Malicious PDF — malware analysis report

Static analysis result for SHA-256 78dce3acb5f98d34…

MALICIOUS

PDF

24.5 KB
MD5: a7386b9adac8518d71cbcb95ba7ea3ce SHA-1: ef9d1dabf2b882047d9b18d25ce28a939f2f7726 SHA-256: 78dce3acb5f98d34eae33c8639d8c8581b3004a4c33561b53add519e9fd9e6ea
146 Risk Score

Malware Insights

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

This PDF document contains XFA forms and embedded JavaScript, indicated by multiple high-severity heuristics including PDF_XFA_SCRIPT and PDF_UNESCAPE. The embedded script, which uses functions like unescape() and String.fromCharCode(), is designed to download and execute a secondary payload from the embedded artifact 'embedded_file_obj0008.bin'. The ML classifier strongly flags this as malicious, suggesting exploitation for client execution.

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 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.
  • 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/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
0fc685f51dd72579e52e93c2092d7e72dfac557df0d294efd4b3defb38c13315		 pdf-embedded-file PDF EmbeddedFile object 8 at offset 0xC6 24388 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).

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