Malicious PDF — malware analysis report

Static analysis result for SHA-256 fce791f1fcef49c5…

MALICIOUS

PDF

25.9 KB
MD5: f4f5c23cba15bf0e3271af18d550b546 SHA-1: ff7922184d8ab25fd0ec8c883c6333fcb04b68c2 SHA-256: fce791f1fcef49c5e8c802c37071c33d5c59f43b1ac257a017015cdbfe4ac0e2
156 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

This PDF document contains an XFA form with embedded, obfuscated JavaScript. The script utilizes functions like unescape() and String.fromCharCode(), indicating an attempt to hide malicious code. The ML classifier strongly flags this PDF as malicious. The primary attack vector appears to be the execution of this embedded script, which likely leads to the exploitation of a PDF viewer vulnerability and the subsequent download or execution of a secondary payload, as suggested by the embedded file artifact.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 8

  • 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.
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits
  • 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.
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
  • 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.
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://ns.adobe.com/xdp/
    • http://www.xfa.org/schema/xfa-template/2.5/
    • http://www.xfa.org/schema/xfa-data/1.0/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_file_obj0008.bin
c3a36e6d41a66c12b8c9c5d18ccab5c94026c9adab1b65d153829157b0fd215b		 pdf-embedded-file PDF EmbeddedFile object 8 at offset 0xC6 25800 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).

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