream")
foreach ($url in $urls) {
  $response = Invoke-WebRequest -Uri $url -UseBasicParsing
  if ($response.Headers["Server"] -like "*Adobe Flash Media Server*") {
    Write-Host "Vulnerable server found: $url"
  }
}

5. Verification / Validation

Confirm the fix by rechecking the HTTP headers returned when accessing the web server. The “Server” header should no longer contain “Adobe Flash Media Server” or, if it does, should not reveal specific version information. A simple service smoke test involves verifying that Flash-based content still loads correctly.

• Post-fix check: Run `curl -I ` again. The “Server” header should be modified to remove the Adobe Flash Media Server version string, or show only the web server information.
• Re-test: Repeat the initial detection method (browser developer tools) and confirm that the vulnerability is no longer present.
• Monitoring: Monitor web server logs for any errors or unexpected behavior related to Flash Media Server.

curl -I https://example.com/flashapp # Expected output: No "Adobe Flash Media Server" in headers.

6. Preventive Measures and Monitoring

Update security baselines to include a check for unnecessary HTTP header reporting. Implement checks in CI or deployment pipelines (SAST, SCA) to identify systems running vulnerable versions of Adobe Flash Media Server. Establish a sensible patch or configuration review cycle that fits the risk profile of your organization.

• Baselines: Update security baselines to prohibit exposing software version information in HTTP headers.
• Pipelines: Add checks for known vulnerabilities during deployment.
• Asset and patch process: Review Flash Media Server configurations regularly as part of a vulnerability management program.

7. Risks, Side Effects, and Roll Back

• Risk or side effect 1: Compatibility issues with legacy Flash applications. Mitigation: Test thoroughly in a non-production environment.
• Roll back: Restore the web server configuration from your backup. Restart the web server service.

8. References and Resources

• Vendor advisory or bulletin: