Why doesn’t CDR detect the JavaScript I appended to a PDF file?

This article applies to all MetaDefender Core releases deployed on Windows and Linux systems.

Cause

If the JavaScript-containing objects are added to the PDF but the Xref (Cross-Reference) table is not updated accordingly, CDR will not detect them.

  • The Xref table is crucial for referencing valid objects in a PDF.
  • Objects missing from the Xref table are considered garbage data and will be removed by the CDR engine.

Solution

To ensure that JavaScript in a PDF is detected by CDR:

  1. Update the Xref Table:
  • When adding JavaScript, ensure that the corresponding object is correctly referenced in the Xref table.
  1. Follow PDF File Structure Specifications:
  • The JavaScript should be stored in a properly structured and up-to-date object within the PDF.

Conclusion

For JavaScript to be recognised in a PDF by CDR, it must be placed in a valid object that is correctly indexed in the Xref table and complies with the PDF file structure specifications.

If Further Assistance is required, please proceed to log a support case or chatting with our support engineer.
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