PDF malware analysis — malicious · f7d91a6c27669fcb

MALICIOUS

PDF

33.4 KB

MD5: f8ebe0486c57285a949a4fb1dc363636 SHA-1: 103718dc8b9ee1d2a62fcb9310652e63e273166e SHA-256: f7d91a6c27669fcba3830027341f151a0534f04acc1ef483776b914dd44fba60

190 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious File: User Execution: Malicious File

The PDF file contains XFA JavaScript that triggers a heap spray exploit, a critical finding. This script is designed to download and execute a second-stage payload, as indicated by the 'PDF_EMBEDDED_SCRIPT_PAYLOAD' heuristic. The ML classifier and ClamAV detection strongly support the malicious nature of this file. The embedded JavaScript file, stream_000_off00000063.js, is the primary indicator of compromise.

Machine Learning

Nyx PDF Classifier malicious score 0.9922

Heuristics 7

XFA JavaScript heap-spray exploit code critical PDF_XFA_HEAP_SPRAY

PDF contains XFA script content with heap-spray or shellcode-like JavaScript markers such as large encoded word sequences, util.pack, large arrays, or spray variable names. This is a weaponised Adobe Reader exploit pattern, not a normal interactive form.
ClamAV: Heuristics.PDF.ObfuscatedNameObject critical CLAMAV_DETECTION

ClamAV detected this file as malware: Heuristics.PDF.ObfuscatedNameObject
Embedded script payload in PDF stream medium PDF_EMBEDDED_SCRIPT_PAYLOAD

PDF stream bytes contain an HTML/XFA <script> tag without accompanying Windows shell-execution primitives — common in accessible XFA forms but worth surfacing for analyst review.
XFA form low PDF_XFA

PDF uses XML Forms Architecture — can contain script logic
String.fromCharCode low PDF_FROMCHARCODE

String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
PDF differential parser failed info PDF_DIFFERENTIAL_PARSE_FAILED

The cross-check parser (pdfminer.six) failed on this file: PDF differential parser failed: PSSyntaxError. Static heuristics still ran and any of their findings above are valid; only the differential cross-check signal is missing.
Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`stream_000_off00000063.js` `7160f29fb3fa274800a4668f1f25248abb3475382431bac840494dc4d1734aab`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x63	84692 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).

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