Malicious PDF — malware analysis report

Static analysis result for SHA-256 b135c785cd045823…

MALICIOUS

PDF

6.7 KB Created: 2009-11-17 23:22:12 Authoring application: Scribus 1.3.5svn (via Scribus PDF Library 1.3.5svn)
MD5: dd708069812740a77b63e81bc579b0a4 SHA-1: b9adceb012b91cec351184db4599e7e74570876e SHA-256: b135c785cd04582314918a96f6176819481115a49a9e438999d58dfaef283708
96 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The ML classifier strongly flags this PDF as malicious. The JavaScript stream, decoded using unescape() and String.fromCharCode, likely contains obfuscated code intended to download and execute a second-stage payload. The presence of the 'javascript_obj0016_001.js' artifact further supports this. The exact nature of the payload could not be determined due to obfuscation.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 5

  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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.

FilenameKindSourceSize
javascript_obj0016_001.js
b52aaeb5c44d055c58ee21d35f81ed89601b7b6f7284ff1451eb52c541ba45b5
pdf-javascript-stream PDF /JS object 16 at offset 0xC9A 12549 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s).