Malicious PDF — malware analysis report

Static analysis result for SHA-256 13a4bd3c9b297bba…

MALICIOUS

PDF

9.3 KB
MD5: 59a7cdca5f024891daaae4839ce94b55 SHA-1: 469a845097e364ff1c10cae6f811f809509b78e3 SHA-256: 13a4bd3c9b297bbac656810afe10abd9d29fbfde10175dc2010299fc3687b157
146 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

This PDF document utilizes an XFA form with embedded JavaScript. The JavaScript function 'hx' decodes a hex-encoded string from the 'subject' property and then evaluates it, indicating a likely attempt to download and execute a secondary payload. The ML classifier strongly flags this PDF as malicious.

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.
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • 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. (matched inside decoded stream)
  • Embedded script payload in PDF stream low 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.
  • 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/xci/1.0/
    • http://www.xfa.org/schema/xfa-template/2.4/
    • http://www.xfa.org/schema/xfa-data/1.0/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_file_obj0041.bin
0f1d158a09dfa2e842c89e232602d2410ecf5f79fdcf30e55881a654e200d104
pdf-embedded-file PDF EmbeddedFile object 41 at offset 0x52 1165 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
deobfuscated.js
c1565679613a88242dde87c14d1ece0bd8dc197e3e9b9016b4b8874abbbc5132
deobfuscated-js PDF JavaScript deobfuscation pass 2015 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).