PDF-based malware:

 

PDF-based malware is a significant cybersecurity threat due to the widespread use and flexibility of the PDF format. Here are some common techniques used in PDF-based malware:

## JavaScript Execution

PDFs can contain embedded JavaScript code that executes when the file is opened. Malicious actors exploit this feature to:

- Download and execute additional payloads

- Exploit vulnerabilities in PDF readers

- Steal sensitive information from the system

JavaScript in PDFs can be obfuscated to evade detection[1].

## Embedded Objects

Attackers can hide malicious objects within the PDF structure:

- Executable files

- Malicious scripts

- Other harmful content

These objects may be compressed or encoded to avoid detection by security software[2].

## Exploitation of Vulnerabilities 

Some attacks target vulnerabilities in PDF reader software:

- Buffer overflows

- Use-after-free bugs

- Other memory corruption issues

Successful exploitation can lead to arbitrary code execution on the victim's system[3].

## Phishing and Social Engineering

PDFs are often used in phishing campaigns:

- Malicious links disguised as legitimate content

- Fake forms to capture credentials

- Convincing documents that lure users into taking harmful actions

## Stream Manipulation

PDF streams can contain compressed and encoded data, allowing attackers to:

- Hide malicious code

- Evade signature-based detection

- Deliver payloads in seemingly innocuous files[3]

## Protection Measures

To defend against PDF-based malware:

- Keep PDF readers and systems updated

- Use security software with PDF scanning capabilities

- Be cautious when opening PDFs from unknown sources

- Disable JavaScript in PDF readers when possible

- Use sandboxed environments to open suspicious files[4]

By understanding these techniques, security professionals can better detect and mitigate threats posed by malicious PDF files.

Citations:

[1] https://github.com/filipi86/MalwareAnalysis-in-PDF

[2] https://www.adobe.com/acrobat/resources/can-pdfs-contain-viruses.html

[3] https://intezer.com/blog/incident-response/analyze-malicious-pdf-files/

[4] https://www.reddit.com/r/hacking/comments/108sp8f/how_to_know_if_a_pdf_contains_malware/

[5] https://www.sentinelone.com/blog/malicious-pdfs-revealing-techniques-behind-attacks/

[6] https://threatresearch.ext.hp.com/pdf-malware-is-not-yet-dead/