Malicious PDF — malware analysis report

Static analysis result for SHA-256 4b3e52d8d71abbb1…

MALICIOUS

PDF

3.8 KB
MD5: ad1f3ab7292162df70fd4dc60f634b59 SHA-1: 17e38eeba2d20a9c285937f6d0edeb15712a39a9 SHA-256: 4b3e52d8d71abbb1a7100b5e11edb9e62af36e0c16445b6ad8bf02b7d32d5f08
142 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1566.002 Spearphishing Attachment

The file is a PDF that has been flagged by multiple heuristics and a machine learning classifier as malicious. ClamAV also detected it as Pdf.Exploit.Agent-36178. The presence of PDF_JAVASCRIPT, PDF_JS, PDF_FROMCHARCODE, PDF_FILTER_HEX, and PDF_FILTER_85 rules indicates that the PDF contains embedded JavaScript, likely obfuscated, which is used to exploit a vulnerability within the PDF reader. The ML classifier's high confidence score further supports this assessment.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 6

  • ClamAV: Pdf.Exploit.Agent-36178 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36178
  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
  • 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)
  • ASCII85Decode filter (with exploit indicators) low PDF_FILTER_85
    ASCII85 encoding filter present alongside exploit delivery indicators — uncommon outside of obfuscation