Hướng dẫn cho người dùng Hủy

Security warnings when a PDF opens

  1. Acrobat User Guide
  2. Introduction to Acrobat
    1. Access Acrobat from desktop, mobile, web
    2. Introducing the new Acrobat experience
    3. What's new in Acrobat
    4. Keyboard shortcuts
    5. System Requirements
  3. Workspace
    1. Workspace basics
    2. Opening and viewing PDFs
      1. Opening PDFs
      2. Navigating PDF pages
      3. Viewing PDF preferences
      4. Adjusting PDF views
      5. Enable thumbnail preview of PDFs
      6. Display PDF in browser
    3. Working with online storage accounts
      1. Access files from Box
      2. Access files from Dropbox
      3. Access files from OneDrive
      4. Access files from SharePoint
      5. Access files from Google Drive
    4. Acrobat and macOS
    5. Acrobat notifications
    6. Grids, guides, and measurements in PDFs
    7. Asian, Cyrillic, and right-to-left text in PDFs
  4. Creating PDFs
    1. Overview of PDF creation
    2. Create PDFs with Acrobat
    3. Create PDFs with PDFMaker
    4. Using the Adobe PDF printer
    5. Converting web pages to PDF
    6. Creating PDFs with Acrobat Distiller
    7. Adobe PDF conversion settings
    8. PDF fonts
  5. Editing PDFs
    1. Edit text in PDFs
    2. Edit images or objects in a PDF
    3. Rotate, move, delete, and renumber PDF pages
    4. Edit scanned PDFs
    5. Enhance document photos captured using a mobile camera
    6. Optimizing PDFs
    7. PDF properties and metadata
    8. Links and attachments in PDFs
    9. PDF layers
    10. Page thumbnails and bookmarks in PDFs
    11. PDFs converted to web pages
    12. Setting up PDFs for a presentation
    13. PDF articles
    14. Geospatial PDFs
    15. Applying actions and scripts to PDFs
    16. Change the default font for adding text
    17. Delete pages from a PDF
  6. Scan and OCR
    1. Scan documents to PDF
    2. Enhance document photos
    3. Troubleshoot scanner issues when scanning using Acrobat
  7. Forms
    1. PDF forms basics
    2. Create a form from scratch in Acrobat
    3. Create and distribute PDF forms
    4. Fill in PDF forms
    5. PDF form field properties
    6. Fill and sign PDF forms
    7. Setting action buttons in PDF forms
    8. Publishing interactive PDF web forms
    9. PDF form field basics
    10. PDF barcode form fields
    11. Collect and manage PDF form data
    12. About forms tracker
    13. PDF forms help
    14. Send PDF forms to recipients using email or an internal server
  8. Combining files
    1. Combine or merge files into single PDF
    2. Rotate, move, delete, and renumber PDF pages
    3. Add headers, footers, and Bates numbering to PDFs
    4. Crop PDF pages
    5. Add watermarks to PDFs
    6. Add backgrounds to PDFs
    7. Working with component files in a PDF Portfolio
    8. Publish and share PDF Portfolios
    9. Overview of PDF Portfolios
    10. Create and customize PDF Portfolios
  9. Sharing, reviews, and commenting
    1. Share and track PDFs online
    2. Mark up text with edits
    3. Preparing for a PDF review
    4. Starting a PDF review
    5. Hosting shared reviews on SharePoint or Office 365 sites
    6. Participating in a PDF review
    7. Add comments to PDFs
    8. Adding a stamp to a PDF
    9. Approval workflows
    10. Managing comments | view, reply, print
    11. Importing and exporting comments
    12. Tracking and managing PDF reviews
  10. Saving and exporting PDFs
    1. Saving PDFs
    2. Convert PDF to Word
    3. Convert PDF to PPTX
    4. Convert PDF to XLSX or XML
    5. Convert PDF to JPG
    6. Convert PDF to PNG
    7. Convert or export PDFs to other file formats
    8. File format options for PDF export
    9. Reusing PDF content
  11. Security
    1. Enhanced security setting for PDFs
    2. Securing PDFs with passwords
    3. Manage Digital IDs
    4. Securing PDFs with certificates
    5. Opening secured PDFs
    6. Removing sensitive content from PDFs
    7. Setting up security policies for PDFs
    8. Choosing a security method for PDFs
    9. Security warnings when a PDF opens
    10. Securing PDFs with Adobe Experience Manager
    11. Protected View feature for PDFs
    12. Overview of security in Acrobat and PDFs
    13. JavaScripts in PDFs as a security risk
    14. Attachments as security risks
    15. Allow or block links in PDFs
  12. Electronic signatures
    1. Sign PDF documents
    2. Capture your signature on mobile and use it everywhere
    3. Send documents for e-signatures
    4. Create a web form
    5. Request e-signatures in bulk
    6. Collect online payments
    7. Brand your account
    8. About certificate signatures
    9. Certificate-based signatures
    10. Validating digital signatures
    11. Adobe Approved Trust List
    12. Manage trusted identities
  13. Printing
    1. Basic PDF printing tasks
    2. Print Booklets and PDF Portfolios
    3. Advanced PDF print settings
    4. Print to PDF
    5. Printing color PDFs (Acrobat Pro)
    6. Printing PDFs in custom sizes
  14. Accessibility, tags, and reflow
    1. Create and verify PDF accessibility
    2. Accessibility features in PDFs
    3. Reading Order tool for PDFs
    4. Reading PDFs with reflow and accessibility features
    5. Edit document structure with the Content and Tags panels
    6. Creating accessible PDFs
    7. Cloud-based auto-tagging
  15. Searching and indexing
    1. Creating PDF indexes
    2. Searching PDFs
  16. Multimedia and 3D models
    1. Add audio, video, and interactive objects to PDFs
    2. Adding 3D models to PDFs (Acrobat Pro)
    3. Displaying 3D models in PDFs
    4. Interacting with 3D models
    5. Measuring 3D objects in PDFs
    6. Setting 3D views in PDFs
    7. Enable 3D content in PDF
    8. Adding multimedia to PDFs
    9. Commenting on 3D designs in PDFs
    10. Playing video, audio, and multimedia formats in PDFs
    11. Add comments to videos
  17. Print production tools (Acrobat Pro)
    1. Print production tools overview
    2. Printer marks and hairlines
    3. Previewing output
    4. Transparency flattening
    5. Color conversion and ink management
    6. Trapping color
  18. Preflight (Acrobat Pro)
    1. PDF/X-, PDF/A-, and PDF/E-compliant files
    2. Preflight profiles
    3. Advanced preflight inspections
    4. Preflight reports
    5. Viewing preflight results, objects, and resources
    6. Output intents in PDFs
    7. Correcting problem areas with the Preflight tool
    8. Automating document analysis with droplets or preflight actions
    9. Analyzing documents with the Preflight tool
    10. Additional checks in the Preflight tool
    11. Preflight libraries
    12. Preflight variables
  19. Color management
    1. Keeping colors consistent
    2. Color settings
    3. Color-managing documents
    4. Working with color profiles
    5. Understanding color management

You sometimes see a warning when you open a PDF. The warning comes in many forms (three are shown below).

Security warnings
Security warnings

What does the warning mean?

The warning is asking whether you trust the people who sent you the PDF or the site in which the PDF is displayed. The warning appears because the PDF content can potentially harm your computer. For example, the warning is displayed for PDFs that can transfer or run programs and macros. It does not necessarily mean that the PDF is harmful.

What is the right action to take?

Some product features assign trust through their own Preferences panel. For example, the Trust Manager includes for managing URL access, and Multimedia Trust (Legacy) has options for playing embedded multimedia. For features affected when enhanced security is enabled, you can selectively allow restricted actions by using a method described in Bypass enhanced security restrictions.

Lưu ý:

To open Preferences, choose Edit > Preferences (Windows) or Acrobat / Adobe Acrobat Reader  > Preferences (Mac OS).

If you know and trust the sender

If you trust the PDF or the company or individual who sent it, click the Options, Allow, or Play button. (The buttons vary depending on the warning.) You can now view the PDF.

If you don’t know or trust the sender

If you don't trust the PDF or don't know who created it or where it came from, don't click the Options, Allow, or Play button. Acrobat and Adobe Acrobat Reader continues to block the suspicious content or actions. To hide the warning, click the Close or Cancel button. If you click any of the blocked content, the warning reappears.

No Options, Allow, or Play button?

If the warning does not contain an Options, Allow, or Play button, your administrator has disabled this feature. You cannot choose to trust or allow this content. Click the Close or Cancel button to hide the warning. You can view the PDF, but you cannot access any of the blocked content. Contact your administrator for more information.

Lưu ý:

For a full list of articles about security, see Overview of security in Acrobat and PDF content.

When are security warnings displayed?

Security warnings can be displayed in the following situations:

Blacklisted JavaScript

JavaScript is a computer language in widespread use. JavaScript code can be vulnerable to attacks, and JavaScript can be used to open websites. Adobe regularly updates the blacklist with known JavaScript vulnerabilities. If a PDF tries to access blacklisted JavaScript, you see a message in the yellow document bar, at the top.

For administrators:

 

Security settings updates

Adobe periodically distributes certificates for security purposes. These downloads help ensure that digitally signed PDFs from trusted sources maintain their trusted status. If you receive an update from an unknown source, verify that it is from a web address that you trust before proceeding. Updates from untrusted websites can create vulnerabilities on your computer.

 

Accessing stream objects (XObjects)

Acrobat and Reader display a warning when a PDF attempts to access external content identified as a stream object. For example, a URL might point to an external image. The silent transmission of data can pose a security risk as Acrobat and Reader communicate with an external source.

 

Inserting data into PDFs and forms

A warning appears when an untrusted source attempts to add data to a PDF form. Although this data-injection feature can streamline workflows in your organization, it can also be used to add malicious data into a PDF.

 

Silent printing

Silent printing is printing to a file or printer without your confirmation. It is a potential security risk because a malicious file can silently print multiple times to your printer, wasting printer resources. It can also prevent other documents from printing by keeping the printer busy.

Contact your system administrator to determine when to allow silent printing.

 

Web links

In addition to visible web links in a PDF document, form fields can contain hidden JavaScript that open a page in a browser or silently request data from the Internet.

Lưu ý:

Acrobat and Reader X, 9.3, and 8.2 enable enhanced security by default. Adobe recommends that you enable enhanced security if it is not already enabled, and bypass restrictions only for trusted content.

 Adobe

Nhận trợ giúp nhanh chóng và dễ dàng hơn

Bạn là người dùng mới?

Adobe MAX 2024

Adobe MAX
Hội thảo sáng tạo

14–16/10 Bãi biển Miami và trực tuyến

Adobe MAX

Hội thảo sáng tạo

14–16/10 Bãi biển Miami và trực tuyến

Adobe MAX 2024

Adobe MAX
Hội thảo sáng tạo

14–16/10 Bãi biển Miami và trực tuyến

Adobe MAX

Hội thảo sáng tạo

14–16/10 Bãi biển Miami và trực tuyến