Master malicious document analysis. This scenario challenges you to identify the correct tools and methodology for safely examining the internal structure and hidden payloads of suspicious PDF files.
An employee in the Finance department reported a suspicious email containing an attachment named Invoice_Q3_Overdue.pdf. Shortly after opening the file, the employee's workstation exhibited unusual network activity communicating with an unknown external IP address.
You have acquired the suspect workstation's memory and isolated the malicious PDF attachment into a secure forensic sandbox. During the Examination phase, you need to dissect the document to determine how the payload was executed.
Initial string extraction reveals the presence of obfuscated data streams and suspicious tags, indicating potential embedded scripting.
To determine if a PDF file contains malicious Javascript code, which of the following tools is most suitable for analyzing the PDF's object structure?
The strings analysis confirms the PDF structure includes an /OpenAction directive, meaning an action will execute automatically when the document is opened. This action points to a /JavaScript payload stored inside a compressed data stream (/FlateDecode).
Examination & Analysis (Static Malware Analysis). The investigator is conducting static analysis on the malicious artifact to understand its capabilities without executing the payload in a live environment.
A. PDFStreamDumper or peepdf. Both of these are purpose-built digital forensics and malware analysis tools. They parse the PDF file format into its hierarchical object structure, allow investigators to easily locate suspicious keywords (like /JS, /Launch), and can safely decompress (deflate) the embedded streams for further code analysis.
/FlateDecode stream) containing the actual malicious JavaScript.An investigator will load the suspicious document into peepdf using an isolated Linux forensic workstation (like REMnux). They will use the command extract js > payload.txt to safely dump the obfuscated JavaScript. Following this, tools like SpiderMonkey or JS beautifiers are used to deobfuscate the script and identify the attacker's Command & Control (C2) domains.
PDFs are not just flat text documents; they are complex structures containing trees of objects, dictionaries, and executable elements. Key indicators of compromise in PDF forensics include:
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