What is PDF file ?

• PDF (Portable Document Format) is a file format that captures all of the components of a printed document as an electronic image that can be viewed, navigated, printed, or forwarded to others. PDF files are very suitable for publications that require the original graphic appearance to be preserved online, such as magazine articles, product brochures.
• in more simple way, a PDF (Portable Document Format) is a widely used file format designed to preserve the exact appearance of a document, including its text, images, fonts, graphics, and layout. Unlike editable formats such as Word documents, a PDF ensures that the content looks the same on any device, operating system, or software used to open it. This makes PDFs ideal for sharing, printing, archiving, and distributing professional documents such as reports, manuals, contracts, brochures, flyers, and magazine articles. Users can view, navigate, search, print, and securely share PDF files while maintaining the document’s original formatting and visual design.

Can PDF be malicious ?

• Viruses and dangerous executable code can be carried in Adobe PDF documents. Multimedia material, hyperlinks, JavaScript code, clickable action, and system commands are all common places for malware to hide. When consumers open the file or interact with the embedded material once it has been opened, the malware assault is launched.

• a PDF file can contain malicious code, but not in the same way as a normal executable file (.exe).

A PDF can embed active content such as:

• JavaScript code
• Embedded files (e.g., executables, Office documents)
• Links to malicious websites
• Launch actions that attempt to run programs
• Multimedia objects that exploit vulnerabilities in PDF readers

The attack usually works in one of two ways:

1. Social Engineering
   • The PDF tricks the user into clicking a link, opening an attachment, or allowing an action.
   • Example: "Click here to view the invoice."
2. Software Exploitation
   • The PDF contains specially crafted content that exploits a vulnerability in the PDF reader (such as Adobe Reader).
   • Simply opening the PDF may trigger the exploit if the software is unpatched.

Example

An attacker sends a PDF named:

Invoice_2026.pdf