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How to remediate – HTML Object

Contents

1. Introduction

The vulnerability is an HTML Object tag detected in web pages. This tag allows embedding multimedia content, but can be misused to deliver malicious code. Businesses should address this as it could lead to cross-site scripting (XSS) attacks and compromise user data or system integrity. Affected systems are typically web servers and any applications that generate dynamic HTML content. Likely impact is medium on confidentiality, integrity, and availability.

2. Technical Explanation

The vulnerability arises from the use of the `` tag in HTML. Attackers can exploit this by embedding malicious applets or other executable content within the object tag’s data source. This requires a user to visit a web page containing the crafted HTML object. There is no specific CVE associated with simply *using* the tag, but exploitation depends on vulnerabilities within the embedded objects themselves. For example, an outdated Java applet could be exploited through this vector.

  • Root cause: The scanner detected one or more HTML object tags which can potentially load untrusted content.
  • Exploit mechanism: An attacker crafts a malicious HTML page containing an `` tag pointing to a compromised resource, such as a Java applet with known vulnerabilities. When a user visits the page, the browser attempts to load and execute the embedded content.
  • Scope: Web servers serving dynamic HTML content are affected. The specific scope depends on the type of object being loaded (e.g., Java, Flash, PDF).

    • 3. Detection and Assessment

    Confirming vulnerability involves identifying instances of the `` tag in web pages. A quick check is to review HTML source code for the presence of this tag. Thorough assessment requires analyzing the content being loaded by these tags.

    • Quick checks: Use a text editor or browser developer tools to search for `` tags within HTML files served by your web server.
    • Scanning: Nessus, OpenVAS and other vulnerability scanners may flag HTML object tags as informational findings. These are examples only.
    • Logs and evidence: Web server access logs can show requests for the objects being loaded. Look for unusual file extensions or content types associated with `` tag references.
      grep -i "<object>" /path/to/your/html/files/*

      4. Solution / Remediation Steps

      Fixing the issue involves reviewing and removing unnecessary HTML object tags. If necessary, ensure that any remaining objects are legitimate and secure.

      4.1 Preparation

      • Dependencies: None. Roll back plan: Restore the backed-up HTML files.
      • Change window needs: A standard change window may be required, depending on your organization’s policies. Approval from a security team member is recommended.

      4.2 Implementation

      1. Step 1: Review all web pages for instances of the `` tag.
      2. Step 2: If an object tag is not required, remove it from the HTML source code.
      3. Step 3: If an object tag is necessary, verify that the embedded content is legitimate and secure (e.g., up-to-date Java applet).
      4. Step 4: Repeat steps 1-3 for all web pages served by your server.

        5. 4.3 Config or Code Example

        Before

        <object type="application/java-applet" width="500" height="300" codebase="http://example.com/applet.jar">
  <param name="script" value="myApplet.class">
</object>

        After

        4.4 Security Practices Relevant to This Vulnerability

        Several security practices can help mitigate this vulnerability type. Least privilege reduces impact if exploited, while input validation prevents unsafe data from being processed. Safe defaults and a regular patch cadence ensure that embedded content remains secure.

        • Practice 1: Least privilege – limit the permissions of web server processes to reduce potential damage from compromised objects.
        • Practice 2: Input validation – sanitize any user-supplied data used in generating HTML pages to prevent injection attacks.

        4.5 Automation (Optional)

        A simple script can be used to search for and report instances of the `` tag across multiple files.

        #!/bin/bash
find /path/to/your/html/files -type f -name "*.html" | xargs grep -i "<object>"

        5. Verification / Validation

        Confirm the fix by verifying that all unnecessary HTML object tags have been removed and any remaining objects are secure. Re-run the earlier detection method to confirm no tags remain.

        • Post-fix check: Run the `grep` command from step 3 of Detection and Assessment. The output should be empty if all instances of the `` tag have been removed or secured.
        • Re-test: Repeat the quick check to confirm that no `` tags are present in your HTML files.
        • Monitoring: Monitor web server logs for any new requests associated with the removed objects.
          • grep -i "<object>" /path/to/your/html/files/* (Expected output: empty)

          6. Preventive Measures and Monitoring

          Update security baselines to disallow unnecessary HTML object tags. Add checks in CI or deployment pipelines to scan for potentially unsafe content. Implement a regular patch review cycle for any embedded objects.

          • Baselines: Update your web server’s security baseline to restrict the use of `` tags unless explicitly required and approved.
          • Pipelines: Add Static Application Security Testing (SAST) tools to your CI pipeline to scan HTML files for potentially unsafe content, including `` tags.
          • Asset and patch process: Establish a regular review cycle for any embedded objects used in your web applications to ensure they are up-to-date and secure.

            • 7. Risks, Side Effects, and Roll Back