Malicious PDF — malware analysis report

Static analysis result for SHA-256 d9b273e145e22401…

MALICIOUS

PDF

5.3 KB
MD5: 17f9b59e37ef9ed8dd1f3580e2210cdb SHA-1: 0adc43631518b4960790cb4e95f7430c17d590e1 SHA-256: d9b273e145e224011148f222767931a85d4dcd030b6826b6b20078f346cf61fc
144 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 JavaScript/JScript T1566.002 Spearphishing Attachment

This PDF file was flagged as malicious by ML classifiers and ClamAV, indicating it contains an exploit. The presence of PDF_JAVASCRIPT, PDF_JS, and PDF_FROMCHARCODE heuristics, along with the use of ASCIIHexDecode and ASCII85Decode filters, strongly suggests the execution of embedded JavaScript. This script is likely responsible for delivering a second-stage payload, as indicated by the ClamAV detection name 'Pdf.Exploit.Agent-36178'.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 7

  • 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
  • PDF differential parser failed info PDF_DIFFERENTIAL_PARSE_FAILED
    The cross-check parser (pdfminer.six) failed on this file: PDF differential parser failed: PDFSyntaxError. Static heuristics still ran and any of their findings above are valid; only the differential cross-check signal is missing.

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