PDF malware analysis — malicious · 8c966250202f4649

MALICIOUS

PDF

21.6 KB

MD5: ecddafa699814679552d2bf95fc087e5 SHA-1: c62ae62dce4659a8c969594fe051772cd7c1ee1c SHA-256: 8c966250202f464973929a31886b6ba8d4454425f9348000833091f9d9e8c59a

130 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1059.001 PowerShell

The PDF sample contains XFA JavaScript that utilizes a heap spray technique, indicating an attempt to exploit a vulnerability. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript, identified as stream_000_off00000047.js, is likely responsible for executing the exploit and delivering a secondary payload, though its exact function is obscured by obfuscation.

Machine Learning

Nyx PDF Classifier malicious score 0.9964

Heuristics 5

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.
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)
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_off00000047.js` `28e91a6e639dbc4af1d70dea66e612303292232dacc7cfcad37a14d33e928ccb`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x47	4194304 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 18 long base64-like blob(s).

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