Malicious PDF — malware analysis report

Static analysis result for SHA-256 0f7ae81cd21a025f…

MALICIOUS

PDF

9.5 KB
MD5: 5281f99b1f83885c88fa8d0cdb3a5794 SHA-1: d0b5fa2c9b6b7b7110a7c0aecad7c3f88e1a0d4f SHA-256: 0f7ae81cd21a025fb79fbd5c7d666b8e1049ebd1e1de10a235b3f0c4ea047343
146 Risk Score

Malware Insights

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

This PDF file utilizes XFA forms and embedded JavaScript to achieve malicious execution. The JavaScript function `hx` decodes a hex-encoded string from the `subject` property, which is then executed via `eval()`. This mechanism is designed to download and execute a second-stage payload, as indicated by the embedded file and deobfuscated JavaScript artifact. 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
d3cb4624d0ae9e6ad17d2f2844a322f7e5b0aca858c2239b15af92fe2e88818c
pdf-embedded-file PDF EmbeddedFile object 41 at offset 0x52 1161 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
deobfuscated.js
89f537b95d99d50bce8e49d2dfb63930048f23218b779dfa2f86e01a072e4aa5
deobfuscated-js PDF JavaScript deobfuscation pass 2108 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).