PDF malware analysis — malicious · 81dda8cd3d655c6e

MALICIOUS

PDF

69.1 KB

MD5: 9ee29ecb0ec5be89641ee05f6612c147 SHA-1: 0a50859373745b7c451f7c9efd88df55b2eccf73 SHA-256: 81dda8cd3d655c6e932283a7404b1dbb85f9a4324d35e6c8e7bd7714012591d3

168 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

This PDF file contains XFA (XML Forms Architecture) which is known to be a vector for exploits. Heuristics indicate the presence of XFA heap spray exploit code and risky executable script within a decoded stream. The ML classifier strongly flagged this PDF as malicious. The extracted JavaScript, stream_000_off0000003d.js, is highly suspicious and likely responsible for the malicious behavior, potentially downloading and executing a second-stage payload.

Machine Learning

Nyx PDF Classifier malicious score 0.9194

Heuristics 6

XFA form contains risky executable script high CVE related PDF_XFA_SCRIPT

PDF embeds an XFA form whose script block contains exploit, submission/launch, or shell-execution primitives. Ordinary LiveCycle print/update scripts are left as generic XFA/JS signals unless stronger behavior is present.
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_off0000003d.js` `19d28eef426afeee002b47cc4849d9010ca29ebd5c5eeb89e384934ab43c1b97`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x3D	4194304 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).

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